Wilo pump

[digger963]

Replaced Wilo pump had problem's with noise reduced the speed to 2 since then i have a problem with Hot water system when hot water is on pump cuts out and hot water vents into the expansion tank in the loft
Do i need to increase the pump speed because water is not moving quick enough The feed pipe to hot water is warm return pipe seams to be cold

 

[lightning]

Blocked cold feed
pump on right way round
are pump valves open

 

[digger963]

Pump is on correct way
Pump valves are open
Can I clear blockage by pressurising system i.e close valve on vent to tank

 

[oilman]

The impeller may not be attached to the shaft. A common problem with Wilo pumps. I will use only Grundfos.

 

[digger963]

Found blockage in cold infeed pipe problem now fixed
pump ok central heating working only problem with hot water