Noisy pump -- what's this noise??

[adamson342]

Dear all,

Please could anyone suggest what might be making my central heating pump rattle like this? I am very happy to supply more details if required.

https://www.youtube.com/watch?v=_FLB_cfQXBs&list=UUw0AU4hFL2wwbKhTxG1c-fg

Best,
Sam

 

[Scarum]

Sounds like a bearing, I take it the pump is pumping around the system? In which case it might continue working for months to come (noisily!)

 

[adamson342]

Hi Scarum, thanks. Yes, seems to be pumping round the system as far as I can tell. Would a duff bearing mean a complete replacement of the pump? Any idea what cost would be reasonable?

Thanks,
Sam

 

[TCCHeating]

You can replace just the head. There are 4 allen bolts to remove once the water is isolated. Any modern grundfos head will fit that body.

 

[ScottishGasMan]

Yea, dodgey bearing or impellor, did also sound like there was a noticable hint of air in the pump/pipes too, is it an open system? (feed and expansion tnak probably in loft)

Easy job to swap for another pump/pump head. THe one you have would typically be replaced with something like this http://www.anchorpumps.com/grundfos...ZUkC8HJqYrHqs_4kM_izBySCFY5OnW19nMaAv-W8P8HAQ

although shop about as this is just the first pic I seen on google. You could replace with a much cheaper pump such as a WILO but the grundfos pumps are the best IMO.

Problem is you can not use the isolating valves at the sides to simply isolate the pump and change over as they look like balofix valves which have a 99% chance of sprining a leak when touched so would be a drain down.

 

[adamson342]

Got it, thanks.

You're right it's an open system with a water tank and does have a problem of having air in the system (apparently the tanks aren't high enough above the boiler -- I'm in a flat).

So just one question -- could this noise be air alone or does the pump definitely need replacing?

Ta,
S

 

[ScottishGasMan]

Some times occasionally when grundfos heads have air in the mthey will give off a rattle until all the air has cleared so its hard to tell, there will be a speed selector on the pump ranging from power I to power III. what is it set at?

Does sound like the bearing will be knacked tho, especially the longer its been making the noise for. Up to you whether to chance it failing in winter or replace now, but id strongly recommend dealing with the air ingress issue at the same time so as not to wear out the new pump prematurely.

 

[adamson342]

Thanks this is all really helpful.

It's currently set to 3 -- what does that suggest?

S

 

[TCCHeating]

Thanks this is all really helpful.

It's currently set to 3 -- what does that suggest?

S

That seems quite high for a flat. Try it at 2 and see if that helps

 

[Scarum]

3 is fast, 1 is slow. A fast pump can draw air in to the system. For a flat I would have thought 3 would be OTT, try 2.

 

[ScottishGasMan]

Yep, as above, try it on setting 2 then one to see if over time the air problems reduce and if it helps the noise.

 

[adamson342]

Great, thanks for this. I will give it a try and let you know how things go.

Thanks again

S