Bell & Gossett DN0129D Series CMU - Manual (Page 7)

7
TROUBLESHOOTING PROCEDURES
(ITEMS MARKED WITH * FOR CMU ONLY)
All units ar e thoroughly tested at the factory before shipment.
They should operate satisfactorily without further adjustment if
properly installed and providing they have not been damaged
by rough handling in transit. If system or unit performance is
not satisfactory, refer to the following check list.
PUMP WILL NOT ST ART
1. The power supply has been interrupted, disconnect switch
is open or selector switch is improperly positioned.
2. Incorrect voltage for motor. Check voltage and wiring with
motor characteristics.
3. Incorrect starter coil for power supply.
4. The overload relays in the starter have tripped out and
must be reset. Ambient temperature may be too high.
5. Check pump controls or other controls for proper operation.
6. Wiring to control cabinet is incorrect or connections are
loose.
7. The strainer is dirty thus retarding flow. Clean periodically.
*8. Boiler is full or boiler control switch is defective.
*9. The low water cut-off float switch is open due to low water,
incorrect adjustment or failure.
PUMP RUNS CONTINUOUSL Y
1. Pump is running backward. Rotation of three phase
motors may be corrected by interchanging any two of the
three wires. Rotation should be clockwise looking down on
motor.
2. Steam traps are blowing through causing condensate to
return at excessive temperatures. This may reduce the
capacity of pump below its rating, depending on the unit
and type of pump furnished. Traps should be repaired or
replaced.
*3. Pump discharge pressure is less than operating pressure
of the boiler.
4. The total required pressure at the pump discharge is
greater than the pressure for which the pump was
designed. Check the total pressure which includes atmo-
spheric pressure, the friction head and the static head.
5. A valve in the discharge line is closed or throttled too tightly.
Check valve is installed backwards.
6. The impeller eye is clogged.
7. Pump is too small for the system.
PUMP IS NOISY
1. The pump is working against a lower pressure than
designed for. While pump is discharging, adjust plug cock
in discharge line until pressure at pump approaches pump
rated pressure.
2. Excessive condensate temperature. Correct system condi-
tions. However, this applies to certain units only; others are
designed to handle boiling water.
3. Magnetic hum or bearing noise in motor. Consult motor
manufacturer’s authorized service station nearest unit
location.
4. Starter chatters. Trouble is caused by low line voltage, poor
connections, defective starter coil, or burned contacts.
5. Pump is running backward. Rotation of three phase
motors may be charged by interchanging any two of the
three wires.
THE SYSTEM IS NOISY
1. Banging in the steam mains is usually caused by “implod-
ing” in condensate lying in low points in lines. These
pockets can be eliminated by dripping low points, prop-
erly supporting the pipe, or by increasing the pitch of the
lines.
2. Improper dripping of the steam mains and risers; where
there is a rise in the steam main, or where it branches off
into a riser, a drip trap must be installed to the drain line.
3. The piping is too small to drain properly.
4. A defective trap is holding condensate in steam supply
line.
*5. Defective check valve permits steam to vent thru pump
into the boiler feed tank.
6. A priming boiler is discharging water with the steam.
Consult boiler manufacturer.
EXCESSIVE W ATER OVERFLOW FROM UNIT
1. Receiver sized too small to accommodate system surges.
*2. Water make-up valve open or float switch set too high.
*3. Water make-up valve leaks.