Pump makes screaching noise for 5 seconds when hotwater is called.

[imran999]

I replaced a faulty grundfos pump with a new grundfos central heating pump, and all seems to be ok, in terms of function etc.
however, one issue i have is that when hot water is called for (alone) then their is a screaching noise coming from pump/3 way/or other which lasts for around a few seconds and then goes.
Perhaps coincidently,...the lights on the pump dont come on for a few seconds and this is when the screaching is occuring.

This only happens when hot water is called and not for central heating.

Is this possibly air in the system? If so, how do i get it out?
Or is their some sort of delay on the pump causing issues?

Note, i am not too technical with plumbing.

 

[Darren Jackson]

It could be the 3 way valve that has just about had it. And the motor or gears are worn. It needs to activate the microswitch to turn on the pump. So it is probably the noise of the 3way motor/gears struggling; and eventually it gets there & operates the microswitch and then the pump comes on and the noise then goes away.

 

[imran999]

It could be the 3 way valve that has just about had it. And the motor or gears are worn. It needs to activate the microswitch to turn on the pump. So it is probably the noise of the 3way motor/gears struggling; and eventually it gets there & operates the microswitch and then the pump comes on and the noise then goes away.

Sounds like you may be right...the noise is coming from the 3 way before the pump kicks in.

Its a old style 3 way which you can't replace just the head....wonder if bgas will cover it under my boiler repair cover.....no doubt they will find some excuse not to cover.