Grundfos pump noisy and getting very hot

[M Mannas]

Hi all,


Please forgive my ignorance. I am trying to learn about my central heating system but need help.

I have a very noisy Grundfos pump. I have lived at this house for about three years now but over the past few days it has suddenly become very noisy. It sounds as if the pump is rumbling or grinding. My wife described it as the sound the kettle makes if there is not enough water in it. Every so often I am getting a loud popping noise too.

I touched the pump and its really hot - too hot to keep my hand on it while the water is heating. Having not touched it on a regular basis I don't know if its supposed to be this hot.

Any help would be greatly appreciated.

Kind Regards

Matt Mannas

 

[vulcancontinental]

Turn the hot water and heating off while you deal with the problem.

Have you got two tanks in the loft? If you have, go to the small one and make sure water is in there - not just some water in the tank but that the level is above the outlet (a small pipe usually an inch or so up from the base on one side. Sometimes it is drilled through the bottom of the tank).

While you're there work the ballvalve up and down to make sure it's not stuck in the up or off position.

See what happens

 

[M Mannas]

Thanks for your help its really appreciated.

No tanks in the loft. I think its a pressurized system. I did notice that the pressure dropped very low (almost to 0) while i was checking and have since adjusted to above 1 again. Not sure why it dropped so suddenly. I have turned hot water back on and now no noise.

Can you tell me how warm/hot the pump should get? Is this a sign of the pump on the way out?

Thanks again.

Matt

 

[vulcancontinental]

If you were running it with no water in it or it got jammed it will get VERY hot. Normally it is as hot or a little hotter than the water running through it. It will cool down.

I was told the other week that the test on Grunfos pumps or any pump sold in Germany is for it to operate as a normal after it has been forced to a stop for 72 hours!! I had no idea of this. If it's working now and quiet let it continue. I've always been amazed at the punishment Grunfos pumps will take and still perform.

Apparently the UK paramenters for a domestic heating pump do not include any stipulations about how long it should remained stalled and work afterward, simply that it is electrically safe and turn

Possibly somebody else here will know more and better.

 

[45yearsagasman]

I read somewhere yhat the surface temp of a domestic pump can be 125C.If your pump is now quiet and circulating ok leave well alone.Make sure that it is not covered up by anything and that the fuse rating for your system is correct.

 

[daneski88]

Keep an eye on that pressure - if it drops again the make sure you bleed the system (including the pump), repressurise and keep us appraised.

 

[M Mannas]

Thanks all for your help. Its still hot and have made sure the pump is well clear to let the heat escape. The pressure is dropping slightly so will keep an eye on this if it continues to do so I think I might ask a plumber to bleed the system.
Matt

 

[DeltaT]

Matt, ensure you get a well qualified time-served Plumber to have a look at it. Someone that knows how to 'clean the can' on your circulator.

 

[M Mannas]

What do you mean when you say "Clean the can" on the circulator?

Matt

 

[penfold46]

Matt, ensure you get a well qualified time-served Plumber to have a look at it. Someone that knows how to 'clean the can' on your circulator.

Clean the Jockey tank? Vent the pump? Most Scots I know 'Neck a can' before getting out of bed.

As a plumber, Id also like to know. You Scots do confuse the likes of a Londoner