Chromalox PQ402-6 User Manual

PQ402-6

161-049460-001

FEBRUARY, 1999

4 CES

SERVICE MANUAL

(Supersedes PQ402-5)

Chromalox Electric

Steam Boilers

© 2010 Chromalox, Inc.

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 prop­erly.

5. Elements and/or contactors faulty.

6. Mercury tube in Low Water Control has cracked and mercury

has escaped.

Boiler takes too long to reach operating pressure or
does not maintain desired pressure:

1. Check amperage on each supply leg of power harness. Reading
should correspond to a rating of not less than 10% of rated boil­er amperage.
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.

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.

Boiler continuously blows power fuses:

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 connec­tions.

4. A short circuit exists in the boiler.

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.

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.

B. Check for defective solenoid valve.
C. Make sure pump is running with correct rotation.
D. Check impeller adjustment on turbine type pumps.

Boiler appears to be leaking from beneath the jacket:

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.

IMPORTANT: Leaking is a hazard, correct to prevent further

damage to other components.

Boiler overflows:

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.

Pressure increases beyond the preset limits causing
safety valve to blow:

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):

1. Boiler is not level; relocate if necessary.

The troubleshooting of Chromalox electric boilers can best be
placed into five major areas. These areas are: (1) fusing (2) con­tacts, elements and voltages (3) pressure control (4) low water cut­off (5) water feed mechanism.

WARNING: Hazard of Electric Shock and Thermal
Burns. These troubleshooting checks should only
be performed by qualified personnel after review

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.

TYPICAL MALFUNCTIONS & PROPER CORRECTION

Boiler syphons water:

1. Follow blowdown instructions.

Boiler with condensate system floods overnight:

1. Vacuum breaker is not operating.

Elements fail:

1. Low Water Cut-Off system has failed.

2. Lower equalizer tube on Low Water Cut-Off is clogged due to

lack of blowdown.

3. Contactor points have fused.

4. Lack of blowdown has allowed accumulation of foreign mate-

rial, which has smothered the heating elements.

5. Water softener is being used without an aeration device.

Motor runs too frequently and/or the boiler does not
maintain pressure:

1. Test check valve.

Motor runs continuously, but does not pump (CMB-10L
to CES-30):

1. Test flexible coupling on motor and pump.

2. Check water supply.

3. Blowdown valve partially open.

FUSING — The power fuses should be the first component of

equipment checked in any power failure. The fuses will be locat­ed in a panel near the boiler (or within the boiler on 72kW and
larger models).

Test each fuse with a test light or an ohmmeter. If the test
light glows or the ohmmeter reads infinite resistance, then the
fuse is defective and must be replaced. Fuses can be intermittent.
If all other boiler components appear to be in proper order,
replace all fuses with known good ones.

If a circuit breaker is used instead of fuses, check to see if all
breakers are in the “on” position. Reset if necessary.

If the fuses continue to blow or the circuit breakers continue
to trip off, then the internal circuits should be investigated for a
short circuit or ground.

CONTACTORS, ELEMENTS AND VOLTAGES

— The power supply voltage must be within ten percent of the
boiler voltage rating. The standard voltages are 120, 208, 240
and 480 volts; optional voltages are 190, 275, 380, 415 and 550
volts. All boilers rated at 275 volts and higher are supplied with a
separate control circuit of either 120, 208 or 240 volts.

To insure good current flow, it is important that all contacts
are mating properly. Contacts that appear burnt or charred must
be replaced.

DETAILED ANALYSIS