Circulation Pump - Navien NCB500-2S/37K Service Manual

4.7.13 Circulation Pump

Item
Function
Fault
Symptoms
Error codes
Diagnostics
Testing/inspection
information
52 System Details
1. Provides internal or external water circulation.
2. Internal circulation minimises the effects of temperature fluctuations. External circulation quickly
delivers hot water to taps and results in water conservation.
Unable to detect or measure water flow.
1. Water inside the boiler system freezes.
2. Water temperature fluctuations when the boiler is set to internal recirculation.
3. Hot water takes a long time to be available at taps when the boiler is set to external recirculation.
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1. Visual inspection: Check the circulation pump connection wire.
2. Check the water filter for obstructions.
3. Voltage test: Test the voltage meets the specifications shown below.
4. Free a jammed pump rotor.
If a pump is not moving it may be a build-up of debris in the pump which will prevent the internal
rotor from turning. The pump has a built-in mechanism which will attempt to turn the pump when this
happens. The pump can often be heard clicking repeatedly. This is the noise a pump will make when
trying to free itself. If the pump is too clogged up to free itself the internal rotor may have to be turned
manually. In the centre of the pump head there is a hole. Insert a long shank CROSS HEAD screwdriver
and locate the tip into the rotor shaft. The shaft must be pushed in hard and then turned in order for it
to engage it onto the rotor. Only then will the user be able to turn and free the rotor.
YELLOW-WHITE
ON: AC 230 V
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OFF: 0 V
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Description