Grundfos Alpha pump trouble. Do you know what's up with it??

[mikefromguildford]

Please don't say 'air in the system' Grundfos and a plumber have already said that. Bleeding/venting has not sorted it. I've got a Grundfos Alpha, 3yrs old, runs for a few hours each day. The pump works, pumps just fine (I have c/w + hot water)... but the flow is not constant. I can only describe it as a pulse. The green voltage light fades in and out with each pulse from the pump. There are no rattles/bangs. Just the normal sound of the pump, except it's pulsating. It's been like this for two weeks now - no change. Can't find anything similar complaints anywhere.... Please help!

 

[ollski]

Probably board has failed, what happens if you turn it up to a fixed speed setting?

 

[mikefromguildford]

Blimey, that's fast.

the 'dial' is almost fully clockwise. ie the thin point of the dial is pointing the the thick part of the indicator. i take this to be max?

I don't have a clue what i'm talking about. This may take a while.... Cheers

 

[mikefromguildford]

but to actually answer your question - turning the dial (while the pump is in use) does not have any effect

 

[mikefromguildford]

See profile picture for image of pump

 

[superdupergasman]

Thats how it controls its speed, pulses the power on and off is it not.... have heard them pulse before....just depends how long the off cycle is???

..... is it the alpha or the alpha plus...the plus model you can fix to a speed 1, 2 and 3 which is opposite the thickening line, you twist past the end.

 

[mikefromguildford]

Yes it's an Alpha +

Are you saying this is how the pump works? It may well have been pulsating for the past three years and I just haven't noticed...!

Is there a preferred setting for the alpha? I'm in a purpose built two bed flat built 2005, six radiators, combi boiler.

Any advice is welcome. I just don't want it to blow-up or become inefficient. Cheers.

 

[Gasguru]

..........combi boiler.

You sure you have a combi? Combi boilers require the pump to set at maximum speed for sufficient hot water performance. The pump should remain as standard in order for the boiler to remain safe and operate as intended. In addition they often have a manual or automatic bypass that would complicate the operation of the Alpha pump.

Only the very top end combis have modulating pumps.

 

[tonybhoy]

Judging by the photo the pump looks as though it is fitted external to the boiler.

 

[Saltire]

If the original combi pump has been replaced with the alpha that will be your problem..

 

[Gasguru]

Unlikley you'd even have the space to fit the Alpha in most combis anyway.

 

[mikefromguildford]

I've got an ideal ICOS HE15 gas fired fan-flued condensing boiler. The equipment has not been touched since day one. The Alpha is in the airing cupboard (near the Megaflow HE), the ICOS is in the kitchen. Hope this helps.... Thanks

 

[mikefromguildford]

someone on here must be able to shed some light on this..... HELP!

 

[breezer]

new pump?

 

[mikefromguildford]

any advances on 'new pump'? has anyone experienced this before?? I'm still getting hot water and heating..?