Grundfos CR Installation And Operating Instruction Manual

23
Problem Possible cause Remedy
Pump cycles too much 1.
Pressure switch is not
properly adjusted or is
defective.
Check pressure setting on switch and operation. Check voltage
across closed contacts. Readjust switch or replace if defective.
2.
Level control is not properly
adjusted or is defective.
Check setting and operation. Readjust setting (refer to level control
manufacturer’s data). Replace if defective.
3.
Insufficient air charging or
leaking tank or piping.
Pump air into tank or diaphragm chamber. Check diaphragm for
leak. Check tank and piping for leaks with soap and water solution.
Check air to water volume. Repair as necessary.
4. Tank is too small.
Check tank size and air volume in tank. Tank volume should be
approximately 10 gallons for each gpm of pump capacity. The
normal air volume is 2/3 of the total tank volume at the pump cut-in
pressure. Replace tank with one of correct size.
5. Pump is oversized.
Install pressure gauges on or near pump suction and discharge
ports. Start and run pump under normal conditions, record gauge
readings. Convert psi to feet (Measured psi x 2.31 ft/psi = ____ ft)
Refer to the specific pump curve for that model, ensure that total
head is sufficient to limit pump delivery within its design flow range.
Throttle pump discharge flow if necessary.
Fuses blow or circuit breakers or
overload relays trip
1. Tank is too small.
Check voltage at starter panel and motor. If voltage varies more
than –10 % / + 10 %, contact power company. Check wire sizing.
2. Motor overloads are set too low.
Cycle pump and measure amperage. Increase heater size or
adjust trip setting to a maximum of motor nameplate (full load)
current.
3.
Three-phased current is
imbalanced.
Check current draw on each lead to the motor. Must be within
–5 % / + 5 %. If not, check motor and wiring. Rotating all leads may
eliminate this problem.
4. Motor is shorted or grounded.
Turn off power and disconnect wiring. Measure the lead-to-lead
resistance with an ohmmeter (RX-1). Measure lead-to-ground
values with an ohmmeter (RX-100K) or a megaohm meter. Record
values. If an open or grounded winding is found, remove the motor,
repair and/or replace.
5. Wiring or connections are faulty.
Check proper wiring and loose terminals. Tighten loose terminals.
Replace damaged wire.
6. Pump is bound.
Turn off power and manually rotate pump shaft. If shaft does not
rotate easily, check coupling setting and adjust as necessary. If
shaft rotation is still tight, remove pump and inspect. Disassemble
and repair.
7.
Defective capacitor
(single-phase motors).
Turn off power and discharge capacitor. Check with ohmmeter
(RX-100K). When the meter is connected to the capacitor, the
needle should jump towards 0 ohms and slowly drift back to infinity
(h). Replace if defective.
8.
Motor overloads at higher ambient
temperature than motor.
Use a thermometer to check the ambient temperature near the
overloads and motor. Record these values. If ambient temperature
at motor is lower than at overloads, especially where temperature
at overloads is above +104 °F (+40 °C), ambient-compensated
heaters should replace standard heaters.
Grundfos.bk Page 23 Wednesday, March 18, 2009 10:38 AM

Grundfos CR Specifications

General

Impeller Material	Stainless steel
Type	Centrifugal Pump
Temperature Range	+120 °C
Material	Stainless Steel
Applications	Water supply, pressure boosting, cooling systems
Connections	Flanged