Bell & Gossett DN0137D Domestic Pump Vacuum & Boiler Feed Unit Series VCMD - Manual (Page 6)

6
All units are 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, incor-
rect adjustment or failure of makeup system.
PUMP RUNS CONTINUOUSL Y
1. Pump is running backward. Rotation of three phase motor 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 atmospheric pressure, the friction head
and 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 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 conditions.
However, this applies to certain units only; others are designed to
handle boiling water.
3. The piping is too small to drain properly.
4. A defective trap is holding condensate in steam supply line.
5. Pump is running backward.
THE SYSTEM IS NOISY
1. Banging in the steam mains is usually caused by steam “imploding”
in condensate lying in low points in lines. These problems can be
eliminated by dripping low points, properly supporting the pipe, or
by increasing the pitch of the line.
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 in 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. Steam blowing thru a defective trap.
7. A priming boiler is discharging water with the steam. Consult boiler
manufacturer.
TROUBLE SHOOTING PROCEDURES - BOILER FEED SYSTEM
PUMP WILL NOT START
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. System has vacuum and vacuum switches are open.
8. Temperature limit switch open due to high condensate temperature.
9. Temperature limit switch improperly wired.
PUMP RUNS CONTINUOUSL Y
1. Pump is running backward. Rotation of three phase motor 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 vac-
uum. Vacuum system must be tight.
3. System is drawing vacuum greater than the vapor pressure of liquid
– the liquid is being boiled and then condensed in the vacuum unit.
4. Holes in the nozzle plate are plugged or worn and the system will
not develop vacuum. Inspect and clean nozzle plates.
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 unnec-
essary 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.
6. Boiler feed receiver sized too small to accommodate system
surges.
7. water make-up valve open or float switch set too high.
8. Water make-up valve leaks.
SYSTEM STARTS AND STOPS RAPIDLY
1. Pumping against a small closed system. Add vacuum storage tank
or reset vacuum switches.
BOTH PUMPS RUN
1. Improper vacuum switch adjustment. Readjust lead vacuum switch
to make and break at deeper vacuums than the lag switch. Refer to
manufacturers’ literature.
2. Low vacuum in system causing lag system switch to be closed.
TROUBLE SHOOTING PROCEDURES - V ACUUM PRODUCER