Noisy Grundfos

[danhamman]

At certain points during the day, our pump gets VERY noisy. Sounds like the house is about to explode. Can happen at 4pm or 4am, doesn't matter if heating is switched on or off.
I recall thew pump was only installed within the last two years.
Also it gets very very hot whilst noisy.
I've checked water tanks in the loft and they are both at a good level.
I've tried bleeding one or two radiators.
Cause? Solution?
Thanks

 

[CBW]

Is it definitely the pump, and not a motorised valve? You mention the heating, but not the hot water - is this on permanently?

Also it gets very very hot whilst noisy.

What gets hot then pump or radiators?

 

[danhamman]

Hot water comes on for 30 mins in the morning, 30 mins in the afternoon - it's not neccessarily switched on when the pump is noisy (eg. at 1am this morning)
How would i be able to tell if it was the motorised valve? Signs?
Thanks

 

[danhamman]

Both get hot.
Radiators work fine. Water works fine.

Pump is scorching hot whilst being noisy, sounds like someone is drilling.

 

[ianmcd]

Hot water comes on for 30 mins in the morning, 30 mins in the afternoon - it's not neccessarily switched on when the pump is noisy (eg. at 1am this morning)
How would i be able to tell if it was the motorised valve? Signs?
Thanks

The motorised valves have a lever at the side for manually opening the valve , with demand switched off this lever should slide across but with some resistance, with the demand switched on the levers should slide across with no resistance