Bell & Gossett DN0136C Domestic Pump Vacuum Heating Units Series VCL - Manual (Page 11)

TROUBLESHOOTING PROCEDURES – V ACUUM PRODUCER
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 opera-
tion.
6. Wiring to control cabinet is incorrect or connections are
loose.
7. The system has vacuum and vacuum switches are open.
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. System flow or leaks prevent the unit from developing
design vacuum. Vacuum system must be tight.
3. System is drawing vacuum greater than the vapor pressure
of a liquid – the liquid is being boiled and then condensed
in the vacuum unit.
4. Holes in the nozzle plate are plugged and the system will
not develop vacuum. Inspect and clean nozzle plates.
5. Incorrect liquid level in the hurling chamber (flooded or
empty).
6. Improper vacuum switch adjustment or selector switch in
“continous” position.
7. Hurling water level incorrect.
SYSTEM OVERFLOWS
1. System may be normal. Cooling water is required to lower
vapor pressure of hurling water to be able to draw deep
vacuum.
2. Temperature limit switch is set lower than required and
adds unnecessary water.
3. The design vacuum is greater than the vapor pressure of a
liquid within the system. The liquid is being boiled from the
system and condensed in the hurling chamber.
4. Temperature limit switch is wired incorrectly.
5. Float switch is improperly adjusted. Remove float switch
cover plate and readjust the cam activating the electrical
switch.
THE SYSTEM STARTS AND STOPS RAPIDLY
1. Pumping against a small closed system. Add vacuum stor-
age tank or reset vacuum switches.
2. Closed or partially closed valve in air line.
3. Pipe friction losses in suction line cause higher vacuum
close to vacuum producer. Relocate vacuum lines to point
which senses true system vacuum.
BOTH PUMPS RUN
1. Improper vacuum switch adjustment. Readjust lead
vacuum switch to make and break at deeper vacuums than
the lag switch.
TROUBLESHOOTING PROCEDURES – CONDENSA TE PUMP
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. Insufficient condensate has accumulated to actuate float
switch.
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. 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.
4. A valve in the discharge line is closed or throttled too
tightly. Check valve is installed backwards.
5. The impeller eye is clogged.
6. Pump is too small for system.
CONDENSA TE 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.
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