Greenheck Fan Make Up Air Unit VSU User Manual

Part #457831

VSU Make-Up Air Unit

Installation, Operation and Maintenance Manual

Please read and save these instructions. Read carefully before attempting to assemble, install, operate or maintain the

product described. Protect yourself and others by observing all safety information. Failure to comply with instructions

could result in personal injury and/or property damage! Retain instructions for future reference.

2. The rotation of the wheel is critical. It must be

Model VSU

free to rotate without striking or rubbing any

stationary objects.

3. Motor must be securely and adequately

grounded.

4. Do not spin fan wheel faster than the maximum

cataloged fan rpm. Adjustments to fan speed

signiﬁcantly affects motor load. If the fan RPM is

changed, the motor current should be checked

to make sure it is not exceeding the motor

nameplate amps.

5. Do not allow the power cable to kink or come

in contact with oil, grease, hot surfaces,

or chemicals. Replace cord immediately if

damaged.

6. Verify that the power source is compatible with

Optional Service

Platform Shown

the equipment.

7. Never open blower access doors while the fan is

running.

General Safety Information

FOR YOUR SAFETY

Only qualiﬁed personnel should install this unit.

Personnel should have a clear understanding of these

instructions and should be aware of general safety

precautions. Improper installation can result in electric

shock, possible injury due to coming in contact with

moving parts, as well as other potential hazards.

Other considerations may be required if high winds

or seismic activity are present. If more information

is needed, contact a licensed professional engineer

before moving forward.

If you smell gas:

1. Open windows.

2. Do not touch electrical switches.

3. Extinguish any open flame.

4. Immediately call your gas supplier.

FOR YOUR SAFETY

The use and storage of gasoline or

other flammable vapors and liquids in

open containers in the vicinity of this

appliance is hazardous.

1. Follow all local electrical and safety codes, as

well as the National Electrical Code (NEC), the

National Fire Protection Agency (NFPA), where

applicable. Follow the Canadian Electric Code

(CEC) in Canada.

WARNING

DANGER

Improper installation, adjustment,

alteration, service or maintenance can

cause property damage, injury or death.

Read the installation, operating and

maintenance instructions thoroughly

before installing or servicing this

equipment.

Always disconnect power before working on or

near a unit. Lock and tag the disconnect switch or

breaker to prevent accidental power up.

CAUTION

When servicing the unit, motor may be hot enough

to cause pain or injury. Allow motor to cool before

servicing.

Model VSU Make-Up Air Unit

Table of Contents

Installation

1. Filter/Stand Section

Filter/Stand Section . . . . . . . . . . . . . . . . . . . . . .3-4

Burner/Blower Section . . . . . . . . . . . . . . . . . . . . . 4

Ductwork . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Dimensional Data . . . . . . . . . . . . . . . . . . . . . . . . . 5

Direct Gas Piping . . . . . . . . . . . . . . . . . . . . . . . .6-7

Start-Up

The unit should be mounted on a concrete slab four

inches thick with a proper gravel drainage bed. Allow

one foot on each side of the unit as shown in the

Concrete Slab and Unit Footprint drawing below.

Concrete Slab Dimensions

Blower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-9

Direct Gas . . . . . . . . . . . . . . . . . . . . . . . . . . . .10-12

Operation

Electrical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Troubleshooting

Blower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Heater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15-17

Maintenance

Housing Size

135

111

All dimensions are shown in inches.

Routine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18-19

Fall . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Reference

Building Wall

Approx. Stand Feet Locations

Typical Control Center Layout . . . . . . . . . . . . . . 20

Typical Gas Train Layout. . . . . . . . . . . . . . . . . . . 20

Start-Up Check List . . . . . . . . . . . . . . . . . . . . . . 21

Maintenance Log . . . . . . . . . . . . . . . . . . . . . .22-23

Warranty . . . . . . . . . . . . . . . . . . . . . . . . .Backcover

Concrete Slab

Concrete Slab and Unit Footprint

The ﬁlter section ships inside the stand (see drawing

on next page). After the unit is set on the slab, it can

be anchored through the stand feet. The unit footprint

of the unit is shown above.

Greenheck recommends having a three foot clearance

on the controls side and a two foot clearance on the

other three sides of the unit for serviceability.

The following statement pertains to direct gas units

only. When ordered with insulation, this unit has a

zero-inch clearance tolerance to any combustibles,

on all sides and top. Without insulation, the clearance

tolerance is six inches.

Model VSU Make-Up Air

4. Complete Installation

A typical horizontal discharge installation is shown.

Gas and/or electrical lines can be connected at this

time.

Installation continued

2. Burner/Blower Section

Use a crane and a spreader bar hooked to the factory

lifting lugs (shown below) to lift and center the unit

onto the ﬁlter stand section. The sections can be

caulked together, but it is not needed with the water

kickouts provided with this section.

For upblast units, a duct elbow may be needed to

turn the ductwork into the building. Follow proper

ductwork methods recommended by AMCA to make

this elbow to minimize duct losses.

3. Install Ductwork

This table shows the duct sizes and straight lengths

recommended for optimal performance (AMCA

Publication 201-90). Using duct sizes less than

recommended will affect fan performance. Good

duct installation practices should be followed for

the remaining ductwork. See the drawings in the

Dimensional Data section for duct locations.

Recommended Supply Ductwork Sizes

VSU

Blower Size

Duct

Size

Straight Duct

Length

220

68 x 26 inches

117 inches

Model VSU Make-Up Air

Dimensional Data

Upblast Discharge

Elevation View

Lifting Lugs

Electrical Controls

Gas Controls*

24^

*Direct Gas units only

^Standard factory clearance. Additional stand heights are available from the factory.

Unit Dimensional Data

Blower Dimensional Data

Unit Weight

Housing

Size

Blower

Size

Filters

Blower/Heater*

Stand/Filter

111

144

(20) 20x25

220

2000 lbs.

700 lbs.

All dimensions are shown in inches.

* Weights will vary with blower and horsepower.

Model VSU Make-Up Air

1. Determine the Supply Gas

Requirements

Installation of Direct Gas Piping

The unit’s direct gas nameplate states the requirements

for the gas being supplied to the unit. The direct gas

nameplate is located on the outside of the unit on the

control center side.

Minimum gas pressure for

maximum output

IMPORTANT

All gas piping must be installed in accordance

with the latest edition of the National Fuel Gas

Code ANSI/Z223.1 and any local codes that may

apply. In Canada, the equipment shall be installed

in accordance with the Installation Code for Gas

Burning Appliances and Equipment (CGA B149)

and Provincial Regulations for the class. Authorities

having jurisdiction should be consulted before

installations are made.

MAX BTU/HR

BTU/H MAX

MIN BTU/HR

BTU/H MIN

NORMAL MANIFOLD

PRESSURE

PRESSION DÕADMISSION

NORMALE

MIN GAS PRESSURE

FOR MAX OUTPUT

PRESSION DE GAZ MIN

POUR PUISSANCE MAX

“ W.C.

WARNING

MIN GAS

PRESSURE

PRESSION DE GAZ

MAX GAS

PRESSURE

PRESSION DE GAZ

MAX

All components of this or any other gas-fired heating

unit must be leak tested prior to placing the unit

into operation. A soap and water solution should be

used to perform this test. NEVER test for gas leaks

with an open flame.

MIN BURNER

MAX BURNER

PRESSURE DROP

PERTE MIN DE PRESSION

DANS LE BRULEUR

PRESSURE DROP

PERTE MAX DE PRESSION

DANS LE BRULEUR

PSI

TYPE OF GAS

NATURE DU GAZ

DESIGN ∆T

∆T NORMALE

WARNING

EQUIPPED FOR

CONCU POUR

AGAINST

CONTE

EXTERNAL STATIC PRESSURE

SCFM

“ W.C.

If pressure testing in excess of 1/2 psig (3.5 kPa),

the heater and manual shutoff valve must be

disconnected from the supply gas line.

PRESSION STATIQUE EXTERIEURE

Type of gas

Maximum gas pressure

WARNING

Direct Gas Nameplate

If pressure testing at or below 1/2 psig (3.5 kPa), the

heater must be isolated from the supply gas line by

closing its manual shutoff valve.

2. Install Additional Regulator if Required

When the supply gas pressure exceeds the maximum

gas pressure shown on the direct gas nameplate, an

additional regulator (by others) is required to reduce

the pressure. The regulator must have a listed leak

limiting device or it must be vented to the outdoors.

IMPORTANT

All piping should be clean and free of any foreign

matter. Foreign material entering the gas train can

damage the valves, regulators and burner.

IMPORTANT

NOTE

Do NOT connect the unit to gas types other than

what is specified and do NOT connect the unit to

gas pressures that are outside of the pressure range

shown on the label.

The regulator located inside the unit is used to

adjust the unit’s maximum output temperature.

3. Connect the Supply Gas Line

NOTE

A manual shut off valve (gas cock), 1/8 in. plugged

test port and 6 in. drip leg must be installed prior to

the gas train. The valve and the test port must be

accessible for the connection of a test gauge. Supply

gas connections must be made by a qualiﬁed installer

and are not furnished by Greenheck.

When connecting the gas supply, the length of the

run must be considered in determining the pipe size

to avoid excessive pressure drop. Refer to a Gas

Engineer’s Handbook for gas pipe capacities.

Controls

Gas Cock

Ground Joint Union

From

Gas

Supply

1/8 in. Plugged Ta p

6 in. Trap

Supply Gas Line

Model VSU Make-Up Air

4. Pipe the Optional Vent Line

If an optional vent line is located between the safety

shutoff valves it must be piped to the outdoors.

WARNING

Reference the National Fuel Gas Code for additional

vent line requirements.

Vent Line Solenoid

To Outdoors

To Burner

From Supply

Safety

Shut-off Valves

Optional Vent Line

5. Test the System for Leaks

Check both the supply lines and the factory piping for

leaks. Apply a soap and water solution to all piping

and watch for bubbling which indicates a leak.

WARNING

NEVER test for a gas leak with an open flame.

NOTE

The factory piping has been checked for leaks, but

should be rechecked due to shipping and installation.

Model VSU Make-Up Air

2. Check the Blower Rotation

Open the blower access door

and run the blower momentarily

to determine the rotation.

Start-Up - Blower

Refer to the Start-Up Checklist in the Reference

section before proceeding further!

Arrows are placed on the

Pre Start-Up Check

blower scroll to indicate the

proper direction or reference

the example shown to the right.

Rotate the fan wheel by hand and make sure no parts

are rubbing. Check the V-belt drive for proper alignment

and tension (a guide for proper belt tension and

alignment is provided in the Belt Maintenance section).

Check fasteners, set screws and locking collars on the

fan, bearings, drive, motor base, and accessories for

tightness.

Blower

Housing

Blower Rotation

NOTE

To reverse the rotation on three phase units,

disconnect and lock-out the power, then

interchange any two power leads.

WARNING

Disconnect and lock-out all power and gas before

performing any maintenance or service to the unit.

Failure to due so could result in serious injury or

death and damage to equipment.

NOTE

To reverse the rotation on single phase units,

disconnect and lock-out the power, then rewire the

motor per the manufacturer’s instructions.

IMPORTANT

SPECIAL EQUIPMENT REQUIRED

If the blower is rotating in the wrong direction, the

unit will move some air, but will not perform as

designed. Be sure to perform a visual inspection to

guarantee the correct blower rotation.

Required and recommended tools. Equivalent

products may be used.

Manufacturer:

Model:

Phone:

Fluke

177

1-800-44-FLUKE

Voltage &

Amperage

Meter

3. Check for Vibration

www.fluke.com

Check for unusual noise, vibration or overheating of

the bearings. Reference the Troubleshooting section

for corrective actions.

Manufacturer:

Model:

Phone:

Fluke

1-800-44-FLUKE

Thermometer

IMPORTANT

www.fluke.com

Manufacturer:

Model:

Fluke

116

1-800-44-FLUKE

Excessive vibration may be experienced during

the initial start-up. Left unchecked, it can cause a

multitude of problems including structural and/or

component failure.

Micro Amp

Meter

Phone:

www.fluke.com

Manufacturer:

Model:

Dwyer

Slack Tube

1-219-897-8000

IMPORTANT

U-Tube

Manometer

Phone:

Generally, fan vibration and noise is transmitted

to other parts of the building by the ductwork. To

minimize this undesirable effect, the use of heavy

canvas duct connectors is recommended.

www.dwyer-inst.com

Manufacturer: Monarch

Model:

Phone:

Pocket Tach 100

1-800-999-3390

Tachometer

www.monarchinstrument.com

4. Motor Check

Measure the motor’s voltage, amps and RPM.

Compare to the speciﬁcations. Motor amps can be

reduced by lowering the motor RPM or increasing

system static pressure.

WARNING

Check the housing, blower, and ductwork for any

foreign objects before running the blower.

1. Check the Voltage

Before starting the unit, compare the supplied voltage,

hertz, and phase with the unit and motor’s nameplate

information.

Voltage, Hertz, Phase

VOLTS

EXH HP

MOP

SUP HP

MCA

Electrical Nameplate

Model VSU Make-Up Air

5. Air Volume Measurement & Check

Measure the unit’s air volume (cfm) and compare it with

it’s rated air volume. If the measured air volume is off,

adjust the fan’s RPM by changing/adjusting the drive.

NOTE

The most accurate way to measure the air volume is

by using a pitot traverse method downstream of the

blower. Other methods can be used, but should be

proven and accurate.

IMPORTANT

Changing the air volume can significantly increase

the motor’s amps. If the air volume is changed,

the motor’s amps must be checked to prevent

overloading the motor.

NOTE

To ensure accuracy, the dampers are to be open

when measuring the air volume.

6. Set-up Optional Components

Adjust the settings on the optional components. See

the Control Center Layout in the Reference section for

location of optional components.

• Heating Inlet Air Sensor

Typical setting: 60-70ºF

Model VSU Make-Up Air

3. Set the Burner Air Pressure Differential

With the fan running and discharging 70ºF (21ºC) air,

connect a U-Tube manometer to the outer sensing

probes (see below) and measure the static pressure

across the burner.

Start-Up Direct Gas

IMPORTANT

For proper unit function and safety, follow the start-

up procedure in the exact order that it is presented.

Outer Sensing Probes

IMPORTANT

This start-up should begin after all of the installation

procedures and the blower start-up have been

completed.

0.625 - 0.675 in. wc

1. Check the Supply Gas Pressure

Check the supply gas pressure and compare it with

the unit’s nameplate pressure requirements. Adjust

the supply regulator as needed until the supply gas

pressure is within the speciﬁed range. The direct gas

nameplate is located on the outside of the unit on the

control center side.

U-Tube

Manometer

Measuring the Pressure Drop

Minimum and maximum gas

pressures for maximum output

The proper static pressure should be between 0.625

and 0.675 inches wc (155.68 and 168.64 Pa). If

needed, evenly adjust the bafﬂes on both sides of the

burner, keeping the burner centered in the opening

until the required pressure is obtained.

MAX BTU/HR

BTU/H MAX

MIN BTU/HR

BTU/H MIN

NORMAL MANIFOLD

PRESSURE

PRESSION DÕADMISSION

NORMALE

MIN GAS PRESSURE

FOR MAX OUTPUT

PRESSION DE GAZ MIN

POUR PUISSANCE MAX

“ W.C.

MIN GAS

PRESSURE

PRESSION DE GAZ

MAX GAS

PRESSURE

PRESSION DE GAZ

MAX

Burner

MIN BURNER

MAX BURNER

PRESSURE DROP

PERTE MIN DE PRESSION

DANS LE BRULEUR

PRESSURE DROP

PERTE MAX DE PRESSION

DANS LE BRULEUR

PSI

Adjustable

Bafﬂe

Adjustable

Bafﬂe

TYPE OF GAS

NATURE DU GAZ

DESIGN ∆T

∆T NORMALE

Airﬂow

EQUIPPED FOR

CONCU POUR

AGAINST

CONTE

EXTERNAL STATIC PRESSURE

“ W.C.

SCFM

PRESSION STATIQUE EXTERIEURE

Type of gas

Burner and Bafﬂes

Direct Gas Nameplate

NOTE

2. Check the Pilot Gas Pressure

The pressure drop was set at the factory and may

not need adjustment.

Check the pilot gas pressure. The recommended

gas pressure is 3 in. wc. Adjust the pilot regulator as

needed. See the Gas Train Layout in the Reference

section for the location of the pilot pressure test port

and pilot regulator.

NOTE

When required pressure is obtained, be sure to

reconnect the outer sensing probes.

IMPORTANT

This process may need to be repeated until the

proper pressure is achieved. This adjustment

will change the air quantity delivered by the unit

and therefore the air quantity delivered should be

rechecked. Refer to the Blower Start-Up section.

Proper air velocity over the burner is critical on direct

fired gas units. If the air velocity is not within the unit

specifications, the unit will not operate efficiently,

may have sporadic shutdowns, and may produce

excessive carbon monoxide (CO) or other gases.

NOTE

To increase the static pressure decrease the

opening. To decrease the static pressure increase

the opening.

Model VSU Make-Up Air

4. Set the Maximum Firing Rate

Monitor the unit’s actual temperature rise by placing

a thermocouple in the unit’s inlet and a second in the

discharge, three duct diameters downstream of the

burner.

Regulators and Modulating Valves

Remove one wire to

Remove cap to access

maximum firing rate

adjustment

send the unit to the

minimum firing rate

Send the unit to maximum ﬁre by disconnecting and

isolating the wire connected to Terminal 4 on the

Maxitrol 14.

While monitoring the units temperature rise, set the

maximum ﬁring rate by adjusting the regulator until the

designed temperature rise is achieved. After setting the

maximum ﬁring rate, reconnect the wire to the ampliﬁer.

Minimum

firing rate

adjustment

NOTE

Separate Regulator and Modulating Valves

Do not set the burner maximum firing rate based on gas

pressure. It should be set based on the unit’s designed

temperature rise shown on the direct gas label.

5. Set the Minimum Firing Rate

Disconnect and isolate one of the wires running to

the modulating valve to send the unit to its minimum

ﬁring rate. Set the minimum ﬁring rate by adjusting the

needle valve shown above.

MIN GAS

MAX GAS

PRESSURE

PRESSION DE GAZ

PRESSURE

PRESSION DE GAZ

MAX

“ W.C.

After setting the minimum ﬁring rate, shut off the

pilot to ensure that the ﬂame safeguard can still read

the main ﬂame signal. Reconnect the wire to the

modulation valve and open the pilot shut-off valve.

MIN BURNER

MAX BURNER

PRESSURE DROP

PERTE MIN DE PRESSION

DANS LE BRULEUR

PRESSURE DROP

PERTE MAX DE PRESSION

DANS LE BRULEUR

PSI

TYPE OF GAS

NATURE DU GAZ

DESIGN ∆T

∆T NORMALE

EQUIPPED FOR

CONCU POUR

AGAINST

CONTE

EXTERNAL STATIC PRESSURE

NOTE

“ W.C.

SCFM

PRESSION STATIQUE EXTERIEURE

The minimum setting for the maximum firing rate

may be higher than required. This is acceptable. The

burner will modulate as needed.

Direct Gas Nameplate

IMPORTANT

Maxitrol Series 14 — 7 terminals

The proper minimum firing rate setting results in a

small ribbon of continuous flame which covers the

flame road and runs across the entire burner.

Remove the wire from terminal #4 to

send the unit to maximum fire

IMPORTANT

Do not allow the disconnected wire to come in

contact with a potential ground. Damage to the

amplifier or transformer could result.

NOTE

Gas trains are equipped with separate regulators

and modulating valves.

Low fire time delay setting (75% of maximum)

NOTE

IMPORTANT

Adjusting the maximum and minimum firing rate

requires the inlet air sensor to be set higher than the

outdoor air temperature in order to start the burner(s).

Once high and low fire have been set, the inlet air

sensor should be set to the desired temperature.

Setting the maximum firing rate during mild weather

conditions may cause the high limit to trip out during

extreme conditions requiring manual resetting.

NOTE

Gas trains are equipped with either separate

regulators and modulating valves or with a

combined modulating valve.

Counterclockwise rotation increases the minimum

fire rate setting, clockwise rotation decreases the

setting.

NOTE

Clockwise rotation increases the temperature

rise, counterclockwise rotation decreases the

temperature rise.

Model VSU Make-Up Air

6. Set the Unit’s Operating Temperature

Set the operating temperature. The operating

temperature setting depends on which Maxitrol controller

is used.

Maxitrol Series 14

The Maxitrol Series 14 should be set to the desired

discharge temperature. The temperature selector is built

into the amplifier.

Set the discharge temperature

Typical: 65ºF

Series 14 Discharge Temperature Setting

7. Flame Signal Check

To measure the ﬂame signal connect a standard DC

voltmeter to the ﬂame ampliﬁer test jacks + and -

(com) as shown to

the right. The ﬂame

signal should be

above 1.25 VDC and

steady.

Check the ﬂame

signal with the

burner at pilot only,

minimum ﬁre, mid

ﬁre and high ﬁre.

DC Voltmeter and

Flame Ampliﬁer

IMPORTANT

If the flame signal is not above 1.25 VDC and steady,

consult the troubleshooting section.

Model VSU Make-Up Air

Operation - Electrical

Electrical Sequence

Direct Gas Burner Sequence

1. Supply Fan Contact (S2) Closed

1. Supply Fan Contact Closed

• Power passes to damper which opens

• Power passes to the supply fan and heat switch

• When damper is fully opened, damper relay

(D1) is energized an optional N.O. damper limit

switch (DL1) closes

2. Heat Contact Closed

• Power passes to the heat relay then to the

Flame Safeguard

• Power passes through a N.C. fault contact on

soft starter (PST(FAULT))

• Power passes to and energizes supply fan relay

(RI)

3. Flame Safeguard (FSG) Sequence

• Checks for proper airﬂow

• Veriﬁes no ﬂame present at burner

• Initiates 10 second prepurge

• Sends power to open pilot gas valve (V1) and

energizes the spark generator (SG) (clicking of

the spark generator may be heard)

• Tries for up to 10 seconds to light pilot and

conﬁrm ﬂame

• Powers the main gas valves open

• Shuts down spark generator

• Continuously monitors the ﬂame and airﬂow

• Supply fan starts

2. Heat Contact (S4) Closed

• Power passes to N.O. fan relay which is

energized and closed

• Power passes to inlet air sensor contact (TS)

which is energized and closed if the inlet air

temperature is below the set point

• Power passes to and energizes the heat relay

(RH)

• N.O. heat relay contact (RH) closes

• Power passes to and energizes terminal 5 of the

• Performs self-diagnostic check every ﬁve

seconds

Flame Safeguard (FSG).

• Power passes to N.C. high limit control contact

(HLC) which is closed if temperature has

remained below the high limit set point

• Power passes to terminal 6 of the Flame

Safeguard (FSG)

• Flame Safeguard (FSG) begins direct gas burner

sequence (see Direct Gas Burner sequence)

Model VSU Make-Up Air

Troubleshooting

Blower Does Not Operate

115 VAC between

Check Main Voltage

(See Blower Start-Up Step #1)

Main Disconnect (DS1) Off

(Turn Main Disconnect DS1 On)

Primary Fuses Blown

terminals 102 and 101?

Yes

(Replace Fuses)

Main Transformer Defective

(Replace Transformer)

24 VAC between

terminals R and X?

Main Transformer Defective

Yes

(Replace Transformer)

24 VAC between

terminals G and X?

Supply Switch (S2) Off

(Turn Supply Switch (S2) On)

Yes

24 VAC between

terminals 7 and X?

Yes

Damper Limit Switch (DL1) Holding

(Wait for actuator to open fully or adjust limit switch)

Broken Fan Belt

(Replace - Reference Maintenance section)

Defective motor or capacitor

(Repair/Replace)

Blown Motor Fuse

(Replace)

One or more legs of 3 phase is out

(Restore missing legs)

At this time the supply should be energized., passing

power to the supply motor and the blower should start.

Model VSU Make-Up Air

Troubleshooting

Heater Does Not Operate

Does not attempt to light (No visible spark)

24 VAC between

terminals W1 and X?

Heat Switch (S4) Off

(Turn Heat Switch (S4) On)

Heat Switch Not Wired

(Wire Heat Switch (S4))

Yes

115 VAC between

terminals 102 and 101?

Primary Fuses Blown

(Replace Fuses)

Main Transformer (TR4) Defective

(Replace Transformer)

Yes

115 VAC between

terminals 103 and 101?

Inlet Air Sensor (TS) Holding

(Adjust TS setting — Reference Blower Start-Up Step #6)

Heat Relay (RH) Defective

Yes

(Replace Heat Relay (RH))

The power light on the flame safeguard should

blink approximately every 5 seconds as it

performs a self-diagnostics check.

115 VAC between

terminals 104 and 101?

High Limit (HLC) Tripped

(Reset/Replace High Limit (HLC))

(Check on cause of control loss)

Yes

Continuity between

terminals 107 and 108?

Airflow Switch (PS) Holding for Proper Airflow

(Correct airflow across burner)

Yes

(Reference Direct Gas Start-Up Step #3)

At this time the heater should attempt to light.

(The pilot light on the flame safeguard should illuminate).

Model VSU Make-Up Air

Troubleshooting

Heater Does Not Operate

Attempts to light, but no pilot (visible spark)

Check inlet gas pressure.

Note: The minimum and maximum gas pressures

for your unit are shown on the direct gas label.

(Reference Direct Gas Start-Up – Step #1)

(Direct Gas Start-Up Step #1)

Yes

Gas pressure between the

minimum and maximum shown

on the direct gas label?

Correct gas pressure

(Reference Direct Gas Start-Up – Step #1)

Yes

Air in the gas line?

Purge gas line

(Verify gas at the pilot)

Check for proper airﬂow

(Direct Gas Start-Up Step #3)

Note: The airflow may satisfy the airflow switch,

but may make lighting the pilot difficult. Adjust the

pressure drop across the burner between 0.625 and

0.675 in. wc shown in Direct Gas Start-Up – Step #3

Yes

Pressure drop across the burner

between 0.625 and 0.675 in. wc?

Adjust burner baffles

(Reference Direct Gas Start-Up – Step #3)

Yes

Crossed flame and spark wires

(Uncross wires and reconnect)

Incorrect spark plug gap

(Set spark plug gap to 0.062 in.)

Defective spark plug

Proper spark?

Yes

(Replace spark plug)

Check for proper pilot pressure

(Direct Gas Start-Up Step #2)

Note: A high pilot pressure will make lighting more

difficult. Lower the pilot pressure in increments

until the unit lights. Then set the pilot per the

instruction in Direct Gas Start-Up – Step. #2

Pilot pressure correct?

Adjust the pilot pressure

(Reference Direct Gas Start-Up – Step #2)

Yes

With proper airflow, gas pressure and spark,

the unit should light.

If problems remain, consult the factory

Model VSU Make-Up Air

Troubleshooting

Heater Does Not Operate

Visible pilot

Measure the ﬂame signal

when there is a visible pilot

Note: The flame signal should be steady and

above 1.25 VDC with a visible pilot.

(Reference Direct Gas Start-Up – Step #7)

Flame signal greater

than 1.25 VDC

Unit is not grounded

(Properly ground unit)

Flame rod is grounding out

(Adjust the flame rod to avoid contact with the burner or the unit)

Cracked porcelain on flame rod

(Replace flame rod)

Yes

Check for proper airﬂow

(Direct Gas Start-Up Step #3)

Note: When the pressure is low or marginal and the unit

begins heating, the air density will change. This can cause

the pressure to drop below the minimum setting. Also, low

airflow can cause the flame to walk out of the burner and

away from the flame sensor, causing the unit to recycle.

Pressure drop across the burner

between 0.625 and 0.675 in. wc?

Adjust burner baffles

(Reference Direct Gas Start-Up – Step #3)

Yes

Check the minimum ﬁring rate

(Direct Gas Start-Up Step #4

Is the minimum ﬁring rate

set correctly?

Adjust the minimum firing rate

(Reference Direct Gas Start-Up – Step #4)

Yes

Does the ﬂame signal

remain constant?

If the signal slowly drops off, typically the airflow is too low

(Reference Blower Start-Up – Step #4)

If it suddenly drops to zero, the flame rod is grounding out

(Adjust the flame rod to avoid contact with the burner or the unit)

Yes

If the flame signal is above 1.25 VDC and constant,

the main gas valves will remain open until the call

for heat is interrupted or the unit is shut down.

Model VSU Make-Up Air

Maintenance - Routine

Motors

CAUTION

Motor maintenance is generally limited to cleaning

and lubrication (where applicable).

Cleaning should be limited to exterior surfaces only.

Removing dust and grease build-up on the motor

assures proper motor cooling.

Motors supplied with grease ﬁttings should be

greased in accordance with the manufacturer’s

recommendations.

Lock-out the gas and the electrical power to the

unit before performing any maintenance or service

operations to this unit.

V-Belt Drives

V-belt drives must be checked on a regular basis for

wear, tension, alignment, and dirt accumulation.

Check the tension by measuring the deﬂection in the

belt as shown below.

IMPORTANT

Check the alignment by using a straight edge across

both sheaves as shown below.

Do not allow water or solvents to enter the motor

or bearings. Motors and bearings should never be

sprayed with steam, water or solvents.

IMPORTANT

Premature or frequent belt failures can be caused by

improper belt tension or misaligned sheaves.

Greasing motors is only intended when ﬁttings are

provided. Many motors are permanently lubricated,

requiring no additional lubrication.

• Abnormally high belt tension or drive misalignment

will cause excessive bearing loads and may result

in failure of the fan and/or motor bearings.

• Abnormally low belt tension will cause squealing

on start-up, excessive belt flutter, slippage, and

overheated sheaves.

Wheels

Wheels require little attention when moving clean air.

Occasionally oil and dust may accumulate on the wheel

causing imbalance. When this occurs the wheel and

housing should be cleaned to assure proper operation.

IMPORTANT

Do not pry belts on or off the sheave. Loosen belt

tension until belts can be removed by simply lifting

the belts off the sheaves.

Filters

IMPORTANT

Filter maintenance is generally limited to cleaning and

replacement.

When replacing V-belts on multiple groove drives,

all belts should be changed to provide uniform drive

Aluminum mesh ﬁlters can be washed in warm soapy

water.

An adhesive spray can be added to aluminum mesh

ﬁlters to increase their efﬁciency.

IMPORTANT

Do not install new belts on worn sheaves. If the

sheaves have grooves worn in them, they must be

replaced before new belts are installed.

IMPORTANT

When reinstalling filters, be sure to install them

with the airflow in the correct direction. An airflow

direction arrow is located on the side of the filters.

Belt Span

Deﬂection =

IMPORTANT

Replacement filters should be from the same

manufacturer and the same size as the original

filters provided with the unit.

Belt Span

Belt Tension

Drive Alignment

Model VSU Make-Up Air

Maintenance - Fall

Bearings

Start-Up

Repeat the Blower Start-Up Step #5 and Direct Gas Start-

Up Steps #1 through #4. This will ensure that the gas and

air are set properly before the heating season begins and

should lead to trouble free operation all winter.

The bearings for Greenheck fans are carefully selected

to match the maximum load and operating conditions

of the speciﬁc class, arrangement and fan size. The

instructions provided in this manual and those provided

by the bearing manufacturer will minimize any bearing

problems.

High Limit

The high limit switch may have tripped over the

summer; it should be checked and reset if necessary.

IMPORTANT

Burner

Lubricate bearings prior to periods of extended

shutdowns or storage and rotate shaft monthly to

aid in corrosion prevention. If the fan is stored more

than three months, purge the bearings with new

grease prior to start-up.

Inspect the burner for accumulation of scales on both

the upstream and downstream sides of the mixing

plates. Any scaling or foreign material should be

removed with a wire brush.

Visually check that all holes in the mixing plates are clear.

If any burner ports are plugged (even partially), clear

them with a piece of wire or another appropriate tool.

Recommended Bearing Lubrication Schedule (in Months*)

Bearing Bore Size (inches)

Fan

RPM

⁄2

-1

1¹⁄8 -1¹⁄2

1⁵⁄8 - 1⁷⁄8 1¹⁵⁄16 -2³⁄16

2⁷⁄16 -3

Replace or tighten any loose or missing fasteners on

the mixing plates. Always use zinc plated or stainless

steel fasteners.

750

*Suggested initial greasing interval is based on 12 hour per

day operation and 150°F maximum housing temperature.

For continuous (24 hour) operation, decrease greasing

interval by 50%

Inspect and clean the ﬂame and spark rod. Occasional

replacement of the ﬂame rod and spark rod may be

necessary to ensure optimum unit performance.

• If extended grease lines are present, relubricate while in

operation, only without endangering personnel.

WARNING

• For ball bearings (operating) relubricate until clean grease

is seen purging at the seals. Be sure not to unseat the seal

by over lubricating.

• For ball bearings (idle) add 1-2 shots of grease up to

2 inch bore size, and 4-5 shots above 2 inch bore sizes

with a hand grease gun.

• For roller bearings add 4 shots of grease up to 2 inch bore

size, and 8 shots for 2-5 inch bore size with a hand grease

gun.

Do not enlarge burner ports when clearing a

blockage, performance could be affected.

NOTE

Flame rods can last many years, but because of

thermal expansion of the porcelain, flame rods can

fail over time.

• Adjust relubrication frequency based on condition of

purged grease.

• A high quality lithium based grease conforming to NLGI

Grade 2 consistency, such as those listed here:

Mobil 532

Mobilux #2

Texaco Multifak #2

Texaco Premium #2 Exxon Unirex #2

B Shell Alavania #2

Model VSU Make-Up Air

Reference

Typical Control Center Layout

1. Spark Generator

7. Motor Fuses

2. Temperature Selector

3. Ampliﬁer

4. 24V Transformer

5. 120V Transformer

6. Transformer Fuses

8. Heating Inlet Air Switch

9. Flame Safeguard

10. High Limit Switch

11. Disconnect

12. Soft Start

Typical Gas Train Layout

High/Low

Gas Pressure

Airﬂow Switch*

View Port

Pilot Solenoid

Valve

Modulating

Valve

Pilot Regulator

Manual Shutoff*

Hand

Valve

Gas Supply

Connection

Fluid Valve

*Two are provided on Canadian units.

Model VSU Make-Up Air

Reference

Start-Up Checklist

Start-Up Direct Gas – refer to Direct Gas Start-

Up section for further detail.

Unit Model Number _______________________________

(e.g. VSU-220-H40-UB)

o Check supply gas pressure

________ Maximum

________ Minimum

Unit Serial Number _______________________________

(e.g. 04c99999 or 10111000)

Start-Up Date

_______________________________

________ Actual

Start-Up Personnel Name__________________________

Start-Up Company _______________________________

o Check Pilot Gas Pressure

________ Actual Setting

Typical 3.0 inch wc

Phone Number

_______________________________

o Set optional High Gas Pressure Switch

________ Actual Setting

Typical 8.0 inch wc

Pre Start-Up Checklist – check boxes as items

are completed.

o Check tightness of all factory wiring connections

o Verify control wiring wire gauge

o Hand-rotate blower to verify free rotation

o Verify supply voltage to the main disconnect

o Verify the supply gas pressure

o Set optional Low Gas Pressure Switch

________ Actual Setting

Typical 3.0 inch wc

o Set Burner Pressure Differential

________ Actual Setting

Typical 0.65 inch wc

o Set the maximum firing rate

________ temp rise

o Verify remote controls wiring

Start-Up Blower Checklist – refer to Blower

Start-Up section for further detail.

o Check line voltage

L1-L2 __________

L2-L3 __________

L1-L3 __________

o Set the minimum firing rate

________ check

o Check blower rotation

o Check for vibration

o Supply fan RPM

o Motor nameplate amps

o Actual motor amps

o Actual CFM delivered

o Set the unit’s operating temperature

________ ºF

_________ RPM

_________ Amps

_________ CFM

Optional Accessories – refer to Blower Start-Up

section, Step #6 for further detail.

o Heating Inlet Air Sensor

________ Actual Setting

Typical setting 60º-70ºF

Model VSU Make-Up Air

Maintenance Log