SERVICE MANUAL
4
CES
(Supersedes PQ402-5)
PQ402-6
161-049460-001
FEBRUARY, 1999
Chromalox Electric
Steam Boilers
The troubleshooting of Chromalox electric boilers can best be
placed into five major areas. These areas are: (1) fusing (2) con-
tacts, elements and voltages (3) pressure control (4) low water cut-
off (5) water feed mechanism.
of the Installation and Operating Instructions for
your specific Chromalox Electric Steam Boiler.
For convenience, we have outlined a brief description of typical
malfunctions and the area that should be explored in order to make
the proper correction. This is followed by a detailed analysis of the
five areas listed above.
WARNING: Hazard of Electric Shock and Thermal
Burns. These troubleshooting checks should only
be performed by qualified personnel after review
TYPICAL MALFUNCTIONS & PROPER CORRECTION
3. For boiler without motor and pump assembly: check pressure
of water supply to insure that it is consistently a minimum of
10 psi greater than the desired boiler operating pressure.
4. Check water inlet check valve.
5. For boiler with motor and pump assembly: check mercury
tubes in the Low Water Control.
6. A. Check motor and pump for binding and over
heating. If caught in time, this can be observed
by a humming sound. Replace if defective.
Boiler does not heat:
1. Check power fusing.
2. Examine control circuit fuse.
3. Reset button on the Low Water Control must be depressed (for
states requiring a reset button).
4. Float valve in the Low Water Control is not functioning prop-
erly.
5. Elements and/or contactors faulty.
6. Mercury tube in Low Water Control has cracked and mercury
has escaped.
B. Check for defective solenoid valve.
C. Make sure pump is running with correct rotation.
D. Check impeller adjustment on turbine type pumps.
Boiler takes too long to reach operating pressure or
does not maintain desired pressure:
Boiler appears to be leaking from beneath the jacket:
1. Check amperage on each supply leg of power harness. Reading
should correspond to a rating of not less than 10% of rated boil-
er amperage.
1. Check boiler fittings for looseness; tighten as required.
2. Check boiler fittings for cracks; replace as necessary.
3. Examine heating elements around boiler flange.
If considerable difference exists:
A. Available voltage is insufficient for boiler needs.
B. Heating element failure has occurred.
C. Fibre carrier in contactor requires replacement. On multi
contactor units, check contactors and coils to determine if
one is defective.
IMPORTANT: Leaking is a hazard, correct to prevent further
damage to other components.
Boiler overflows:
2. Check to determine whether boiler selected is underrated for
the application.
3. Additional Equipment added after initial installation, thus
undersizing boiler.
4. Steam piping not insulated.
1. Float valve on the Low Water Control is stuck in the down
position.
2. Solenoid valve is not operating.
3. Check for defective mercury tube on the Low Water Control if
boiler has a motor and pump assembly.
Boiler continuously blows power fuses:
Pressure increases beyond the preset limits causing
safety valve to blow:
1. External fusing is not sized properly. Correct sizing is next size
larger than boiler rating.
2. Check lines between element and contactors with an ammeter
for uniform readings.
3. Check for evidence of charring which indicates loose connec-
tions.
4. A short circuit exists in the boiler.
1. Check bellows in the pressure control.
2. Check for clogged syphon tube.
3. Contactor points have fused.
4. Check pressure control setting against safety valve rating.
Manual reset button needs constant resetting (for
states requiring reset buttons only):
Boiler does not fill with water automatically or does not
maintain constant pressure:
1. Check water supply line for closed valves.
2. Check power fusing.
1. Boiler is not level; relocate if necessary.
© 2010 Chromalox, Inc.
CONTACTOR FAILS TO ENERGIZE
If the contactor fails to energize, check for blown fuses in
the control circuit. If the fuses are not blown, check the contac-
tor holding coil. The holding coil can be checked by jumpering
Terminal L1 of the line and Terminal No. 4 (coil lead) on the
contactor. See Figure 1.
A. If the contactor fails to energize, then the coil is defective.
B. If the contactor energizes, it is an indication of failure in
either the Pressure Control or in the McDonnell-Miller three
wire mercury switch.
Figure 1
Since the Pressure Control and the three wire mercury switch
are wired in series, they can be checked one at a time by placing
a jumper across each control. If the mercury switch or Pressure
Control fail to energize, check the McDonnell-Miller controls by
jumpering Terminals 5 and 6. See Figure 2.
At this point, the contactor should energize unless there is an
open wire in the control circuit.
Figure 2 — Low Water Cut-Off Junction Box
PRESSURE CONTROL — Malfunctions in the pressure control
can be mechanical or electrical.
Pressure
Control
Setting
The bellows should be removed and the small orifice at the
bottom cleaned out. The bellows must be replaced if it is punc-
tured. The syphon tubing should also be cleaned by steam while
the control is removed; it will be necessary to join the two loose
leads in order to activate the boiler. See Figure 3.
Differential
Control
Setting
The electrical controls should be checked by referring to the
Contactors, Elements and Voltages section.
Bellows
NOTE: If control is purchased locally, remove #8-32 orifice
screw.
Syphon
Tube
Figure 3 — Pressure Control
LOW WATER CUT-OFF — Like the pressure control, difficul-
ties can be broken down into the mechanical and electrical
groups.
assure that it is properly seated. If the valve seat is scarred or
defective, the entire valve seat must be replaced. Also, if the float
valve is in the down or “off” position, it may be punctured or
encrusted with dirt and the unit must be disassembled.
The mechanical difficulties can be corrected on the high pres-
sure 100 psig motor and pump units in the following manner:
1. Remove the cover and test the free movement of the float
valve. If the float valve is in the off or down position, then the
float is either punctured or dirt and sediment is encrusted in the
float chamber. Both of these problems will involve disassem-
bly of the float chamber.
2. Check the electrical contacts to determine if they are defective.
Defective mercury tube contacts will cause the boiler to fill high-
er than normal. This occurrence will require replacement of the
mercury tube.
On all McDonnell-Miller cut-offs, restrictions in the equalizer
column can cause burnt out elements. The cause will appear to be
a low water condition. Regular blowdown procedures on the
equalizer column as well as the boiler will prevent this occur-
rence. Correction of the problem can be made by both removing
the plug from the side of the column and opening the Low Water
Cut-Off blowdown valves. A snake should be used to clean the
vertical and horizontal columns.
The electrical trouble shooting should be checked by referring
to the Contactors, Elements and Voltages section.
On low pressure feed units, the mechanical test is best made
by cleaning the valve seat beneath the float valve linkage to
WATER FEED MECHANISMS — A common problem in this
area is boiler flooding, which may be caused by a defective float
or solenoid.
A defective check valve can cause the pump motor to run
continuously or cause loss of water pressure. If the pipe between
the check valve and the water supply is hot, boiler water is back-
ing up through the check valve and the check valve must be
replaced. A defective check valve can also prevent water from
entering the boiler.
The Low Water Cut-Off must be disassembled to check the
float valve. The solenoid can be isolated by disconnecting the
union after the solenoid and energizing and de-energizing the
solenoid. If water comes out continuously or does not come out
at all, then the solenoid is defective.
The coupling between the motor and pump may be loose; the
entire pump must be replaced if the coupling is excessively worn.
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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