Chromalox PQ404 6 User Manual

Installation, Operation  
and  
4
CHS  
(Supersedes PQ404-5)  
PQ404-6  
RENEWAL PARTS IDENTIFICATION  
161-048642-001  
OCTOBER, 1983  
Horizontal Electric Steam Boiler  
Model Number CHS 0 – 150 PSI  
Boiler Serial No . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Power Circuit Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Model No. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . No. of Power Circuits . . . . . . . . . . . . . . . Amps. . . . . . . . . . . . . . . . . . . .  
Electrical Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Control Circuit Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
National Board No . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Total Amps . . . . . . . . . . . . . . . Phase . . . . . . . . . . . . Cy . . . . . . . . . . . . .  
IMPORTANT – This data file contains the National Board Registration Certificate approving your generator. It must be kept near the generator at all times.  
Specifications — 480 Volt Boilers*  
Power CC Size of  
Output  
Standard Lbs. per  
Nominal  
Size  
90˚C  
Wire  
Amps  
per  
Model  
B.H.P.  
Fuse Delta  
Elements Control  
Hr. at  
Number Rating kW Contactors Size kW  
(Amps) (M.C.M) Circuit  
(kW)  
System 212˚F  
2
1
3
3
1
4
4
1
5
2
3
4
1
60  
CHS-150* 15.3 150  
CHS-180* 18.4 180  
CHS-210* 21.4 210  
CHS-240* 24.5 240  
CHS-270* 27.6 270  
5
6
7
8
9
50A 60A  
50A 60A  
50A 60A  
50A 60A  
50A 60A  
30  
30  
30  
30  
30  
30  
30  
1
1
1
1
1
1
2
300  
300  
600  
600  
600  
600  
300  
4/0  
250  
600  
400  
600  
600  
250  
181  
217  
253  
290  
326  
362  
217  
452  
543  
633  
723  
814  
904  
1085  
30  
30  
60  
30  
60  
60  
30  
60  
90  
60  
90  
60  
CHS-300* 30.6 300 10 50A 60A  
CHS-360  
CHS-420  
36.7 360 12 50A 60A  
42.9 420 14 50A 60A  
30  
2
600  
350  
254  
1266  
3
1
4
135  
90  
135  
CHS-495  
CHS-540  
50.5 495 11 60A 100A 45  
55.1 540 12 60A 100A 45  
2
2
600  
600  
500  
600  
297  
324  
1492  
1628  
4
1
5
1
135  
90  
135  
45  
CHS-630  
CHS-720  
64.3 630 14 60A 100A 45  
73.5 720 16 60A 100A 45  
2
3
600  
600  
700  
400  
378  
324  
1889  
2170  
CHS-810  
CHS-945  
82.7 810 18 60A 100A 45  
96.4 945 21 60A 100A 45  
3
3
4
4
5
5
6
600  
600  
600  
600  
600  
600  
600  
600  
700  
500  
700  
600  
700  
600  
324  
378  
324  
378  
324  
378  
324  
6
7
8
9
135  
135  
135  
135  
2441  
2848  
3255  
3662  
4069  
4476  
4883  
CHS-1080 110.0 1080 24 60A 100A 45  
CHS-1215 124.0 1215 27 60A 100A 45  
CHS-1350 138.0 1350 30 60A 100A 45  
CHS-1485 152.0 1485  
CHS-1620 165.0 1620 36 60A 100A 45  
CHS-360 Steam Boiler  
10 135  
11 135  
12 135  
3
60A 100A 45  
*150 kW Thru 300 kW Boilers available in 280V and 240V. Check Factory  
INSTALLATION  
3. When any type of feed other than a pump feed is used – the exist-  
ing water supply must be 10 pounds greater than the boiler operat-  
ing pressure to assure water supply maintains proper water level in  
boiler. Otherwise, lack of water can cause heater failure. Keep feed  
water line valves open at all times.  
CAUTION: To avoid electrical shock hazard, boilers  
must be suitably grounded to earth.  
NOTE: Chromalox boilers are pre-tested before shipment; no internal  
piping or wiring is necessary. WARNING: Substitution of compo-  
nents or modification of wiring without prior consent of Chromalox,  
Inc. voids warranty.  
1. Locate unit on level floor or platform. NOTE: A minimum dis-  
tance of 60 inches from wall, other equipment, etc. must be  
allowed for removal of the elements.  
2. Complete all piping to boiler. Connect water line to tagged fitting  
on the motor and pump assembly, if used, or to tagged fitting on  
water control feeder.  
4. All water feed systems are connected to supplied water inlet check  
valve.  
5. Connect steam line (with Globe valve) to boiler steam outlet. Valve  
should be placed as close as possible to boiler outlet.  
6. To insure maximum efficiency of supplied kw, all piping from out-  
let should be insulated.  
7. Drain and relief valve piping should be in accordance with state  
and local codes.  
© 2010 Chromalox, Inc.  
INSTALLATION (cont’d.)  
SPECIAL INSTRUCTIONS FOR CUSTOMERS SUPPLYING  
L
THEIR OWN CONDENSATE OR PUMP SYSTEMS.  
1. Check the voltage of the motor before making the wiring connec-  
tion. Some Chromalox boilers are supplied with dual voltage sys-  
tems. The motor should always match the voltage of the control  
circuit.  
1” Condensate  
Return  
1” Vent  
2. The motor circuit should be wired into the pump control as shown  
1/2”  
Water  
Line  
in wiring diagram.  
3. A heavy-duty vacuum breaker is required when condensate system  
is used. (part number ES-89369)  
H
Strainers  
1” Outlet  
to Boiler  
Width – 6-1/2  
1” Drain  
to Boiler  
1” Discharge  
1/2” Water Line  
1/2” Solenoid  
Motor and  
Pump  
“W” Dimension – Overall Width  
Model  
Max.  
PSI  
Tank Cap.  
(Gal.)  
6-5/8”  
5-7/8”  
4-1/4”  
Number  
L
H
W
CHS-150  
thru  
CHS-300  
125  
150  
33  
40  
33-1/4  
41-1/2  
41-1/2  
21  
3”  
7-1/4”  
1/2” Strainer  
CHS-360  
thru  
CHS-420  
15-1/4” for CHS-150  
16-3/8” for CHS-180 to 300  
40  
21  
Figure 4 – Motor and Pump Assembly  
Figure 5 – Condensate Return System  
WIRING  
1. Wiring to boiler should be as per appropriate wiring diagram sup-  
plied with boiler and in accordance with Local and National  
Electrical Codes.  
2. SAFETY SWITCHES - Purchaser should use a safety switch  
between his main power source and the boiler. The safety switch  
should use circuit breakers or fuses and be in accordance with  
NEC and local codes.  
water cutoff to energize the shunt mechanism on the safety switch.  
This is an additional safety feature that prevents a dangerous situ-  
ation should a contactor or relay stick. Activation of the shunt trip  
device will completely disconnect the boiler from the power sup-  
ply. (See Figure 7).  
3. Since boiler heating elements are susceptible to lightning damage,  
plants not having lightning arresters that have above-ground elec-  
trical cable supply sources should install lightning arresters in the  
proper size to meet the boiler kw load.  
Serious thought should be given to the advisability of using a shunt  
trip safety switch of the circuit breaker type as an additional safe-  
ty precaution. It is possible to utilize the spare contacts in the low  
To Aux.  
L.W. C.O.  
Shunt Trip Device  
(Supplied by Others)  
To L2 on  
Terminal Strip  
Operating  
Pressuretrols  
Common  
Hi-Limit  
Pressuretrol  
To Field  
Supply  
Voltage  
Wiring  
Input  
Terminal  
To  
L2  
To Main  
Switch  
L.W.C.O. &  
Pump Control  
To Motor Starter  
To Aux.  
L.W.C.O.  
*Standard on CHS-150 to CHS-300 units in lieu of step  
sequencer and operating pressuretrol shown in Figure 8  
Figure 6 – Pressuretrol Control System*  
Figure 7 – Safety Switch (Field Installed)  
3
WIRING (cont’d.)  
Figure 8 – Typical Wiring Diagram  
Power Circuit  
Terminal Block  
Electronic Resistance  
Sensing Amplifier for  
Auxiliary Low Water Cutoff  
To  
To Other  
Heater  
Groups  
Power  
Curcuit  
Relay  
120 Volt  
Control Voltage  
Hi Limit  
Control  
To  
Other  
Heater  
Groups  
Step  
Sequencer  
Low Water  
Probe  
Typical 3 Phase Heater Group  
Figure 9 – Power Circuit Detail  
Figure 10 – Auxiliary Low Water Cutoff  
4
PRE-OPERATION CHECK  
B. ADJUSTING OPERATING PRESSURE CONTROLS  
Cut-Off and  
1. Chromalox boilers are supplied with operating and high limit pres-  
sure controls. One is used for controlling the operating pressure of  
the boiler while the other is used as a high limit control. To deter-  
mine the difference in the controls, the high limit has a manual  
reset lever on top of the case. Also, there is no differential scale  
present.  
Pump  
Alarm Switch  
Low Water  
Cut-Off  
Terminals  
Adjusting  
Screws  
Alarm  
Circuit  
Terminals  
2. On all controls, the pressure adjusting screw on the top of the case  
sets the desired pressure. Turning the screw counterclockwise  
reduces the pressure setting (see Figure 12). High limit control  
should be set at 10 psig above the operating pressure of the boiler.  
3. The differential adjusting screw on the operating control is set in  
the same manner as the pressure adjusting screw. This scale set-  
ting, plus the main scale setting, equals cutout pressure of the oper-  
ating control. (Scale A thru F equals 3 psi per letter. L9l B only)  
L404A Differential is indicated on Scale Plate.  
Pump  
Circuit  
Terminals  
Pump  
Switch  
Line  
Figure 11 – Automatic Reset Low Water Cutoff Junction Box  
NOTES  
Pressure  
Adjusting  
Screw  
1. Motor, Solenoid Valve and Dotted Control Wiring are included if  
Motor and Pump package is supplied. Solenoid Valve only is sup-  
plied with 99117 Water feed.  
Mercury  
Switch  
Differential  
Adjusting  
Screw  
2. 1/3 HP Motor is controlled directly without use of Motor Starter.  
Differential  
Setting  
Indicator  
After proper wiring and piping of boiler system is complete, testing of  
controls can start. Before testing controls, it is recommended that all  
contactor fusing be removed. This is to prevent possible element fail-  
ure under test conditions.  
Pressure  
Setting  
Indicator  
CAUTION: Be sure all electrical connections are tight  
before energizing boiler. Reset all manual reset con-  
trols by pushing reset buttons on: (1) high limit control  
located on top of boiler and (2) McDonnell-Miller locat-  
ed on side of boiler.  
Operating Lever  
Diaphragm Assembly  
Index Mark  
Pointer  
Leveling  
Indicator  
Figure 12 – Pressure Control  
A. McDONNELL & MILLER LOW WATER CUTOFF CON-  
TROL OPERATION AND TESTING  
To check operation of the controls, close steam outlet valve and  
adjust operating pressure control to a low pressure setting. Also,  
set high limit control at 10 psig above operating pressure control.  
1. Be sure all valves from incoming water supply are fully open. Turn  
boiler switch to “ON” position, pump or solenoid valve will ener-  
gize, allowing boiler to fill with water. Proper water level is auto-  
matically reached with level control supplied. Pump or solenoid  
feed will shut off at proper water level. Contactor(s) will energize,  
supplying power voltage to elements.  
Turn on boiler and allow pressure to build up. When pressure  
gauge reading approaches set point of pressure control, the switch  
will trip and shut off boiler. Turn boiler main switch to “OFF".  
2. Checking operation of pump switch. (Figure 11) With water level  
visible in sight glass, partially open drain valve at bottom of boil-  
er. If automatic blowdown supplied, push manual blowdown  
switch until valve open light is on, hold for few seconds. Water  
level will fall, allowing float to trip pump switch to “ON” position.  
Close drain valve or release manual blowdown switch. Pump  
motor or solenoid valve will energize and water level will resume  
to normal level in sight glass.  
3. Checking low water cutout switch operation, open drain valve  
completely. If automatic blowdown supplied, push in and hold  
manual blowdown switch until water level falls enough to trip  
cutout switch. Close drain valve or release manual blowdown  
switch. If low water cutout is automatic reset, pump or solenoid  
will return water level to normal. If low water cutout is manual  
reset, then manual reset button on McDonnell & Miller low water  
cutoff control must be pushed to complete circuit. Turn off boiler.  
Reinstall contactor fuses.  
To reset pressure control, bleed off enough pressure in the boiler  
by opening steam outlet drain, or blowdown valve to allow the  
operating control to reset.  
4. HIGH LIMlT PRESSURE CONTROL OPERATION. The  
high limit is tested in the same manner but with the operating con-  
trol set above the pressure setting of the high limit. (Figure 13)  
CAUTION: THIS IS FOR TEST PURPOSES ONLY!  
When the high limit trips turn off boiler and reset high limit to  
proper setting, the manual reset level must be pushed to resume  
operation upon startup.  
Manual  
Reset  
Lever  
Pressure  
Adjusting  
Screw  
Mercury  
Switch  
Scaleplate  
Pressure  
Setting  
Indicator  
Pump  
Index  
Mark  
For pump motors 1/2 h.p. Single Phase  
or less, or D.C. 1/4 h.p. or less,  
wire as main line switch.  
Operating Lever  
Leveling  
Indicator  
Pointer  
Diaphragm  
Assembly  
Line  
Wiring Diagram – McDonnell & Miller Low Water Cutoff and Pump Control  
Wiring Diagram – McDonnell & Miller Low Water Cutoff and Pump Control  
5
OPERATION  
RECOMMENDED START-UP PROCEDURES  
1. Close globe valve on outlet side of boiler. (Customer Supplied)  
2. Turn on boiler and allow pressure to build up to operating  
pressure.  
3. Only open globe valve by quarter turns at first, introducing small-  
er amounts of steam into process. Avoid opening globe valve all at  
once. This will eliminate the possibility of evacuating the boiler of  
water caused by the suddenly increased boiling of the water in the  
vessel as the pressure is reduced. On boilers where constant pres-  
sure is not maintained, globe valve should be kept partially closed.  
This will maintain a constant head on the boiler and stabilize any  
fluctuation in boiler water level.  
NOTE: For best boiler performance, a steam valve 1/4” smaller  
than size of safety valve should be plumbed as close as practicable  
to steam outlet.  
Timer  
Figure 14 – Automatic Blowdown Control Cabinet  
MANUAL BLOWDOWN INSTRUCTIONS  
Blowdown is an essential part of boiler operation. It is the best pre-  
ventive maintenance you can give your boiler and will add years of life  
to the unit. Make sure a blowdown schedule is established and fol-  
lowed regularly.  
The unit may also be used to blow down boilers which run continu-  
ously, day and night.  
INITIAL TESTING - Set the switch marked “Boiler Normal/24-  
In extremely hard water areas blowdown is necessary once a day.  
In soft water areas, once each week. If there is a particular problem  
which applies to your own local water condition other than mineral  
content, take this into consideration in determining which schedule is  
to be followed.  
1. At the end of the working day, while boiler is still operating, turn  
switch to the OFF position and close water supply valve. De-ener-  
gize wall mounted safety switch.  
hour duty” located on the panel box to the “Boiler Normal” position.  
On the large timer set the “ON” tab to 8 AM and the “OFF” tab to  
8 PM. Set the small, time delay relay to “0".  
Turn the larger timer by hand until the “ON” tab passes the “TIME  
NOW” indicator so that the “TIME NOW” arrow indicates 10AM.  
Energize the main feed to the “line terminals” of the unit. The  
“boiler normal” pilot light as well as the “drain valve closed” light  
should glow.  
2. If blowing-down into a receptacle, allow pressure to decrease to  
15-20 psi before opening blowdown valve.  
Hold down the “drain” button for about six seconds. The “boiler  
normal” light should go out immediately as well as the “drain valve  
closed” light. It takes about 4 seconds for the drain valve to open fully  
at which time the “drain valve open” light should light. As soon as the  
“drain” button is released, the valve begins to close. When it reaches  
the closed position, the “drain valve closed” light and the “boiler nor-  
mal” light should light up again.  
3. It is preferable to connect the blowdown valve directly into a  
drainage system. If this is done, the boiler can be discharged at  
operating pressure.  
4. When discharge is complete and boiler is drained –  
a. close the blowdown valve;  
b. open water supply valve;  
c. put boiler switch to the “ON” position; and, (d) close wall  
mounted safety switch.  
Pilot Lights and Switches  
5. When refilling is complete turn off the boiler switch unless further  
operation is desirable.  
6. If you have been supplied with a Manual Reset Low Water control  
as required in some states, the reset button on the control must be  
pushed before boiler will begin developing pressure. (Do not push  
reset until boiler has filled with water.) The use of chemical boiler  
cleaning compounds in these boilers voids all warranties unless  
approved by manufacturer. Some compounds will damage copper-  
sheathed heating elements, thereby shortening their life.  
Boiler Normal  
Valve Open  
Valve Closed  
AUTOMATIC BLOWDOWN INSTRUCTIONS  
Toggle Switch  
(IF FURNISHED) (See Figures 14 and 15)  
The Automatic Blowdown is a device which automatically starts  
up your boiler in the morning; shuts it down at night and blows down  
(partially drains) the main boiler drain and the low water cut-off col-  
umn for a predetermined time interval each working day.  
Manual Drain Push Button  
Valve Actuator  
The heart of the unit is an electrically operated straight through  
type ball valve. It is specially designed to handle dirty, corrosive fluids  
and particles without requiring cleaning or the use of a strainer.  
Both the valve and the boiler are controlled by an electric control unit  
which indicates with pilot lights when the drain valve is in the opened  
or closed position and when the boiler is ON or OFF. In addition to the  
automatic control function, the unit has a push button which momen-  
tarily de-energizes the boiler and opens the drain valve regardless of  
the time of day.  
Motor Drain  
Ball Valve  
Figure 15 – Display View of Automatic Blowdown Control Cabinet  
6
OPERATION (cont’d.)  
Now turn the wheel on the large timer until the “off” tab passes the  
Set the tabs on the large timer for the ON and OFF times desired  
for the boiler, screw in the small black day-skip tabs if the boiler is to  
remain off for the weekend, etc.  
“time now” arrow. The “boiler normal” light should go out and the  
valve should begin to open. Once the “valve open” light goes on, the  
valve should remain open for a few seconds and then automatically  
close. The “drain valve closed” light should light and the “boiler nor-  
mal” light should remain off.  
If the boiler is on 24-hour duty set the OFF tab for the time that is  
desired for blowdown. The ON tab can be ignored, but must remain on  
timer.  
NORMAL OPERATION – Set the “Boiler Normal/24-hour duty”  
switch located on the inside of the control panel to “boiler normal” if  
the boiler is to be shut down each night. Set it to “24-hour duty” if the  
boiler is to remain on continuously 24 hours per day (except during  
blowdown).  
The small time delay relay controls the time that the drain valve  
remains open. Counterclockwise decreases, clockwise increases blow-  
down time. Time must be adjusted by trial.  
Figure 16 – Typical Wiring for Automatic Blowdown System  
7
OPTIONAL EQUIPMENT FOR CHROMALOX STEAM BOILERS  
AUXILIARY LOW WATER CUT-OFF  
“min” to “F”. The value of each division varies with the scale range of  
the instrument.  
(See page 4 for Wiring Diagram)  
Operation  
Operation of this control is accomplished by sensing a minute AC  
current flowing between submerged contact probe in the boiler shell.  
Pressure  
Scale Rating  
0-15 psi  
Value Each  
Division on Scale  
2.2 psi  
When this minute AC current is conducted through an external cir-  
cuit resistance up to 100,000 ohms or less, a signal of sufficient mag-  
nitude is present to trigger the SCR and, in turn, energize the control  
relay.  
5-150 psi  
3.6 psi  
Pressure scale rating will vary depending on pressure control supplied.  
CHECKOUT  
As the water level in the boiler drops below the level of the probe.  
the AC circuit is broken and the control relay is de-energized. The con-  
trol will not energize until sufficient water is present in the boiler.  
After the controller has been installed, wired, and set, it should be  
tested with the system in operation. First allow the system to stabilize.  
Then observe the operation of the controller while raising and lower-  
ing its set point. Pressure should increase when the set point is raised  
and decrease when the set point is lowered. Use accurate pressure test-  
ing equipment when checking out the controller. Do not rely on inex-  
pensive gauges. The controllers are carefully calibrated at the factory.  
Specifications  
Input supply....................120 vac/50-60 hz  
Delectable Range............100.000 ohms  
Probe Voltage..................24 vac  
Probe Current..................10 milliamps  
Control Relay ................Single pole double throw  
If the motor or actuator runs in the proper direction when the set  
point is adjusted, it can be assumed that the controller is operating  
properly. If it runs in the wrong direction, reverse the B and W wires.  
Observe the action of the motor to see if it stabilizes. If the motor is  
moving constantly, widen the proportioning range a little at a time,  
until the system is stable.  
CAUTION: Control will not work with de-ionized or  
demineralized water.  
PROPORTIONING PRESSURE CONTROL (See Figure 17)  
Typical Operation  
Pressure variations cause the bellows to expand or contract.  
Linkage between the bellows and the potentiometer wiper causes the  
wiper to move across the windings on the potentiometer. This varies  
the resistance between R and B, and between R and W, causing an  
imbalance in the circuit connected to the controller.  
Differential  
Adjusting Screw  
Adjusting Screw  
A proportioning pressure control is used to regulate a motor driven  
or solid state sequencer. The controller potentiometer, the feedback  
potentiometer in the motor and a balancing relay in the motor form an  
electric bridge circuit. As long as the pressure of the controlled medi-  
um remains at the set point of the controller, the circuit is balanced;  
i.e., equal currents flow through both sides of the balancing relay and  
the relay contacts are open. When the circuit is balanced, the motor  
does not run.  
R
W
B
If the pressure of the controlled medium rises, the wiper in the con-  
troller moves toward W. This unbalances the circuit, so a larger current  
flows through one side of the balancing relay. The “close” contacts in  
the relay make, causing the motor to drive toward its closed position.  
As the motor runs, the wiper on the feedback potentiometer moves in  
a direction balance, the balancing relay contacts open and the motor  
stops.  
Similarly, if the pressure of the controlled medium falls, the wiper  
on the controller potentiometer moves toward B, and the “open” con-  
tacts in the balancing relay make. The motor drives toward its open  
position until circuit balance is achieved.  
Figure 17  
(L91B) Proportioning Pressure Control Used with Sequencer Control  
The slightest change in the pressure of the controlled medium will  
cause a change in the number of elements energized to compensate for  
it, thus keeping the pressure constant. This process is called modula-  
tion.  
IF A CONTROLLER SEEMS  
TO OPERATE IMPROPERLY (See Figure 18)  
If the controller is suspected of operating improperly, it may be further  
checked as follows.  
PROPORTIONAL PRESSURE CONTROL ONLY  
SUPPLIED WITH SEQUENCER  
1. Leave the controller installed where it is, but disconnect all power  
Main Setting - Turn the adjustment screw until the indicator is  
opposite the low point of the desired throttling range. That is, if the  
pressure is to be held to a minimum of 50 psi, set the indicator at 50  
psi. The pressure will then be maintained between 50 psi and a higher  
pressure equal to the 50 psi plus the throttling range.  
to the controlled motor.  
2. Loosen the cover screw below the main scaleplate and remove the  
cover.  
3. Disconnect the wires from the controller.  
4. Connect an ohmmeter between controller terminals 8 and W to  
measure the resistance of the potentiometer in the controller. The  
ohmmeter should read about 135 ohms on an L91B.  
THROTTLING RANGE SETTING L918  
After setting the indicator for the minimum pressure, turn the throt-  
tling range adjustment screw until the throttling range indicator points  
to the desired throttling range on the scale. This scale is graduated from  
8
OPTIONAL EQUIPMENT FOR CHROMALOX STEAM BOILERS (cont’d.)  
5. Connect the ohmmeter between controller terminals W and R and  
raise the set point of the controller above the actual pressure being  
measured. The ohmmeter should read the full value of the poten-  
tiometer measured in step 4 (135 ohms for an L91B).  
TESTING OPERATION OF SEQUENCER (See Figure 20)  
1. With boiler off, remove wiring from pressure control on sequencer  
low voltage terminal board.  
2. Turn on boiler to supply the voltage to sequencer. Short terminal R  
and B for counter-clockwise rotation and terminal R and W for  
clockwise rotation.  
6. Slowly lower the set point of the controller while observing the  
ohmmeter reading. The resistance should drop to zero at some set  
point below the actual pressure.  
3. If sequencer operates under this test procedure, but when rewired  
to pressure controller, does not function, check pressure control.  
Note that wiring is W-B and B-W-R-R between sequencer and  
pressure control.  
7. An approximation of the proportioning range can be made by  
observing the change in set point required for a resistance change  
from zero to full value.  
8. When the controller is operating properly, reconnect the wires,  
replace the cover. tighten the cover screw, and reset the controller  
to the desired value.  
9. Reconnect power to the controlled motor.  
Main Scale  
Adjusting Screw  
Proportioning Range  
Adjusting Screw  
R
W
B
Main Scale  
Setting  
Indicator  
Setpoint  
Ohmmeter  
W
R
B
Increases  
to 15 Ohms  
Note: Terminals are not labeled, but screw-heads are  
color-coded red (R), white (W) and blue (B).  
Figure 18  
BOILER SEQUENCER (5 STEP)  
RECYCLE FEATURE (See Figure 19)  
The step control is designed to drop out all contactors when con-  
trol circuit is interrupted. On resumption of power, the camshaft rotates  
to the counter-clockwise (ccw) limit, opening all the load switches.  
The recycle relay then energizes, pulling in the load contact, and final-  
ly the camshaft rotates clockwise (cw) to the position called for by the  
pressure controller energizing, in sequence, the required load stages.  
Figure 20  
Typical Wiring Diagram for 5 Step Motor Driven Sequencer  
SEQUENCE REVERSER (See Figure 21)  
GENERAL:  
Sequence Reverser is an automatic switching device which is  
interposed on an electric boiler between the proportional sequence  
controller and the heating element contactors. The device is periodi-  
cally actuated to alter the operating sequence of each of the heating  
elements, thereby increasing the overall reliability of the boiler.  
DETAILS:  
The Sequence Reverser consists of an eight-day timer set up for  
four days on and four days off which energizes and de-energizes dou-  
ble throw relays which are wired to reverse the “firing” order of the  
heating element contactors with each operation of the timer.  
Figure 19 – Five Step Sequencer  
9
OPTIONAL EQUIPMENT FOR CHROMALOX STEAM BOILERS (cont’d.)  
The Sequence Reverser accomplishes its tasks and shows the rela-  
tive use of each of ten beat stages during the first four days of the  
cycle. This is how the work load would be distributed on a boiler with-  
out Sequence Reverser. It can be seen the early stages are ON most of  
the time and the later stages are OFF most of the time, since they are  
used only during heat load peaks. (This analysis assumes hours of use  
directly affecting component life. Frequency of on/off operations has  
been ignored because of the limited in-rush associated with beating  
elements and because of the relative independence of contactor life on  
number of operations in the resistive load situations.)  
Solid State Progressive Sequencer (See Figure 22)  
The solid state progressive sequencer provides accurate electronic  
control of multi-stage loads of the type used in Chromalox steam boil-  
ers. It features progressive sequencing (first on-first off) which equal-  
izes the operating time of each load. This control gives visual indica-  
tion of each energized stage by means of integral solid state light emit-  
ting diodes. In the event of power interruption all heating elements are  
immediately de-energized for safety. When power resumes, the control  
will re-stage the loads one at a time. Refer to the diagram for visual  
description of progressive sequencing.  
It is clear, without sequence reversing, the early stages would tend  
to fail long before the later stages. The sequence reverser essentially  
equalizes the relative usages of heating stages. It can be seen, without  
the sequence reverser the first heat stage is used approximately twice  
as much as it is with the sequence reverser. This means the boiler will  
be likely to have its first element failure in half the time without  
PROGRESSIVE SEQUENCING  
The solid state sequencer operates on 120 V AC/60 Hz and each  
output is relay switched with a load rating of 125 VA at 120 VAC.  
Figure 21 – Five Step Sequence Reverser  
sequence reverser as compared to the boiler with sequence reverser. In  
addition. boilers without sequence reverser will have many failures  
spread over a long time while boilers with sequence reversing will  
require element changes at roughly the same time. (See wiring dia-  
gram on Page 4).  
Figure 22 – Solid State Sequencer  
MAINTENANCE  
4. A check for water or steam leaks should also be made and any  
CAUTION: Hazard of electric shock. Disconnect all  
power before working on boiler.  
loose fittings immediately tightened.  
5. If boiler is equipped with a Solid State Auxiliary Low Water  
Cutoff, every four months the probe should be checked for  
deposits and cleaned, if necessary. This is accomplished by remov-  
ing the inspection plate, removing the probe (with a standard  
sparkplug wrench) cleaning and replacing.  
Chromalox Electric Steam Boilers are designed for years of trou-  
ble-free performance. To establish a good preventative maintenance  
program, we suggest the building maintenance man or engineer famil-  
iarize himself with these simple rules:  
1. The use of specific boiler cleaning compounds cannot be recom-  
mended. We do recommend that a reputable firm of water treat-  
ment engineers be consulted regarding conditioning boiler water.  
Proper selection must be made of a compound to prevent damage  
to copper sheath heating elements.  
Note: The system will not operate if the boiler is using distilled,  
demineralized or deionized water.  
At the same time, one of the bottom heating elements should be  
removed. If scale has begun to form, all elements should be  
cleaned and boiler drained and flushed.  
2. The sight glass should be checked daily to ensure the boiler has  
adequate water.  
6. IMPORTANT: The Manufacturers' Data Report enclosed within  
the instruction sheet is very important and must be put in a safe  
place. You may be called upon to produce it by a State agency.  
3. A monthly inspection should be made of the internal wiring. All  
electrical connections should be checked for lightness.  
10  
MAINTENANCE  
INSTRUCTIONS FOR ELEMENT REPLACEMENT  
2. On automatic feed units, close valve on incoming water line. Drain  
CAUTION: Before installing your new elements, be sure the  
McDonnell-Miller low-water cut-off is operating perfectly and the  
float chamber and lower equalizer column are completely clear of  
sludge or other foreign matter. (See Figure 23)  
boiler completely of water.  
3. Open boiler door to expose heating element.  
4. Disconnect wire (electric) leads connecting element to main power  
system of boiler. Again note wire connections to facilitate re-  
assembly. Proceed to remove (6) 5/16-18 bolts from flange.  
Failure to do this may cause the immediate burnout of the new ele-  
ments.  
5. Thoroughly clean boiler flange of all foreign material. Be certain  
All elements are thoroughly checked before shipment. The manu-  
facturer cannot be responsible for burnouts caused by a faulty low-  
water cut-off.  
no part of old gasket remains on boiler flange.  
6. Apply “Slic-Tite” Gasket Compound (or equal) to both surfaces of  
new gasket supplied with replacement element. Proceed to install  
element flange assembly with gasket between boiler flange and  
clement flange. In doing this, be careful to align flange holes so  
wire connection terminals on element assembly are in line with  
previously disconnected wire leads to facilitate easy connections.  
1” Steam Equalizing Pipe  
Pump and low water control  
7. When all (6) flange bolts are tight, connect all wires to terminals.  
Make certain wires are clean and bright to assure good electrical  
contact and nuts on screws are firmly secured.  
Normal Boiler  
Water Line  
CAUTION: Bolts should be lightened 10 a torque of 22 ftlbs.  
Cut-off Level is  
arrow mark  
8. Open water valve so water supply can reach boiler feed mecha-  
nism.  
Blowdown  
Valve  
9. Put main safety switch to “on” position.  
10. Turn boiler switch to “on” position.  
11. As boiler automatically refills, observe the new flange assembly  
for possible leaks. If water is noticed, the bolts must be retightened.  
Before doing this, turn the boiler off at the main fuse safety switch.  
1” Water equalizing pipe  
Figure 23  
The lower equalizer column can best be examined by breaking the  
unions on either side and then visually and manually examining the  
piping with your fingers or probes to see if it is clear and clean.  
12. As boiler is heated to working pressure, check flange assembly  
again for leaks.  
CAUTION - Avoid use of chemical cleaning compounds.  
Follow maintenance instructions.  
READ COMPLETELY BEFORE STARTING WORK  
1. Disconnect boiler from electric power supply at main safety switch  
or fuse panel. Then turn boiler switch to “off” position.  
RENEWAL PARTS IDENTIFICATION  
11  
RENEWAL PARTS IDENTIFICATION (cont’d.)  
AUTOMATIC FEED PUMP CONTROLLER  
Bellows Base  
Clamp Assembly  
2 Wire  
Switch  
Junction Panel  
3 Wire  
Switch  
Bellows Assembly  
with Gasket  
Bellows Base Clamp  
and Bellows Assembly  
Low Water Cutoff and Water Feed Controls  
Description  
Part Number  
Sylphon Bellow  
Assembly  
Complete Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Complete Assembly (Manual Reset) . . . . . . . . . . . . . . . . . . . . . . . .  
Complete Head Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Complete Head Mechanism (Manual Reset) . . . . . . . . . . . . . . . . . .  
Float and Rod . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Head Gasket . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
3 Wire Cut-Off and Alarm Switch . . . . . . . . . . . . . . . . . . . . . . . . . . .  
3 Wire Cut-off and Alarm Switch (Manual Reset) . . . . . . . . . . . . . .  
2 Wire Pump Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Junction Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Bellows Base Clamp & Bellows Assembly . . . . . . . . . . . . . . . . . . . .  
Bellows Base Clamp & Bellows Assembly (Manual Reset) . . . . . . .  
Bellows Base Gasket . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Bellows Base Clamp Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Bellows Base Clamp Assembly (Manual Reset) . . . . . . . . . . . . . . . .  
Bellows Assembly w/Gasket . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
B-W Auxiliary Low Water Cut-off . . . . . . . . . . . . . . . . . . . . . . . . . . .  
300-118538-013  
300-118538-026  
300-118538-027  
300-118538-028  
300-118538-029  
300-118538-030  
292-118665-003  
292-118665-004  
292-118665-002  
300-118538-031  
300-118538-032  
300-118538-033  
300-118538-034  
300-118538-035  
300-118538-036  
300-118538-037  
300-118538-038  
(See picture)  
Bellows Base Gasket  
Head Gasket  
Float and Rod  
Condensate Return Systems  
Description  
Part Number  
Condensate Return System (Comp.) 1/2 H.P.  
Heating Elements and Gaskets  
Description  
115V or 230V, 60 cy. (CHS-150) . . . . . . . . . . . . . . . . . . . . . . . . . .  
226-118656-002  
226-118656-009  
Part Number  
Condensate Return System (Comp.) 3/4 H.P.  
30kW, 3 ph, 240V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
30kW, 3 ph, 480V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
45kW, 3 ph, 480V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
45kW, 3 ph, 240V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
60kW, 3 ph, 240V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
60kW, 3 ph, 480V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
90kW, 3 ph, 480V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
135kW, 3 ph, 480V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Element Gasket . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Hand Hole Gasket . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
155-118524-040  
155-118524-021  
155-118524-041  
155-118524-042  
155-118524-026  
155-118524-022  
155-118524-023  
155-118524-043  
132-146012-002  
132-118533-004  
115V or 230V, 60 cy. (CHS-180 to CHS-300) . . . . . . . . . . . . . . . .  
(For Boilers CHS-360 through CHS-1350 check factory)  
Pressure Controls and Sequencers  
Description  
Part Number  
Pressure Control Complete . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Pressure Control Complete (Manual Reset) . . . . . . . . . . . . . . . . . . .  
Mercury Tube (Two Wire) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Pressure Control Type L91B, 0-150 . . . . . . . . . . . . . . . . . . . . . . . . .  
5 Step Proportional Sequencer . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
10 Step Proportional Sequencer . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Pressure COntrol Type L91B, 0-15 . . . . . . . . . . . . . . . . . . . . . . . . . .  
344-118529-010  
344-118529-011  
292-118665-001  
344-118529-015  
300-118538-005  
300-118538-008  
334-118529-016  
Contactors and Contactor Parts  
Description  
Part Number  
Parts for Condensate Systems – Hot Water Motors & Pumps  
Contactor (50 amp, 115V, 60 cy.) . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Contactor (50 amp, 240V, 60 cy.) . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Contactor (60 amp, 115V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Contactor (75 amp, 115V, 60 cy.) . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Contactor (75 amp, 208/240V, 60 cy.) . . . . . . . . . . . . . . . . . . . . . . .  
Relay PR 7AY, 115V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Relay PR 7AY, 230V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
072-118525-001  
072-118525-002  
072-118525-003  
072-118525-005  
072-118525-006  
072-118525-008  
072-118525-009  
Description  
Part Number  
Impeller for Pump (192 or 3/4 H.P). . . . . . . . . . . . . . . . . . . . . . . . .  
266-118671-001  
Parts for Condensate Return Systems  
Description  
Part Number  
Terminal Blocks and Fuses  
Description  
Control Circuit Fuse and Block . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Fuse Block, Class “J” 100 amp . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Power Circuit Fuse, Class “J” 60 amp. . . . . . . . . . . . . . . . . . . . . . . .  
Power Circuit Fuse, Class “J” 100 amp. . . . . . . . . . . . . . . . . . . . . . .  
Pumps and Motor, 1/2 H.P., 115 Volts or  
230 Volts, 1 ph. (CHS-150) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
226-118656-005  
Part Number  
Pump and Motor 3/4 H.P., 115 Volts or  
129-118527-001  
129-118527-003  
128-118530-003  
128-118530-004  
230 Volts, 1 ph. (CHS-180 to 300) . . . . . . . . . . . . . . . . . . . . . .  
226-118656-006  
226-118662-006  
251-118657-002  
Float Valve – 33 Gallon Tank (CHS-150 to 300 . . . . . . . . . . . . . . . .  
Seal for Pump (CHS-150 to 300) . . . . . . . . . . . . . . . . . . . . . . . . . . .  
(For Boilers CHS-360 through CHS-1350 check factory)  
Valves and Gauges  
Description  
Vacuum Breaker . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
300-118538-039  
Part Number  
Pressure Gauge 3-1/2, 160# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Gauge Glass Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Sight Glass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Safety Valve – 30#, 1” . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Safety Valve – 125#, 1” . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Safety Valve – 150#, 1” . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Check Valve – 1” Spring Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Safety Valve – 15#, 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
344-118529-024  
347-118537-002  
374-118537-009  
344-118529-006  
344-118529-020  
344-118529-025  
276-118536-003  
344-118529-008  
Limited Warranty:  
Please refer to the Chromalox limited warranty applicable to this product at  
2150 N. RULON WHITE BLVD., OGDEN, UT 84404  
Phone: 1-800-368-2493  

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