Energy Tech Laboratories DHG240 User Manual

INSTALLATION

INSTRUCTION

SUNLINE GAS/ELECTRIC

SINGLE PACKAGE

AIR CONDITIONERS

CONTENTS

GENERAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

SAFETY CONSIDERATIONS . . . . . . . . . . . . . . . . . . 3

AGENCY APPROVALS . . . . . . . . . . . . . . . . . . . . . . 4

INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

MAINTENANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

COMPLETE TABLE OF CONTENTS ON FOLLOWING PAGE

MODELS: DHG180 (15 TON, 10.0 EER)

DHG240 (20 TON, 9.7 EER)

208/230/460 VOLT

208/230/575 VOLT

MODELS ONLY

SAVE THIS MANUAL

035-17233-000-C-0702

D 1 HG 180 E 180 25 EC

TABLE 1: PRODUCT NOMENCLATURE

Model Number

Description

Model #

Options

Product Category

Product Generation

Product Identifier

D = Air Cond., Single Package

1 = 1st Generation

HG = Gas/Electric

180

Nominal Cooling Capacity

180 = 15 Tons

240 = 20 Tons

A = No Heat

E = Electric Heat

Factory Installed Heat

Nominal Heating Capacity

Voltage Code

N = Natural Gas

018 = 18 kW

036 = 36 kW

054 = 54 kW

072 = 72 kW

018

25 = 208/230-3-60

58 = 575-3-60

46 = 460-3-60

EC = Single Input Economizer

DK = Dual Input Economizer

FD = Sing. Input Economizer w/ Power CF = Dual Input Economizer with Power

Factory Installed

Option Code

Exhaust

BG = Motorized Outdoor Air Damper

GENERAL

SAFETY CONSIDERATIONS

YORK Model DHG units are single package high efficiency

gas-fired central heating furnaces with cooling unit designed

for outdoor installation on a rooftop or a slab.

Installer should pay particular attention to the words: NOTE,

CAUTION, and WARNING. Notes are intended to clarify or

make the installation easier. Cautions are given to prevent

equipment damage. Warnings are given to alert installer that

personal injury and/or equipment damage may result if instal-

lation procedure is not handled properly.

The units are completely assembled on rigid, permanently

attached base rails. All piping, refrigerant charge, and electri-

cal wiring is factory installed and tested. The units require

electric power, gas connection, duct connections, installation

of combustion air inlet hood, flue gas outlet hoods and fixed

outdoor air intake damper (units without economizer or

motorized damper option only) at the point of installation.

Due to system pressure, moving parts and electrical compo-

nents, installation and servicing of air conditioning equipment

can be hazardous. Only qualified, trained, service personnel

should install, repair, maintain or service this equipment.

The gas-fired heaters have aluminized-steel tubular heat

exchangers and spark ignition with proven pilot.

Observe all precautions in the literature, on labels and tags

accompanying the equipment whenever working on air condi-

tioning equipment. Be sure to follow all other safety precau-

tions that apply.

Wear safety glasses and work gloves, and follow all safety

codes. Use a quenching cloth and have a fire extinguisher

available for all brazing operations.

FOR YOUR SAFETY IF YOU SMELL GAS:

a. Open windows.

b. Don’t touch electrical switches; do not use any

phones in the area of the gas leak.

c. Extinguish any open flame.

This product must be installed in strict compliance

with the enclosed installation instructions and any

applicable local, state, and national codes includ-

ing, but not limited to, building, electrical and

mechanical codes.

d. Immediately call your gas supplier from another

location. Follow your gas supplier’s instructions.

e. If you cannot reach your gas supplier, call the fire

departments.

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INSTALLATION

LIMITATIONS

Improper installation may create a condition where

the operation of the product could cause personal

injury or property damage.

These units must be installed in accordance with the follow-

ing national and local safety codes:

1. National Electrical Code ANSI/NFPA No. 70.

2. National Fuel Gas Code Z223.1.

REFERENCE

3. Gas-Fired Central Furnace Standard ANSI Z21.47a.

4. Local gas utility requirements.

Additional information on the design, installation, operation

and service of this equipment is available in the following ref-

erence forms:

Refer to Table 2 for Unit Application Data and to Table 4 for

Gas Heat Application Data.

•

44-320-10 - Barometric Relief Damper Accessory

530.18-N6.1V - Propane Conversion Accessory (USA)

530.18-N6.2V - High Altitude Accessory (Nat. Gas)

530.18-N6.3V - High Altitude Accessory (Propane)

TABLE 2: UNIT APPLICATION DATA

MODEL SIZE

208/230-3-60

15 TON

20 TON

RENEWAL PARTS:

187/253

Refer to the Renewal Parts Manual for complete listing of

replacement parts on this equipment.

Voltage Variation,

460-3-60

575-3-60

414/506

518/630

Min./Max

All forms referenced in this instruction may be ordered from:

Supply Air CFM, Min./Max.

4500/7200

6000/9400

Wet Bulb Temperature (°F) of air

on Outdoor Coil Min./Max.

57/72

Standard Register

2101 West Tecumseh Road

Norman, Oklahoma 73069

Toll Free Phone (877) 318-9675

Toll Free Fax: (877) 379-7920

Dry Bulb Temperature (°F) of air

25/120

on Outdoor Coil Min./Max.

Rated in accordance with ARI Standard 110, utilization

range “A”.

AGENCY APPROVALS

A low ambient accessory is available for operation

down to 0°F.

Design certified by ETL as follows:

After installation, the unit must be adjusted to obtain a tem-

perature rise within the range specified on the unit rating

plate.

1. For use as a forced air furnace with cooling unit.

2. For outdoor installation only.

3. For installation on combustible material.

4. For use with natural gas or propane gas.

If components are to be added to a unit to meet local codes,

they are to be installed at the dealer's and/or the customer's

expense.

INSPECTION

Size of unit for proposed installation should be based on heat

loss/heat gain calculation made according to the methods of

the Air Conditioning Contractors of America (ACCA).

As soon as a unit is received, it should be inspected for possi-

ble damage during transit. If damage is evident, the extent of

the damage should be noted on the carrier's freight bill. A

separate request for inspection by the carrier's agent should

be made in writing. Refer to Form 50.15-NM for additional

information.

This furnace is not to be used for temporary heating of build-

ings or structures under construction.

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LOCATION

Use the following guidelines to select a suitable location for

these units.

Length of the forks must be a minimum of 90”.

1. Unit is designed for outdoor installation only.

2. Condenser coils must have an unlimited supply of air.

Where a choice of location is possible, position the unit

on either north or east side of building.

An adhesive backed label is provided over the out-

side of the combustion air inlet opening to prevent

moisture from entering the unit which could cause

damage to electrical components. Allow this clo-

sure label to remain in place until the combustion

air hood is to be installed (refer to Figure 7).

Excessive exposure of this furnace to contami-

nated combustion air may result equipment dam-

age or personal injury. Typical contaminates

include: permanent wave solutions, chlorinated

waxes and cleaners, chlorine based swimming

pool chemicals, water softening chemicals, carbon

tetrachloride, Halogen type refrigerants, cleaning

solvents (e.g. perchloroethylene), printing inks,

paint removers, varnishes, hydrochloric acid,

cements and glues, antistatic fabric softeners for

clothes dryers, masonry acid washing materials.

3. For ground level installation, use a level concrete slab

with a minimum thickness of 4 inches. The length and

width should be at least 6 inches greater than the unit

base rails. Do not tie slab to the building foundation.

4. Roof structures must be able to support the weight of the

unit and its options and/or accessories. Unit must be

installed on a solid level roof curb or appropriate angle

iron frame.

FIGURE 1: TYPICAL RIGGING

Refer to Table 6 for unit weights and to Figure 2 for approxi-

mate center of gravity.

If a unit is to be installed on a roof curb or special

frame other than a YORK roof curb, gasketing

must be applied to all surfaces that come in con-

tact with the unit underside.

5. Maintain level tolerance to 1/2" maximum across the

entire length or width of the unit.

RIGGING AND HANDLING

Exercise care when moving the unit. Do not remove any

packaging until the unit is near the place of installation. Rig

the unit by attaching chain or cable slings to the round lifting

holes provided in the base rails. Spreaders, whose length

exceeds the largest dimension across the unit, MUST be

used across the top of the unit. Refer to Figure 1.

FIGURE 2 : CENTER OF GRAVITY

CLEARANCES

Units may also be moved or lifted with a forklift, from the front

or rear only, providing that an accessory skid is used.

All units require certain clearances for proper operation and

service. Installer must make provisions for adequate

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combustion and ventilation air in accordance with Section

5.3, Air for Combustion and Ventilation of the National Fuel

Gas Code, ANSI Z223.1 (in U.S.A.) or Sections 7.2, 7.3 or

7.4 of Gas Installation Codes CAN/CGA-B149.1 and .2 (in

Canada) and/or applicable provisions of the local building

codes. Refer to Table 8 for the clearances required for

combustible construction, servicing, and proper unit

operation.

Do not permit overhanging structures or shrubs to

obstruct outdoor air discharge outlet, combustion

air inlet or vent outlets.

FIGURE 3 : FIXED OUTDOOR AIR DAMPER

DUCTWORK

Gasketing and mounting screws are provided in a parts bag

attached to the hood assembly. Apply gasketing to the three

flange surfaces on the hood prior to installing the hood.

Extend gasketing 1/4" beyond the top and bottom of the two

side flanges to insure adequate sealing.

Ductwork should be designed and sized according to the

methods in Manual Q of the Air Conditioning Contractors of

America (ACCA).

A closed return duct system shall be used. This shall not pre-

clude use of economizers or outdoor fresh air intake. The

supply and return air duct connections at the unit should be

made with flexible joints to minimize noise.

Adjusting the damper to the desired air flow may be done

before mounting the hood into position or (after installation)

by removing the front hood panel or the screen on the bottom

of the hood. Damper baffle in position 1 will allow approxi-

mately 10% recirculated air flow, position 2 approximately

15% and, to allow approximately 25%, remove the damper

baffle.

The supply and return air duct systems should be designed

for the CFM and static requirements of the job. They should

NOT be sized to match the dimensions of the duct connec-

tions on the unit.

On units with bottom return air applications, install the

damper assembly over the opening in the side return air

access panel. Remove and discard the opening cover and

the covering over the hood mounting holes (used for ship-

ping) before installing. Secure with the screws provided.

When fastening ductwork to side duct flanges on

unit, insert screws through duct flanges only. DO

NOT insert screws through casing.

On units with side return air applications, install the damper

assembly on the return air ductwork as close to the unit as

possible. Cut an opening 16" high by 18" wide in the ductwork

to accommodate the damper. Using the holes in the hood

flanges as a template, drill 9/64" dia. (#26 drill) holes into the

Outdoor ductwork must be insulated and water-

proofed.

ductwork and secure with the screws provided.

Refer to Figure 10 and 12 for information concerning side and

bottom supply and return air duct openings.

FIXED OUTDOOR AIR INTAKE DAMPER

This damper is shipped inside the return air compartment. It

is completely assembled and ready for installation. A damper

baffle inside of the hood is adjustable to provide variable

amounts of outdoor air intake on units that are not provided

with an economizer or a motorized damper option. Refer to

Figure 3.

If outdoor air intake will not be required on units

with bottom return air applications, the damper

assembly should still be mounted on the side

return air access panel, per the instructions above,

to insure moisture is not drawn into the unit during

operation. The covering over the mounting holes

only need be removed. Do not remove the opening

cover.

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•

Side Supply & Return Air compartments (Two panels)

Blower compartment (Three panels)

Main control box

Filter compartment

Outdoor Air compartment (Two panels)

CONDENSATE DRAIN

Plumbing must conform to local codes. Use a sealing com-

pound on male pipe threads. Install a condensate drain line

from the 1" NPT female connection on the unit to an open

drain.

Refer to Figure 10 for location of these access panels.

Make sure that all screws and panel latches are

replaced and properly positioned on the unit to

maintain an air-tight seal.

THERMOSTAT

The room thermostat should be located on an inside wall

approximately 56" above the floor where it will not be subject

to drafts, sun exposure or heat from electrical fixtures or

appliances. Follow manufacturer's instructions enclosed with

thermostat for general installation procedure. Seven color

coded insulated wires (#18 AWG) should be used to connect

thermostat to unit.

FIGURE 4 : RECOMMENDED DRAIN PIPING

An alternate drain connection (1" NPT female coupling) is

provided inboard on the same centerline as the exterior loca-

tion.

NOTE: The condensate drain line MUST be trapped to pro-

vide proper drainage. See Figure 4.

POWER AND CONTROL WIRING

COMPRESSORS

Field wiring to the unit must conform to provisions of the

National Electrical Code, ANSI / NFPA No. 70 (latest edition)

and/or local ordinances. The unit must be electrically

grounded in accordance with N.E.C. and/or local codes. Volt-

age tolerances which must be maintained at the compressor

terminals during starting and running conditions are indicated

on the unit Rating Plate and Table 2.

Units are shipped with compressor mountings factory-

adjusted and ready for operation.

The internal wiring harness furnished with this unit is an inte-

gral part of a ETL design certified unit. Field alteration to com-

ply with electrical codes should not be required.

Do Not loosen compressor mounting bolts.

FILTERS

A fused disconnect switch should be field provided for the

unit. The switch must be separate from all other circuits. Wire

entry at knockout openings require conduit fittings to comply

with NEC and/or local codes. Refer to Figure 10 for installa-

tion location. If any of the wire supplied with the unit must be

replaced, replacement wire must be of the type shown on the

wiring diagram and the same minimum gauge as the

replaced wire.

Two-inch filters are supplied with each unit. Filters must

always be installed ahead of the evaporator coil and must be

kept clean or replaced with same size and type. Dirty filters

will reduce the capacity of the unit and will result in frosted

coils or safety shutdown. Minimum filter area and required

sizes are shown in Table 6.

SERVICE ACCESS

Electrical line must be sized properly to carry the load. Each

unit must be wired with a separate branch circuit fed directly

Access to all serviceable components are provided by the fol-

lowing removable panels:

from the meter panel and properly fused.

Refer to Figure 5 for typical field wiring and to the appropriate

unit wiring diagram for control circuit and power wiring infor-

mation.

•

Compressor compartment

Gas Heat compartment (Two panels)

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Typical supply piping arrangements are shown in Figures 6

and 7. All shaded items are field-supplied.

Two grommets are shipped in the blower compartment (in

parts bag taped to the blower housing) of every unit with gas

heat and should be used in the knockouts when the gas pip-

ing penetrates the front of the unit.

When connecting electrical power and control wir-

ing to the unit, waterproof type connectors MUST

BE USED so that water or moisture cannot be

drawn into the unit during normal operation. The

above waterproofing conditions will also apply

when installing a field-supplied disconnect switch.

After the gas supply piping has been installed, the bottom

opening in the unit should be sealed to prevent water from

leaking into the building.

COMBUSTION DISCHARGE

Gas piping recommendations:

The products of combustion are discharged horizontally

through two screened (hooded) openings on the upper gas

1. A drip leg and a ground joint union must be installed in

the gas piping.

heat access panel.

2. When required by local codes, a manual shut-off valve

may have to be installed outside of the unit.

TABLE 3: CONTROL WIRE SIZES¹

Wire Size

3. Use wrought iron or steel pipe for all gas lines. Pipe dope

should be applied sparingly to male threads only.

120

150

190

305

4. All piping should be cleaned of dirt and scale by ham-

mering on the outside of the pipe and blowing out the

loose dirt and scale. Before initial start-up, be sure that

all of the gas lines external to the unit have been purged

of air.

Max. Wire Length Feet

Total wire length is from unit to room thermostat, and

back to unit.

Solid, Class II copper wire.

Total Wire length is from unit to room thermostat, and

back to unit.

5. The gas supply should be a separate line and installed in

accordance with all safety codes as prescribed under

Limitations. After the gas connections have been com-

pleted, open the main shut-off valve admitting normal

gas pressure to the mains. Check all joints for leaks with

soap solution or other material suitable for the purpose.

NEVER USE A FLAME.

GAS PIPING

Proper sizing of gas piping depends on the cubic feet per

hour of gas flow required, specific gravity of the gas and the

length of run. National Fuel Gas Code Z223.1 should be fol-

lowed in all cases unless superseded by local codes or gas

utility requirements. Refer to Table 5.

6. The furnace and its individual manual shut-off valve must

be disconnected from the gas supply piping system dur-

ing any pressure testing of that system at test pressures

in excess of 1/2 psig (3.48kPa).

The heating value of the gas may differ with locality. The

value should be checked with the local gas utility.

The furnace must be isolated from the gas supply piping

system by closing its individual manual shut-off valve

during any pressure testing of the gas supply piping sys-

tem at test pressures equal to or less than 1/2 psig

(3.48kPa).

NOTE: There may be a local gas utility requirement specify-

ing a minimum diameter for gas piping. All units require a 1

inch pipe connection at the entrance fitting.

GAS CONNECTION

7. A 1/8 inch NPT plugged tapping, accessible for test gage

connection, must be installed immediately upstream of

the gas supply connection to the furnace.

The gas supply line can be routed through the knockouts

located on the front of the unit or through the opening pro-

vided in the unit's base. Refer to Figure 10 to locate these

access openings.

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(

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(

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FIGURE 5 : TYPICAL FIELD WIRING

TABLE 4: GAS HEAT APPLICATION DATA¹

Input Capacity (Mbh)

Output Capacity (Mbh)

Temp Rise °F

0 to 2000 Feet

2,000 to 4,500 Feet

Above Sea Level

2,000 to 4,500 Feet

Above Sea Level

Available on

Models

Gas Rate

At Full Input

Above Sea Level

(Ft. /Hr.)

Min.

300

400

Max.

150

Min.

270

360

Max.

135

Min.

240

320

Max.

213

Min.

Max.

15 & 20 Ton

279

372

200

180

281

Heaters are shipped available fro natural gas, but can be converted to L.P./Propane with Kit Model No. 1NP0418.

Based on maximum input and 1075/Btu/Ft.

The air flow must be adjusted to obtain a temperature rise within the range shown.

MBH rating should be reduced at the rate of 4 percent for each 1,000 feet above 4,500 feet.

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TABLE 5: PIPE SIZING¹

Nominal Iron Pipe Size

Length in Feet

1 in.

1-1/4 in.

1,050

730

100

520

350

285

245

215

195

180

170

160

150

590

500

440

400

370

350

320

305

FIGURE 7 : BOTTOM SUPPLY CONNECTION

Maximum capacity of pipe in cubic feet of gas per hour.

(Based upon a pressure drop of 0.3 inch water column

and 0.6 specific gravity gas.)

EXTERNAL SHUT-OFF

L.P. UNITS, TANKS AND PIPING

All gas heat units are shipped from the factory equipped for

natural gas use only. The unit may be converted in the field

for use with L.P./propane gas with accessory kit model num-

ber 1NP0437.

All L.P./propane gas equipment must conform to the safety

standards of the National Fire Protection Association.

For satisfactory operation, L.P./propane gas pressure must

be 8.8 inch W.C at the unit under full load. Maintaining proper

gas pressure depends on three main factors:

1. The vaporization rate which depends on (a) the tempera-

ture of the liquid and (b) the wetted surface area of the

container or containers.

2. The proper pressure regulation. (Two-stage regulation is

recommended from the standpoint of both cost and effi-

ciency.)

FIGURE 6 : EXTERNAL SUPPLY CONNECTION

EXTERNAL SHUT-OFF

3. The pressure drop in the lines between regulators and

between the second stage regulator and the appliance.

Pipe size required will depend on the length of the pipe

run and the total load of all appliances.

Complete information regarding tank sizing for vaporization,

recommended regulator settings, and pipe sizing is available

from most regulator manufacturers and L.P./propane gas

suppliers.

Natural gas may contain some propane. Propane,

being an excellent solvent, will quickly dissolve

white lead or most standard commercial com-

pounds. Therefore, a special pipe compound must

be applied when wrought iron or steel pipe is used.

Shellac base compounds such as Gaskolac or

Stalastic, and compounds such as Rectorseal #5,

Cyde's or John Crane may be used.

L.P./propane gas is an excellent solvent and special pipe

compound must be used when assembling piping for this gas

as it will quickly dissolve white lead or most standard com-

mercial compounds. Shellac base compounds such as Rec-

torseal #5 are satisfactory for this type of gas.

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Check all connections for leaks when piping is completed,

using a soap solution. NEVER USE A FLAME.

The outdoor and return air dampers, the damper actuator, the

damper linkage, the outdoor and return air divider baffles,

and all the control sensors are factory mounted as part of the

Factory installed economizer option.

VENT AND COMBUSTION AIR HOODS

ENTHALPY SET POINT ADJUSTMENT

Two vent hoods and a combustion air hood (with screens) are

shipped attached to the blower housing in the blower com-

partment. These hoods must be installed to assure proper

unit function. All hoods must be fastened to the outside of the

gas heat access panel with the screws provided in the bag

also attached to the blower housing.

Remove the economizer access panel from the unit to check

the following adjustments. Loosen but do not remove the two

panel latches.

The screen for the combustion air intake hood is secured as

shown on the label attached to the hood. The top flange of

this hood slips in under the top of the access panel opening

when installing. Refer to Figure 8.

Extreme care must be exercised in turning both

the setpoint and minimum position adjusting

screws to prevent twisting them off.

Each vent hood is installed by inserting the top flange of the

hood into the slotted opening in the access panel and secur-

ing in place.

1. The enthalpy set point may now be set by selecting the

desired setpoint shown in Figure 9. Adjust as follows:

•

For a single enthalpy operation, carefully turn the set

point adjusting screw to the A, B, C or D setting corre-

sponding to the lettered curve.

•

For a dual enthalpy operation, carefully turn the set point

adjusting screw fully clockwise past the D setting.

SLOTTED

OPENINGS IN

ACCESS PANEL

2. To check that the damper blades move smoothly without

binding, carefully turn the minimum position adjusting

screw fully clockwise and then energize and de-energize

terminals R to G. With terminals R to G energized, turn

the minimum position screw counterclockwise until the

desired minimum position has been attained.

VENT AIR

OUTLET

HOODS

3. Replace the economizer access panel. Reposition the

two latches horizontally and retighten the screws.

COMBUSTION

AIR INTAKE

HOOD

POWER EXHAUST/BAROMETRIC RELIEF DAMPER

AND RAIN HOOD OPTION

GAS HEAT

ACCESS

PANELS

The instructions for the power exhaust/barometric relief

damper and rain hood can be found in form 44-320-10. The

exhaust fan, all supporting brackets, angles, and the wiring

are factory installed as part of the power exhaust option.

FIGURE 8 : VENT AND COMBUSTION AIR

HOODS

All of the components, including the dampers, hardware, and

mounting instructions are shipped in a single package exter-

nal from the unit. The hood must be field assembled and

installed.

OPTIONAL ECONOMIZER/MOTORIZED DAMPER

RAIN HOOD

Power exhaust is not available as a field installed option.

The instruction for the optional economizer/motorized

damper rain hood can be found in form 44-320-2. Use these

instructions when field assembling an economizer rain hood

onto a unit.

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FIGURE 9 : ENTHALPY SETPOINT ADJUSTMENT

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TABLE 7: DHG VOLTAGE LIMITATIONS¹

TABLE 6: PHYSICAL DATA

DHG

VOLTAGE

MODELS

POWER SUPPLY

MIN.

180

240

MAX.

253

Centrifugal Blower (Dia. x Wd. in.)

15 x 15 18 x 15

EVAPORATOR

BLOWER

208/230-3-60

460-3-60

187

414

518

Fan Motor HP

Rows Deep

7.5

506

575-3-60

EVAPORATOR

COIL

Fins Per Inch

13.5

15.5

13.5

20.0

Utilization Range “A” in accordance with ARI Standard

110.

Face Area (Sq. Ft.

Propeller Dia. (in.) (Each)

Fan Motor Hp (Each)

CONDENSER

FANS

(Two Per Unit)

Nom. CFM (Each)

5765

7000

TABLE 8: MINIMUM CLEARANCES

Rows Deep (Each)

CONDENSER

COILS

(Two Per Unit)

LOCATION

CLEARANCE

Fins Per Inch (Each)

36”

Front

Face Area (Sq. Ft.) (Total)

10-Ton Tandem Hermetic Recip.

5-Ton Hermetic Recip.

Quantity Per Unit (16” X 20” X 2”)

Quantity Per Unit (16” X 25” X 2”)

Quantity Per Unit (18” X 24” X 2”)

Total Face Area (sq. ft.)

36.0

43.3

24” (Less Economizer)

49” (With Economizer

Back

COMPRESSOR

(Qty. Per Unit)

24” (Less Economizer)

36” (With Economizer)

Left Side (Filter Access)

Right Side (Cond. Coil)

36”

0”

AIR

FILTERS

Below Unit

72” With 36” Maximum

Horizontal Overhang (For

Condenser Air Discharge)

15.0

29/9

14/8

2100

2140

20.0

Above Unit

System #1

Refrigerant 22

CHARGE

(lbs./oz.)

System #2

240Mbh (lbs)

320Mbh (lbs)

23/12

2300

2340

Units may be installed on combustible floors made

from wood or class A, B, or C roof covering material.

BASIC

UNIT

DHG

(Gas/Electric)

Units must be installed outdoors. Overhanging struc-

tures or shrubs should not obstruct condenser air dis-

charge outlet.

Economizer (lbs)

160

245

150

Economizer with

Power Exhaust (lbs)

OPTIONS

Motorized Damper (lbs)

Roof Curb (lbs)

175

185

ACCY.

Barometric Damper (lbs)

Wood Skid (lbs)

220

This compressor will be energized first.

TABLE 9: DHG ELECTRICAL DATA

COMPRESSORS

COND. FAN

MOTORS

(#1 & #2)

SUPPLY AIR

BLOWER

MOTOR

MIN.

MAX. TIME

DELAY FUSE

SIZE (AMPS)

POWER

SUPPLY

#1 #2

CIRCUIT

AMPACITY

(AMPS)

MIN. WIRE

MODEL

SIZE 75°C

FLA

(ea.)

RLA

LRA

RLA

LRA

FLA

(ea.)

208/230-3-60

460-3-60

28.6

14.4

11.4

28.6

14.4

11.4

274

138

116

274

138

116

14.3

7.2

137

4.1/4.2

2.1

11.8

5.9

77.8/77.0

42.7

DHG180

575-3-60

5.7

1.4

5.2

30.7

208/230-3-60

460-3-60

28.6

14.4

11.4

274

138

116

4.1/4.2

2.1

7.5

18.6

9.3

98.6/96.8

52.2

110

DHG240

575-3-60

1.4

7.5

40.2

Although these sizes are based on copper conductors aluminum wire can be used. Refer to the national electric code (in USA) or

the current Canadian Electrical Code (in Canada) to determine the proper size.

Unitary Products

035-17233-000-C-0702

ECONOMIZER / MOTORIZED DAMPER,

FIXED OUTDOOR INTAKE AIR AND

POWER EXHAUST RAIN HOODS

(See detail "Y")

BLOWER

ACCESS

FIELD-SUPPLIED

DISCONNECT SWITCH

LOCATION

BLOWER MOTOR

ACCESS

COMPRESSOR

ACCESS

BLOWER

COMPARTMENT

ACCESS

(Auxiliary)

OPTIONAL COIL

GUARD KIT

DOT PLUG

(For pressure

Drop Reading)

48-5/8" (15 Ton)

52-5/8" (20 Ton)

GAS HEAT

ACCESS

CONDENSER

COILS

VENT AIR

OUTLET

HOODS

21"

7-1/8"

COMBUSTION

AIR INLET

HOOD

125-1/4" (15 Ton)

136-1/4" (20 Ton)

6-3/8"

9-3/4"

5-7/8"

92"

(C)

(A)

GAS SUPPLY

CONTROL WIRING

ENTRY

46-5/8"

CONTROL BOX

ACCESS

11-1/2"

(B)

35"

POWER WIRING

ENTRY

BOTTOM SUPPLY

AND RETURN

AIR OPENINGS

(See Note)

FRONT

VIEW

24-1/4" (15 Ton)

35-1/4" (20 Ton)

RETURN AIR

SUPPLY AIR

OUTDOOR AIR

RETURN

AIR

3-3/4"

33"

SUPPLY

AIR

2-3/4"

21-1/2"

11-1/8"

OUTDOOR AIR

(Economizer)

UNIT BASE WITH RAILS

(B)

(D)

Shown separately to illustrate

Bottom Duct openings, Power

and Gas Piping Connection

locations

POWER WIRING

ENTRY

GAS SUPPLY

ENTRY

All dimensions are in inches. They are

subject to change without notice. Certi-

fied dimensions will be provided upon

request.

(A)

CONTROL WIRING

ENTRY

8-1/8"

9-3/4"

NOTE:

46-5/8"

For curb mounted units, refer to the curb hanger

dimensions of the curb for the proper size of the

supply and return air duct connections.

9-1/4"

12-1/2"

FIGURE 10 : UNIT DIMENSIONS DHG180 & 240 (FRONT VIEW)

(

)

(

)

(

)

FIGURE 11 : UNIT DIMENSIONS DHE/DHG180 & 240 (RAINHOOD)

Unitary Products

035-17233-000-C-0702

(

)

(

)

FIGURE 12 : UNIT DIMENSIONS DHE/DHG180 & 240 (REAR VIEW)

NOTE: A 1” clearance must be provided between any com-

bustible material and the supply air ductwork for a distance of

3 feet from the unit.

2. Remove and discard the bottom duct covers. (Duct

openings are closed with sheet metal covers except

when the unit includes a power exhaust option. The cov-

ering consists of a heavy black paper composition.)

NOTE: The products of combustion must not be allowed to

accumulate within a confined space and recirculate.

TABLE 10: UTILITIES ENTRY

OPENING SIZE

HOLE

USED FOR

NOTE: Locate unit so that the vent air outlet hood is at least:

(DIA.)

1-1/8” KO

Front

•

Three (3) feet above any force air inlet located within 10

horizontal feet (excluding those integral to the unit).

Control Wiring

3/4” NPS (Fem.)

3-5/8” KO

Bottom

Front

Bottom

Power Wiring

Four (4) feet below, 4 horizontal feet from, or 1 foot

above any door or gravity air inlet into the building.

3” NPS (Fem.)

2-3/8” KO

Gas Piping (Front)

1-11/16” Hole

Four (4) feet from electric and gas meters, regulators

and relief equipment

Gas Pipping (Bottom)

1” Gas Piping MPT Required.

NOTE: All entry holes should be field sealed to prevent rain

water entry into building

Opening in the bottom to the unit can be located by the

side in the insulation.

3. Replace the side supply and return air compartment pan-

els.

Duct Covers - Units are shipped with the bottom duct open-

ings covered. An accessory flange kit is available for con-

necting side ducts.

For side duct applications:

For bottom duct applications:

1. Replace the side panels on the supply and return air

compartments with the accessory flange kit panels.

1. Remove the side panels from the supply and return air

compartments.

2. Connect ductwork to the duct flanges on the rear of the

unit.

Unitary Products

035-17233-000-C-0702

TABLE 11: DHG 15 TON SUPPLY AIR BLOWER PERFORMANCE

1, 2

DHG180 - BOTTOM DUCT CONNECTIONS

MOTOR

PULLEY

(TURNS

CFM

BLOWER

SPEED,

(RPM)

4500

BHP

5250

BHP

6000

6750

BHP

7200

BHP

ESP

OPEN)

208 VOLT AND STANDARD DRIVE

850

870

0.9

1.0

1.1

1.2

1.3

1.4

1.6

2.4

2.5

2.6

2.7

2.9

3.0

3.2

2.1

2.2

2.4

2.5

2.6

2.7

2.9

0.6

0.7

0.8

0.9

1.0

1.1

1.3

2.9

3.0

3.1

3.2

3.4

3.6

3.8

2.6

2.7

2.8

2.9

3.0

3.2

3.4

0.3

0.4

0.5

0.6

0.7

0.8

1.0

3.4

3.5

3.6

3.7

3.8

4.0

4.4

3.0

3.1

3.2

3.3

3.4

3.6

3.9

6.0

5.5

4.5

3.5

3.0

2.0

1.0

915

0.2

0.4

0.5

0.6

0.8

4.1

4.4

4.5

4.7

5.0

3.7

3.9

4.0

4.2

4.5

965

0.2

0.3

0.4

0.6

5.0

5.1

5.4

5.6

4.5

4.6

4.8

5.0

980

1010

1040

FIGURE 13 : 208 VOLT AND HIGH SPEED DRIVE ACCESSORY

965

6.0

5.5

4.5

3.5

2.0

1.0

1.2

1.3

1.4

1.6

1.9

2.1

2.7

2.9

3.1

3.4

3.6

3.9

2.5

2.6

2.8

3.0

3.2

3.5

0.9

1.0

1.2

1.4

1.7

1.9

3.2

3.4

3.6

3.9

4.4

4.7

2.9

3.0

3.2

3.5

3.9

4.2

0.6

0.7

0.9

1.1

1.4

1.6

3.7

3.8

4.1

4.5

5.0

5.5

3.3

3.4

3.7

4.0

4.5

4.9

0.4

0.5

0.7

0.9

1.2

4.4

4.5

4.8

5.1

5.8

3.9

4.0

4.3

4.6

5.2

0.2

0.3

0.4

5.0

5.1

5.5

4.5

4.6

4.9

980

1025

1065

1125

1170

230/460 VOLT AND STANDARD DRIVE

870

915

1.0

1.1

1.2

1.3

1.4

1.5

1.6

2.5

2.6

2.7

2.9

3.0

3.1

3.4

2.2

2.4

2.5

2.6

2.7

2.8

3.0

0.7

0.8

0.9

1.0

1.1

1.2

1.4

3.0

3.1

3.2

3.4

3.6

3.7

3.9

2.7

2.8

2.9

3.0

3.2

3.3

3.5

0.4

0.5

0.6

0.7

0.8

0.9

1.1

3.5

3.6

3.7

3.8

4.0

4.2

4.5

3.1

3.2

3.3

3.4

3.6

3.8

4.0

6.0

5.0

4.0

3.5

2.5

1.5

1.0

0.2

0.4

0.5

0.6

0.7

0.9

4.1

4.4

4.5

4.7

4.9

5.1

3.7

3.9

4.0

4.2

4.4

4.6

965

0.2

0.3

0.4

0.5

5.0

5.1

5.4

5.7

4.5

4.6

4.8

5.1

980

1015

1050

1065

230/460 VOLT AND HIGH SPEED DRIVE ACCESSORY

980

6.0

4.5

4.0

2.5

1.5

1.0

1.3

1.6

1.7

1.9

2.1

2.2

2.9

3.2

3.4

3.6

3.9

4.0

2.6

2.9

3.0

3.2

3.5

3.6

1.0

1.3

1.4

1.7

1.8

1.9

3.4

3.8

3.9

4.4

4.7

4.8

3.0

3.4

3.5

3.9

4.2

4.3

0.7

1.0

1.1

1.4

1.6

1.7

3.8

4.4

4.5

5.0

5.5

5.6

3.4

3.9

4.0

4.5

4.9

5.0

0.5

0.8

0.9

1.2

4.5

5.0

5.1

5.8

4.0

4.5

4.6

5.2

0.3

5.1

4.6

1045

1065

1125

1170

1190

0.6

5.6

5.0

Blower performance includes a gas -fired heat exchanger, fixed outdoor air, 2” T/A filters and a dry evaporator coil.

Refer to the Static Resistance table.

DO NOT close the pulley below one turn open.

ESP = External Static Pressure available for the supply and return air duct system. All internal unit resistances have been

deducted from the total static pressure of the blower.

The factory setting.

Unitary Products

035-17233-000-C-0702

TABLE 12: DHG 20 TON SUPPLY AIR BLOWER PERFORMANCE

1, 2

DHG240 - BOTTOM DUCT CONNECTIONS

MOTOR

PULLEY

(TURNS

CFM

BLOWER

SPEED,

(RPM)

6000

BHP

7000

BHP

8000

9000

BHP

9400

BHP

ESP

OPEN)

208 VOLT AND STANDARD DRIVE

870

900

930

950

980

995

1015

1.3

1.4

1.6

1.7

1.9

2.1

2.2

3.6

3.8

4.1

4.2

4.5

4.6

4.8

3.0

3.2

3.4

3.6

3.8

3.9

4.0

0.7

0.9

1.1

1.3

1.5

1.6

1.7

4.3

4.7

5.0

5.1

5.4

5.5

5.7

3.7

4.0

4.2

4.3

4.5

4.7

4.8

0.2

0.4

0.6

0.8

1.0

1.1

1.2

5.1

5.6

5.9

6.0

6.3

6.4

6.6

4.3

4.7

5.0

5.1

5.3

5.4

5.6

6.0

5.0

4.0

3.0

2.0

1.5

1.0

0.1

0.2

0.4

0.5

0.7

6.7

6.9

7.2

7.5

7.8

5.7

5.8

6.1

6.3

6.6

0.1

0.2

8.5

8.6

7.1

7.3

208 VOLT AND HIGH SPEED DRIVE ACCESSORY

950

980

6.0

5.0

4.5

3.5

2.5

2.0

1.0

1.7

1.9

2.1

2.3

2.5

2.6

2.9

4.2

4.5

4.6

4.9

5.1

5.3

5.6

3.6

3.8

3.9

4.1

4.3

4.4

4.7

1.3

1.5

1.6

1.8

2.0

2.1

2.3

5.1

5.4

5.5

5.8

6.1

6.3

6.8

4.3

4.5

4.7

4.9

5.1

5.3

5.7

0.8

1.0

1.1

1.3

1.4

1.5

1.8

6.0

6.3

6.4

6.7

7.1

7.3

7.9

5.1

5.3

5.4

5.7

6.0

6.2

6.6

0.2

0.4

0.5

0.7

0.9

1.0

6.9

7.2

7.5

8.0

8.4

8.6

5.8

6.1

6.3

6.7

7.0

7.2

0.1

8.5

7.1

995

0.2

8.6

7.3

1025

1050

1065

1100

230/460 VOLT AND STANDARD DRIVE

870

900

1.3

1.4

1.6

1.7

1.9

2.1

2.2

2.3

3.6

3.8

4.1

4.2

4.5

4.6

4.8

4.9

3.0

3.2

3.4

3.6

3.8

3.9

4.0

4.1

0.7

0.9

1.1

1.3

1.5

1.6

1.7

1.8

4.3

4.7

5.0

5.1

5.4

5.5

5.7

5.8

3.7

4.0

4.2

4.3

4.5

4.7

4.8

4.9

0.2

0.4

0.6

0.8

1.0

1.1

1.2

1.3

5.1

5.6

5.9

6.0

6.3

6.4

6.6

6.7

4.3

4.7

5.0

5.1

5.3

5.4

5.6

5.7

6.0

5.0

4.0

3.5

2.5

2.0

1.5

1.0

930

0.1

0.2

0.4

0.5

0.6

0.7

6.7

6.9

7.2

7.5

7.8

8.0

5.7

5.8

6.1

6.3

6.6

6.7

950

965

0.1

0.2

8.5

8.6

7.1

7.3

995

1015

1025

230/460 VOLT AND HIGH SPEED DRIVE ACCESSORY

950

980

6.0

5.0

4.5

4.0

3.5

3.0

2.5

1.5

1.0

1.7

1.9

2.1

2.2

2.3

2.5

2.6

2.9

3.1

4.2

4.5

4.6

4.8

4.9

5.1

5.3

5.6

5.8

3.6

3.8

3.9

4.0

4.1

4.3

4.4

4.7

4.9

1.3

1.5

1.6

1.7

1.8

2.0

2.1

2.3

2.5

5.1

5.4

5.5

5.7

5.8

6.1

6.3

6.8

7.0

4.3

4.5

4.7

4.8

4.9

5.1

5.3

5.7

5.9

0.8

1.0

1.1

1.2

1.3

1.4

1.5

1.8

1.9

6.0

6.3

6.4

6.6

6.7

7.1

7.3

7.9

8.3

5.1

5.3

5.4

5.6

5.7

6.0

6.2

6.6

6.9

0.2

0.4

0.5

0.6

0.7

0.9

1.0

6.9

7.2

7.5

7.8

8.0

8.4

8.6

5.8

6.1

6.3

6.6

6.7

7.0

7.2

0.1

8.5

7.1

995

0.2

8.6

7.3

1015

1025

1050

1065

1100

1120

Blower performance includes a gas -fired heat exchanger, fixed outdoor air, 2” T/A filters and a dry evaporator coil.

Refer to the Static Resistance table.

DO NOT close the pulley below one turn open.

ESP = External Static Pressure available for the supply and return air duct system. All internal unit resistances have been

deducted from the total static pressure of the blower.

The Factory Setting

Unitary Products

035-17233-000-C-0702

TABLE 13: STATIC RESISTANCES¹

RESISTANCE, IWG

CFM

DESCRIPTION

15 TON

5765

0.1

20 TON

7000

0.1

4500

7200

0.1

6000

9400

0.1

WET COIL

0.1

0.2

0.1

0.2

ECONOMIZER OPTION

0.1

0.3

0.5

0.3

0.5

HORIZONTAL DUCT CONN.

Deduct these resistance values from the available unit ESP values listed in the respective blower per-

formance table except for Horizontal Duct Connections.

Add these values due to less airflow resistance.

TABLE 14: POWER EXHAUST PERFORMANCE

STATIC RESISTANCE OF RETURN DUCTWORK, IWG

MOTOR

0.2

0.3 0.4 0.5

0.6

SPEED

CFM

5250

4900

4400

0.83

0.77

0.72

CFM

4500

3900

3700

0.85

0.79

0.74

CFM

4200

3500

3000

0.88

0.82

0.78

CFM

3750

2900

0.93

0.85

CFM

3000

0.99

HIGH

MEDIUM

LOW

Power exhaust motor is a 3/4 HP, PSC type with sleeve bearings, a 48 frame and inherent protection.

The factory setting.

TABLE 15: BLOWER MOTOR AND DRIVE DATA

BELT

(NOTCHED)

ADJ. MOTOR PULLEY

FIXED BLOWER PULLEY

MOTOR

BLWR

DRIVE RANGE

(RPM)

MODEL

SIZE

PITCH

DIA

(in.)

PITCH

DIA

(in.)

PITCH

LNGTH. QTY.

(in.)

EFF. DESIGN- O/D

(%) NATION (in.)

BORE DESIGN- O/D

BORE DESIG-

HP FRAME

(in.)

NATION

(in.)

NATION

Std.

850/1065

965/1190

870/1025

950/1120

BK90

8.75

8.4

BX70

71.8

69.8

84.8

81.8

4.3-

High

Spd.

Acs.

15 Ton

20 Ton

184T

213T

89.5

1VP56

1VP68

5.35

6.75

1-1/8

5.3

BK80

BK120

BK110

7.75

7.4

BX68

BX83

BX80

Std.

11.75 11.4 1-3/16

10.75 10.4 1-3/16

5.5-

High

Spd.

Acs.

7.5

1-3/8

6.5

All motors have a nominal speed of 1800 RPM, a 1.15 service factor and a solid base. They can operate to the limit of their service

factor because they are located in the moving air, upstream of any heating device.

DO NOT close this pulley below 1 turn.

Unitary Products

035-17233-000-C-0702

modulate to maintain a constant supply air temperature as

monitored by the discharge air sensor. If the outdoor air

enthalpy is above the setpoint, Y1 energizes compressor #1,

condenser fan motor #1, and condenser fan motor #2 (if the

ambient temperature is above 60°F).

OPERATION

COOLING SYSTEM

The cooling section is a complete factory package utilizing an

air-cooled condenser. The system is factory-charged with

Refrigerant-22.

When the thermostat calls for second-stage cooling, the low

voltage control circuit from R to Y2 is completed. If the

enthalpy of the outdoor air is below the setpoint of the

enthalpy controller (i.e. first stage has energized the econo-

mizer), Y2 will energize compressor #1. If the outdoor air is

above the setpoint, Y2 will energize compressor #2.

The compressors are hermetically sealed, internally sprung

and base-mounted with rubber-insulated hold-down bolts.

Compressors have inherent (internal) protection. If there is an

abnormal temperature rise in a compressor, the protector will

open to shut down the compressor.

After the thermostat is satisfied and opens, all components

will stop simultaneously. The blower motor will continue to

operate if the fan switch on the room thermostat is set in the

ON position.

PRELIMINARY OPERATION COOLING

After installation has been completed, energize the crank-

case heaters for at least four hours before operating the unit.

After the initial installation, the compressors should be given

three false starts (energized just long enough to make a few

revolutions) with 5-7 minutes delay between each start,

before being put into full time service.

ECONOMIZER WITH DUAL ENTHALPY SENSORS

The operation with the dual enthalpy sensors is identical to

the single sensor except that a second enthalpy sensor is

mounted in the return air. This return air sensor allows the

economizer to choose between outdoor air and return air,

whichever has the lowest enthalpy value, to provide maxi-

mum operating efficiency.

NOTE: Prior to each cooling season, the crankcase heaters

must be energized at least 8 hours before system is put into

operation.

ECONOMIZER (SINGLE OR DUAL) WITH POWER

EXHAUST

COOLING SEQUENCE OF OPERATION

NO OUTDOOR AIR OPTIONS

This system operates as specified above with one addition.

The power exhaust motor is energized whenever the econo-

mizer is chosen by the enthalpy sensor for first stage cooling,

Y1. As always, the R to G connection provides minimum

position but does not provide power exhaust operation.

When the room thermostat calls for first-stage cooling, the

low voltage control circuit from R to G and Y1 is completed to

energize compressor #1, condenser fan motor #1, condenser

fan motor #2 (if the ambient temperature is above 60F), and

the supply air blower motor (if the fan switch on the room

thermostat is set in the AUTO position).

MOTORIZED OUTDOOR AIR DAMPERS

This system operation is the same as the units with no out-

door air options with one exception. When the R to G circuit is

complete, the motorized damper drives open to a position set

by the thumbwheel on the damper motor. When the R to G

circuit is opened, the damper spring returns fully closed.

When the thermostat calls for second-stage cooling, the low

voltage control circuit from R to Y2 is completed to energize

compressor #2.

CONTINUOUS BLOWER

After the thermostat is satisfied and opens, all components

will stop simultaneously. The blower motor will continue to

operate if the fan switch on the room thermostat is set in the

ON position.

Continuous blower operation is possible by closing the R to G

circuit on the thermostat.

SAFETY CONTROLS

ECONOMIZER WITH SINGLE ENTHALPY SENSOR

1. A Suction Line Freezestat to protect against low evapo-

rator temperatures due to a low air flow or a low return

air temperature. (Opens at 26°F + 5°F and resets at 38°F

+ 5°F)

When the room thermostat calls for first-stage cooling, the

low voltage control circuit from R to G and Y1 is completed.

The R to G circuit energizes the blower motor (if the fan

switch on the room thermostat is set in the AUTO position)

and drives the economizer dampers from fully closed to their

minimum position. If the enthalpy of the outdoor air is below

the setpoint of the enthalpy controller (previously

determined), Y1 energizes the economizer. The dampers will

2. A High Pressure Cutout Switch to protect against exces-

sive discharge pressures due to a blocked condenser

coil or a condenser motor failure. (Opens at 380 psig +

10 and resets at 300 psig +10)

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3. A Low Pressure Switch/Loss Of Charge to protect

against loss of refrigerant charge. (Opens at 7 psig + 3

and resets at 22 psig + 5)

Gas flows into each of the main burners and is ignited from

the carryover tube flame.

If IC1 fails to detect a pilot flame, it will continue to try for a

maximum of 85 seconds to ignite the pilot tube. If the pilot

flame is not detected, then IC1 will lock out first stage furnace

operation until 24V power is removed from the module either

at the unit or by resetting the room thermostat.

If either one of the above safety controls opens, that individ-

ual refrigerant system will be locked out. The other refrigerant

system will continue in operation unless it too is effected by

the same fault. The lock out of either system can be reset by

opening the 24V circuit either at the room thermostat or at the

unit disconnect.

At the same time power was supplied to the RW1, a parallel

circuit activates ETD which closes the ETD contact after

approximately 35 seconds and energizes K5 which closes

K5-2 and starts the blower by energizing M3.

HEATING SYSTEM

The following sequence describes the operation of the gas

heat section.

When TH2 closes, heat relay RW2 is energized. The RW2-1

contact is closed energizing the second stage ignition module

IC2. IC2 will immediately start the second stage ignitor spark-

ing and will open the redundant valve located inside the sec-

ond stage main gas valve GV2 to allow a flow of gas to the

second stage carryover tube. See Figure 11. Only after the

pilot flame has been ignited and the presence of pilot flame

detected at IC2 by a signal sent back through the flame sen-

sor is sparking terminated and the main gas valve opened.

CONTINUOUS BLOWER

With the room thermostat switch set to ON, the supply air

blower will operate continuously. The normally closed contact

K5-1 provides 24 volt power to the M3 contactor. The M3-1, 2

& 3 power contacts close and the blower motor operates.

INTERMITTENT BLOWER

With the room thermostat system switch set to the AUTO or

HEAT position and the fan switch set to AUTO, the supply air

blower will operate after the room thermostat calls for heat

and the time delay relay closes.

Gas flows into each of the second stage main burners and is

ignited from the carryover tube flame.

If IC2 fails to detect a pilot flame, it will continue to try for a

maximum of 85 seconds to ignite the pilot tube. If the pilot

flame is not detected, then IC2 will lock out first stage furnace

operation until 24V power is removed from the module either

at the unit or by resetting the room thermostat. Note that the

second stage furnace can operate even if first stage has

locked out.

The TH1 closes, the heat relay RW1 is energized. The RW1-

1 power contact closes energizing the line voltage draft

motor. The RW1-2 contact is also closed. As the speed of the

draft motor reaches approximately 2500 RPM, the centrifugal

switch contact located on the end of the draft motor shaft

closes to power the first stage ignition module IC1.

When the heating cycle is complete, TH2 opens de-energiz-

ing the RW2 then TH1 opens de-energizing RW1 and ETD,

thus closing all gas valves. The blower motor will continue to

run (approximately 45 seconds after the furnace is shut

down) until ETD opens, de-energizing the K5 relay and M3

contactor.

REDUNDANT

VALVE

MAIN VALVE

GAS MAIN

SAFETY CONTROLS

GAS

VALVE

TO MAIN

BURNER

The control circuit includes the following safety controls:

TO PILOT BURNER

1. Limit Control (LS). This control is located inside the heat

exchanger compartment and is set to open at the tem-

perature indicated in Table 16. It resets automatically.

The limit switch operates when a high temperature con-

dition, caused by inadequate supply air flow occurs, thus

shutting down the ignition control and closing the main

gas valves and energizing the blower.

FIGURE 14 : GAS VALVE PIPING

Ignition module IC1 will immediately start the first stage igni-

tor sparking and will open the redundant valve located inside

the first stage main gas valve GV1 to allow a flow of gas to

only the first stage carryover tube. See Figure 14. Only after

the pilot flame has been ignited and the presence of pilot

flame detected at the IC1 by a signal sent back through the

flame sensor is sparking terminated and the first stage main

gas valve opened.

2. Centrifugal Switch (CS). If the draft motor should fail, the

centrifugal switch attached to the shaft of the motor pre-

vents the ignition controls and gas valves from being

energized.

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TABLE 16: LIMIT CONTROL SETTING

Capacity, MBH

Units

Limit

Control

Opens, °F

(Tons)

Input

Output

15 & 20

300

400

240

320

195

HEAT ANTICIPATOR SETPOINTS

It is important that the anticipator setpoint be correct. Too

high of a setting will result in longer heat cycles and a greater

temperature swing in the conditioned space. Reducing the

value below the correct setpoint will give shorter ON cycles

and may result in the lowering of the temperature within the

conditioned space.

TABLE 17: HEAT ANTICIPATOR SETPOINT

Gas Valve

1st Stage

2nd Stage

FIGURE 15 : GAS VALVE AND CONTROLS

Honeywell VR8440

0.30 amp

0.11 amp

3. Redundant Gas Valve - There are two separate gas

valves in the furnace. Each valve contains a main and a

redundant valve. The redundant valves are located

upstream of the main gas valves. Should either or both

of the main gas valves fail in the open position the redun-

dant valves serve as back-ups and shuts off the flow of

gas.

White-Rodgers 36C68

START UP

PRE-START CHECK LIST

Complete the following checks before starting the unit.

4. Flame Sensor Rod / 100% Ignition Control Lock-Out -

The flame rods and controls are located per Figure 15. If

an ignition control fails to detect a signal from the flame

sensor indicating the pilot flame is properly ignited, then

the main gas valve will not open. It will continue to try

and ignite the pilot for a maximum of 85 seconds, then if

the pilot flame is not detected, the ignition control will

lock out furnace operation until 24V power is removed

from the module either at the unit or by resetting the

room thermostat.

1. Check the type of gas being supplied. Be sure that it is

the same as listed on the unit nameplate.

2. Make sure that the vent and combustion air hoods have

been properly installed.

OPERATING INSTRUCTIONS

5. Rollout Switch - This switch is located above the main

burners in the control compartment which in the event of

a sustained main burner rollout shuts off and locks out

both ignition controls closing both gas valves. The igni-

tion controls lock out furnace operation until 24V power

is removed from the controls either at the unit or by

resetting the room thermostat. Note the auto reset rollout

switch must reset before allowing furnace operation.

This furnace is equipped with an intermittent pilot

and automatic re-ignition system. DO NOT attempt

to manually light the pilot.

TO LIGHT PILOT AND MAIN BURNERS:

1. Turn off electric power to unit.

6. Auxiliary limit switch (AUX) - This control is located

inside the heat exchanger compartment and is set to

open at 190F. It is a manual reset switch. If AUX limit

trips, then the primary limit has not functioned correctly.

Replace the primary limit switch.

2. Turn room thermostat to lowest setting.

3. Turn gas valve knob to on position.

4. Turn on electric power to unit.

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5. Set room thermostat to desired temperature.(If thermo-

stat set temperature is above room temperature, pilot

burner ignition will occur and, after an interval to prove

pilot flame, main burners will ignite).

Adjust as follows:

1. Remove the cap on the regulator. It's located next to the

push-on electrical terminals.

TO SHUT DOWN:

2. To decrease the gas pressure, turn the adjusting screw

counterclockwise.

1. Turn off electric power to unit.

2. Depress knob of gas valve while turning to off position.

3. To increase the gas pressure, turn the adjusting screw

clockwise.

NOTE: The correct manifold pressure for these furnaces is

3.5 IWG 0.3.

POST-START CHECK LIST (GAS)

After the entire control circuit has been energized and the

heating section is operating, make the following checks:

PILOT CHECKOUT

1. Check for gas leaks in the unit piping as well as the sup-

ply piping.

The pilot flame should envelope the end of the flame sensor.

Refer to Figure 16. To adjust pilot flame, (1) remove pilot

adjustment cover screw, (2) increase or decrease the clear-

ance for air to the desired level, (3) be sure to replace cover

screw after adjustment to prevent possible gas leakage.

2. Check for correct manifold gas pressures. See Checking

Gas Input.

3. Check the supply gas pressure. It must be within the lim-

its shown on rating nameplate. Supply pressure should

be checked with all gas appliances in the building at full

fire. At no time should the standby gas line pressure

exceed 13", nor the operating pressure drop below 5.0"

for natural gas units. If gas pressure is outside these lim-

its, contact the local gas utility for corrective action.

Put the system into operation and observe through complete

cycle to be sure all controls function properly.

MANIFOLD GAS PRESSURE ADJUSTMENT

Small adjustments to the high-fire gas flow may be made by

turning the pressure regulator adjusting screw on the auto-

matic gas valve. Refer to Figure 16.

On-Off Control

High Fire Adj.

FIGURE 17 : PROPER FLAME ADJUSTMENT

BURNER INSTRUCTIONS

(Under Screw)

To check or change burners, pilot or orifices, CLOSE MAIN

MANUAL SHUT-OFF VALVE AND SHUT OFF ALL ELEC-

TRIC POWER TO THE UNIT.

1. Remove the screws holding either end of the manifold to

the burner supports.

2. Open the union fitting in the gas supply line just

upstream of the unit gas valve and downstream from the

main manual shut-off valve.

3. Remove the gas piping closure panel.

Pilot Adj.

(Under Screw)

4. Disconnect wiring to the gas valves and spark ignitors.

Remove the manifold-burner gas valve assembly by lift-

ing up and pulling back.

FIGURE 16 : TYPICAL GAS VALVE

Burners are now accessible for service.

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Reverse the above procedure to replace the assemblies.

Make sure that burners are level and seat at the rear of the

heat exchanger.

BURNER AIR SHUTTER ADJUSTMENT

Adjust burner shutters so no yellow flame is observed in the

heat exchanger tubes. Refer to Figure 17.

CHECKING SUPPLY AIR CFM

The RPM of the supply air blower will depend on the required

CFM, the unit accessories or options and the static resis-

tances of both the supply and the return air duct systems.

With this information, the RPM for the supply air blower and

the motor pulley adjustment (turns open) can be determined

from the blower performance data in Tables 11 and 12.

High speed drive accessories (containing a smaller blower

pulley and a shorter belt) are available for applications requir-

ing the supply air blower to produce higher CFM's and/or

higher static pressures. Use Model 1LD0416 for 15 ton units

and Model 1LD0417 for 20 ton units. Refer to Table 15 for

blower motor and drive data.

FIGURE 19 : BELT ADJUSTMENT

2. Insert at least 8" of 1/4 inch tubing into each of these

holes for sufficient penetration into the air flow on both

sides of the indoor coil.

NOTE: The tubes must be inserted and held in a position per-

pendicular to the air flow so that velocity pressure will not

affect the static pressure readings.

FIGURE 18 : TYPICAL FLAME APPEARANCE

3. Using an inclined manometer, determine the pressure

drop across a dry evaporator coil. Since the moisture on

an evaporator coil may vary greatly, measuring the pres-

sure drop across a wet coil under field conditions would

be inaccurate. To assure a dry coil, the compressors

should be deactivated while the test is being run.

Note the following:

1. The supply air CFM must be within the limitations shown

in Table 2.

2. Pulleys can be adjusted in half turn increments.

4. Knowing the pressure drop across a dry coil, the actual

CFM through the unit and clean 2" filters, can be deter-

mined from the curve in Figure 20.

3. The tension on the belt should be adjusted as shown in

Figure 19.

Start the supply air blower motor. Adjust the resistances in

both the supply and the return air duct systems to balance

the air distribution throughout the conditioned space. The job

specifications may require that this balancing be done by

someone other than the equipment installer.

After readings have been obtained, remove the tubes and

reinstall the two 5/16" dot plugs that were removed in Step 1.

To check the supply air CFM after the initial balancing has

been completed:

Failure to properly adjust the total system air quan-

tity can result in extensive blower damage.

1. Remove the two 5/16" dot plugs from the blower motor

and the filter access panels shown in Figure 10.

NOTE: De-energize the compressors before taking any test

measurements to assure a dry indoor coil.

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2. With the furnace turned on, measure the time needed for

one revolution of the hand on the smallest dial on the

meter. A typical gas meter usually has a 1/2 or a 1 cubic

foot test dial.

3. Using the number of seconds for each revolution and the

size of the test dial increment, find the cubic feet of gas

consumed per hour from Table 18.

If the actual input is not within 5% of the furnace rating (with

allowance being made for the permissible range of the regu-

lator setting), replace the orifice spuds with spuds of the

proper size.

NOTE: To find the Btu input, multiply the number of cubic feet

of gas consumed per hour by the Btu content of the gas in

your particular locality (contact your gas company for this

information - it varies widely from city to city.)

TABLE 18: GAS RATE - CUBIC FEET PER HOUR¹

FIGURE 20 : PRESSURE DROP ACROSS A DRY

INDOOR COIL VS. SUPPLY AIR CFM

SIZE OF TEST DIAL

SECONDS FOR 1 REV.

1/2 Cu. Ft.

450

300

228

180

150

129

113

100

1 Cu. Ft.

900

600

450

360

300

257

225

200

180

164

150

138

129

ADJUSTMENT OF TEMPERATURE RISE

The temperature rise (or temperature difference between the

return air and the heated air from the furnace) must lie within

the range shown on the ETL rating plate and the data in Table

After the temperature rise has been determined, the cfm can

be calculated as follows:

BtuhbInput × 0.8

-------------------------------------------------------

CFM =

1.08 × °FbTempbRise

After about 20 minutes of operation, determine the furnace

temperature rise. Take readings of both the return air and the

heated air in the ducts (about six feet from the furnace) where

they will not be affected by radiant heat. Increase the blower

cfm to decrease the temperature rise; decrease the blower

cfm to increase the rise. Refer to Table 11 for blower motor

and drive data.

Example: By actual measurement, it takes 13 seconds

for the hand on the 1-cubic foot dial to make a revolu-

tion with just a 300,000 Btuh furnace running. Read

across to the column in the table above, headed “1

Cubic Foot”, where you will see that 278 cubic feet of

gas per hour are consumed by the furnace at that rate.

Multiply 278 X 1050 (the Btu rating of the gas obtained

from the local gas company). The result is 292,425

Btuh, which is close to the 3000,000 Btuh rating of the

furnace.

BELT DRIVE BLOWER

All units have belt drive single-speed blower motors. The vari-

able pitch pulley on the blower motor can be adjusted to

obtain the desired supply air CFM. Tighten belts enough to

prevent slipping. but do not over tighten. Belt deflection

should be between 1/4" and 1/2" per foot. Refer to Table 15

for blower motor and drive data.

SECURE OWNER’S APPROVAL

CHECKING GAS INPUT

NATURAL GAS

When system is functioning properly, secure the owner’s

approval. Show him the location of all disconnect switches

and the thermostat. Teach him how to start and stop the unit

and how to adjust temperature settings within the limitations

of the system.

1. Turn off all other gas appliances connected to the gas

meter.

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If desired, every three years remove both pipe plugs at each

end shell and clean out any hardened grease or foreign mat-

ter. Replace one plug on each end with a clean grease fitting.

Using a low pressure grease gun, pump grease (Chevron

SRI-2 or equivalent) into the bearing cavity until new grease

shows at the open port. Do not over lubricate. Run the motor

for ten minutes until excess grease is purged from the cavity.

Replace the plugs.

MAINTENANCE

NORMAL MAINTENANCE

Prior to any of the following maintenance proce-

dures, shut off all electric power to the unit to pre-

vent personal injury.

On 20 ton only, units are supplied with blower shaft bearings

that do not require maintenance but may be relubricated if

desired. Every three years, using a low pressure grease gun,

pump grease into the bearing grease fitting until grease just

begins to show at the seals. Do not over lubricate. Use any

lithium base grease recommended for ball bearing service.

Periodic maintenance normally consists of changing or clean-

ing filters and (under some conditions) cleaning the main

burners

OUTDOOR COIL

FILTERS

Dirt should not be allowed to accumulate on the outdoor coil

surface or other parts in the air circuit. Cleaning should be as

often as necessary to keep coil clean. Use a brush, vacuum

cleaner attachment, or other suitable means. If water is used

to clean coil, be sure electric power to the unit is shut off prior

to cleaning.

Inspect once a month. Replace disposable or clean perma-

nent type as necessary. DO NOT replace permanent type

with disposable. The dimensional size of the replacement fil-

ter must be the same as the replaced filter.

MOTORS

NOTE: Exercise care when cleaning the coil so that the coil

fins are not damaged.

Outdoor fan motors are permanently lubricated and require

no maintenance.

NOTE: Do not permit the hot condenser air discharge to be

obstructed by overhanging structures of shrubs.

Ventor motor is factory lubricated for an estimated 10 year

life.

BURNER & PILOT

Indoor Blower Motor and Drive - The indoor blower motor fea-

tures ball bearings that do not require periodic lubrication.

Periodic lubrication of the motor and bearings can extend the

Periodically (at least annually at the beginning of each heat-

ing season) make a visual check of the pilot and main burner

flame. If necessary, adjust main burner primary air shutters to

give a distinct, sharp blue flame as explained under BURNER

AIR SHUTTER ADJUSTMENT. If it is not possible to adjust

for the proper flame, the burners may need cleaning.

life of components but is optional.

TO CLEAN BURNERS

Damage can occur if the bearings are overlubri-

cated. Use grease sparingly.

Remove them from the furnace as explained in Burner

Instructions. Clean burners with hot water applied along top

of the burner.

COMBUSTION AIR DISCHARGE

Perform all maintenance operations on the blower

motor with electric power disconnected from the

unit. Do not attempt to lubricate bearings with the

unit in operation.

Visually inspect discharge outlet periodically to make sure

that the buildup of soot and dirt is not excessive. If necessary,

clean to maintain adequate combustion air discharge.

CLEANING FLUE PASSAGES AND HEATING ELE-

MENTS

On an annual basis, check the motor for accumulations of

dust, etc. that may block the cooling slots in the motor shell.

Check for loose, damaged or misaligned drive components.

Check that all mounting bolts are tight. Replace defective

parts as required.

With proper combustion adjustment the heating element of a

gas fired furnace will seldom need cleaning. If the element

should become sooted, it can be cleaned as follows:

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1. Remove the burner assembly as outlined in BURNER

INSTRUCTIONS.

2. Remove the roof over the gas heat section.

3. At the top plate from the top draft blower housing and the

top draft blower wheel.

4. Remove the screws holding the top of the flue collector

box. Carefully remove the top of the flue collector box

without ripping the adjacent insulation. Then remove the

center divider plate separating the upper and lower flue

boxes.

5. On the inside of the flue collector box, remove the flue

baffles from the tube interiors. Note the last bend of the

baffle fits tightly against the tube forcing the end of the

baffle to lock into the tube collar. This collar is formed

when the tube is expanded into the end sheet. To

FIGURE 21 : TYPICAL FLUE BAFFLE INSTALLA-

TION

TROUBLESHOOTING

remove, move the end of the baffle toward the center of

the tube releasing the end of the baffle from the tube col-

lar, then pull straight out of the tube. Refer to Figure 20.

6. Using a wire brush on a flexible wand, brush out the

inside of each heat exchanger from the burner inlet and

flue outlet ends.

Label all wires prior to disconnection when servic-

ing controls. Wiring errors can cause improper and

dangerous operation. Verify proper operation after

servicing.

7. Brush out the inside of the flue collector box and the flue

baffles.

8. Run the wire brush down the vent hoods from the flue

collector end.

9. If soot build-up is particularly bad, remove the vent motor

and clean the wheel and housings. Run the wire brush

down the flue extensions at the outlet of the vent hous-

ings.

Troubleshooting of components necessarily

requires opening the electrical control box with the

power connected to the unit. Use extreme care

when working with live circuits! Check the unit

nameplate for the correct line voltage and set the

volt meter to the correct range before making any

connections with line terminals.

10. After brushing is complete, blow all brushed areas with

air or nitrogen. Vacuum as needed.

11. Replace parts in the order they were removed in Steps 1

through 4.

Prior to any of the following maintenance proce-

dures, shut off all electric power to the unit to pre-

vent personal injury.

12. When replacing the center and top of the flue collector

box, be careful not to tear the adjoining insulation.

NOTE: To find the Btu input, multiply the number of cubic feet

of gas consumed per hour by the Btu content of the gas in

your particular locality (contact your gas company for this

information - it varies widely from city to city.)

13. Ensure that all seams on the vent side of the combustion

system are air tight. Apply a high temperature (+500°F)

sealing compound where needed.

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035-17233-000-C-0702

1. The indoor blower motor is a non-inherently protected

three-phase motor. Protection is provided by an overload

relay for overcurrent and fuses for short circuit. If the

motor fails to run, check the line voltage circuit and con-

trol voltage circuit per the following procedure:

has ignited with the fan switch in the AUTO position,

check for loose 24 volt wiring between the relay

board in the main control box, the Mate-N-Lok con-

nector in the partition between the evaporator and

gas heat sections and the time delay relay (ETD).

a. If the Indoor Blower Motor does not operate, check

visually that contactor M3 is pulled in. If so, check

for line voltage between all three phases at the line

terminals of the Blower Overload Relay (BOR). If

line voltage is found, check the leads to the blower

motor for open circuit. If line voltage is found at the

motor leads (inside the conduit box on the motor

shell), disconnect the motor and check for open

windings per the motor wiring diagram. If open wind-

ings are found, replace the motor. If line voltage is

not found at the BOR, trace the leads back to the

field supply terminal block, checking for an open cir-

cuit or blown fuses.

g. If all control wiring is fine, check for 24 volts at the

relay board. If 24 volts is present, replace the relay

board. If 24 volts is not present, replace the (ETD)

relay.

NOTE: The furnace may shut itself down on a high tempera-

ture condition during the procedure, but this will not effect the

test if it is done within 5 minutes of furnace shut-down.

3. The supply air blower operates but the draft motor does

not when the room thermostat is set to call for heat and

the fan switch in the ON position.

a. The draft motor has inherent protection. If the motor

shell is hot to the touch, wait for the internal over-

load to reset.

b. If the contactor M3 is not pulled in, check for control

voltage (24V) at the M3 coil. If voltage is found,

replace the contactor. If control voltage is not found

at M3, check for voltage across terminals 95 & 96 of

the BOR. If voltage exists, the BOR is open on over-

load. The BOR should be set to the auto reset posi-

tion. The BOR must cool down in order to reset. If

the BOR will not reset, replace the BOR. If the BOR

resets and M3 pulls in, but the indoor blower motor

will still not run, refer to para. (a) for troubleshooting

the line voltage supply circuit. If control voltage is

not found at the BOR, trace the circuit back to the

relay board and thermostat per the unit wiring dia-

gram. Replace any defective components.

b. If the motor shell is cold with the room thermostat

calling for heat, check for line voltage at the motor's

Mate-N-Lok connector attached to the evaporator

partition. If line voltage is present, replace the draft

motor.

c. If line voltage is not present, check for line voltage at

the heat relay (RW1) contacts in the main control

box and check to see if the (RW1) is pulled in.

d. If the (RW1) relay is pulled in, check for a loose line

voltage connection.

e. If the (RW1) relay is not pulled in, check for 24 volts

at the (RW1) coil. If 24 volts is present, replace the

(RW1) relay. If 24 volts is not present, check for a

loose 24 volt connection back to the relay board and

check the connections from the room thermostat to

the relay board. If all connections are correct,

replace the relay board.

2. Draft motor operates and furnace lights but supply air

blower does not start after a short time delay with room

thermostat fan switch set to AUTO.

a. Set fan switch to ON. If blower motor runs, go to

Step f. If it does not, check to see if line voltage is

being supplied to the contacts of the contactor (M3),

and if the contactor is pulled in. Check for loose wir-

ing.

4. The draft motor runs but the furnace does not light and

the sparker does not spark.

b. If contactor (M3) is pulled in, proceed with the trou-

bleshooting steps indicated in Step 1 above.

a. The ignition control (IC1, IC2) may be locked out

due to either a flame roll out or 100% shut off. These

safety features are described above. If lock-out has

occurred, 24V must be removed from the ignition

controls. This is done at the unit or by resetting the

room thermostat. After resetting 24V, check for

proper furnace operation. If lock-out continues to

occur, locate the source of the problem and correct.

c. If (M3) is pulled in and the blower motor still does

not run, replace the blower motor.

d. If (M3) is not pulled in, check for 24 volts at the (M3)

coil. If 24 volts is present, replace the (M3) contac-

tor.

e. If 24 volts is not present at the (M3) coil, check for

loose 24 volt wiring back to the relay board. Check

control wiring to the room thermostat. If all is fine,

replace the relay board.

b. Check all 24 volt connections from the relay board

to and in the gas heat section. Check low voltage

connections to the (ETD) located in the control box.

c. If the furnace is hot, it may be out on an over-tem-

perature condition, wait for limit reset.

f. If the blower motor runs with the fan switch in the

ON position but does not run soon after the furnace

Unitary Products

d. If the furnace is cold, check for 24 volts at wire 241

attached to the time delay relay (ETD) located in the

main control box. If 24 volts is not found, replace the

ETD relay.

6. The sparker sparks at the pilot burner but the pilot does

not ignite and a gas odor is detected at the draft motor

outlet.

a. Adjust the pilot adjust screw on the gas valve as

described in PILOT CHECKOUT.

e. If 24 volts is found at wire 241, remove the wires

attached to the (ETD) and with a VOM, check for

continuity across contacts 1 and 2. If none is found,

the (ETD) is open and must be replaced. If there is

continuity, re-attach the wires.With the draft motor

running, check for 24 volts at terminal 4 of (RW1-2)

and (RW2-1). If 24 volts is not present, the centrifu-

gal switch (CS) has not closed or has gone bad.

Check the line voltage to the unit - if it is correct,

replace the draft motor. If line voltage is low, call the

power company.

b. Check the supply pressure as described in POST

START CHECK LIST. Make adjustments as neces-

sary.

c. Check the pilot orifice for obstruction as described in

para. 5d. Clean as needed but the problem should

not be the gas valve.

7. The pilot burner ignites but the sparker continues to

spark and the main burners do not ignite.

a. Make the same checks and adjustment as

described in para. 6.

f. Check for 24V at terminal 2 of (RW1-2 and RW2-1).

If 24V is not present, check for 24V at (RW1 and

RW2) relay coils. If these relays are pulled in, then

check for a loose connection at terminal 2 and termi-

nal 4 of each relay. If no problem is found, then

replace (RW1 and/or RW2) as required.

b. Make sure that the pilot burner is not bent or dam-

aged.

c. Make sure that the ground connections at the pilot

burner, gas valve and ignitor control are intact.

Check the high tension wire for good electrical con-

nection. If all are intact, replace the ignitor module.

g. If 24 volts is present at the ignitor controls, check all

control wiring at the ignitor controls and the high ten-

sion wire to the ignitors. Check that the ground wires

from the ignitor controls, the gas valves and pilot

burners are all intact and making good electrical

connection. Check to make sure that the ceramic

insulator on the pilot ignitors or sensors is not bro-

ken or cracked, if all are intact, replace the ignition

control IC1 or IC2.

8. The pilot burner lights and the spark stops but the main

burners do not light.

a. Check electrical connections between the ignitor

control and the gas valve. If intact, check for 24 volts

across terminals MV and COMMON terminals. If no

voltage detected, replace ignitor control. If voltage is

present, replace gas valve.

5. The draft motor runs and the sparker sparks at the pilot

burner but the pilot does not ignite and a gas odor is not

detected at the draft motor outlet.

9. Furnace lights with roll-out or one burner has delayed

ignition.

a. Check to make sure gas is being supplied to the

unit. Make sure that the gas pressure to the unit is

within the proper limits as described in the POST

START CHECK LIST and that the pilot adjust screw

is allowing some flow of gas as described in PILOT

CHECKOUT.

a. Make sure that the pilot burner is aligned properly

with the carryover as described in PILOT CHECK-

OUT.

b. Make sure that the carry overs on adjoining burners

are screwed fast and are level with respect to one

another.

b. Check all wiring between the ignitor control and the

gas valve. Check to make sure the ground connec-

tions are intact.

10. Main burners light but exhibit erratic flame characteris-

tics.

c. If the wiring is intact, check for 24 volts across termi-

nals PV and COMMON on the ignitor control. If 24

volts is not present, replace the ignitor control.

a. Adjust air shutters as described in BURNER AIR

SHUTTER ADJUSTMENT.

b. Check the main burner orifices for obstruction and

alignment. Removal procedure is described in

BURNER INSTRUCTIONS. Clean or replace burner

orifices and burners as needed.

d. If 24 volts is present, remove the pilot burner and

remove the pilot orifice from the pilot burner. The ori-

fice is removed in the direction opposite the flow of

gas. Inspect the orifice for obstruction. If it is clear,

replace the main gas valve.

Subject to change without notice. Printed in U.S.A.

Supersedes: 035-17233-000 Rev B (0500)

035-17233-000-C-0702

Unitary

Products

Group

5005

York

Drive

Norman

73069

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