Pump very hot & no CH

[ashR]

Hi All,

Looking for some advice to see if there's a simple (or at least temporary) solution here.

I have a gravity fed system with two loft tanks and a Potterton 40e boiler. The pump (Grundfos) is red hot when running. There is hot water (though seems not as hot as it used to) but no heat to any radiator.

The pump is spinning with both pipes either side heating up. The flow pipe to the nearest radiator from the pump gets hot, but not the return or any other rad pipe. The noise when running made it clear there was lots of air in the system and bleeding the rads and pump has killed the noise, but not the issue. There's plenty of water in the loft tank.

I've tried different combinations of rads on/off and switching the three way valve to manual.

Two observations that might help. There is a build up of white scale / crust on the valve above the pump. Also, I opened the lower drain point to check for air and after the first 2-3 seconds the water only drips out, barely a trickle.

Any help from the experts is much appreciated 🙂


Ash

 

[chris watkins]

New pump time most likely.

 

[joni os]

Plus 1 for pump and check for blockage in cold feed so new pump doesn't get ruined.

 

[ashR]

Thank you both. Sounds like new pump time it is.