Problems with Grundfos shower pump

crótach

Hi folks,

Dunno if you've come across anything like this, but any help would be appreciated.

We just had a pump installed to supply the two bathrooms in the house and it's working great, except that sometimes when you use a hot water tap elsewhere in the house, that isn't plumbed to the pump, it starts pulsing. It keeps going on and off in one second intervals and has to be switched off.

It's scary, I didn't want to see for how long this can last because I'd imagine it's damaging the pump. The plumber doesn't seem to know what it could be but he's coming over next week to check.

Grundfos suggested that it might be air in the system, but we've had a flange fitted to ensure an air-free supply of hot water and we've done everything they've suggested to get rid of possible air in the pipes. (running hot taps everywhere in the house)

It's early days still but I'm not feeling confident that the plumber will know what to do and was hoping that someone might be able to point us in the right direction.

Thanks!

Joey the lips

You have a flange fitted and thats correct. Is the pump connect to the flange itself or is it on a T when it comes out of the flange and feeding the whole house.

Can you take any pictures.

crótach

The pump is fitted directly to the flange, as far as I can tell it's exactly as in the instructions.

I took some photos of the installation and of the instruction sheet as well. Hope it helps!

Joey the lips

Now that is a strange one. I do not know myself what it can be. Sorry.

yoshytoshy

It sounds like it's the head of water decreasing thats activating the pump.

If that is the case ,I can't see anyway around the problem other than some sort of non-return valve on the shower feed ,to stop the pump picking up any change.

Joey the lips

yoshytoshy wrote: »

It sounds like it's the head of water decreasing thats activating the pump.

If that is the case ,I can't see anyway around the problem other than some sort of non-return valve on the shower feed ,to stop the pump picking up any change.

That should be an easy one to do. Its all done on pex. its actually a recoimendation that modern plant use to advise with its monsoon pumps. However since they started advising on surrey/warwick flanges this problem was gone.....until now.:(

yoshytoshy

Joey the lips wrote: »

That should be an easy one to do. Its all done on pex. its actually a recoimendation that modern plant use to advise with its monsoon pumps. However since they started advising on surrey/warwick flanges this problem was gone.....until now.:(

I've never heard of this problem with a surrey flange either:(

I didn't realise grundfos did pumps for showers ,I thought it was just pumps for unvented water systems.

Joey the lips

yoshytoshy wrote: »

I've never heard of this problem with a surrey flange either:(

I didn't realise grundfos did pumps for showers ,I thought it was just pumps for unvented water systems.

Nahh they took over salamander as far as i know. They are doing shower pumps at least 2 years... They have improved the pump and remoddeled it. You should remember salamander from your suppliers.

Yes it is a weird problem...not to scare the op..... But what ever it is. Grundfos have an excellent service record and I cannot see anything wrong with the connection so it might require a call out from grundfos.

crótach

Thanks lads, I'll give Grundfos a shout on monday.

I did check the instructions and it says a possible problem for the "pulsing pump" is a faulty non-return valve. We definitely don't have one installed.

Just out of curiosity, where should it be fitted? On to one of the pump inlets/outlets, or somewhere else?

Joey the lips

crótach wrote: »

Thanks lads, I'll give Grundfos a shout on monday.

I did check the instructions and it says a possible problem for the "pulsing pump" is a faulty non-return valve. We definitely don't have one installed.

Just out of curiosity, where should it be fitted? On to one of the pump inlets/outlets, or somewhere else?

Just before the pump inlets. NOT OUTLETS VERY IMPORTANT.AND MUST BE ON THE INLET IN THE RIGHT DIRECTION TO ALLOW FLOW IN.

crótach

Ah, grand so. Should I get two non-return valves, one for hot and one for cold?

cnocbui

Pressurise the whole house from the pump!

Joey the lips

crótach wrote: »

Ah, grand so. Should I get two non-return valves, one for hot and one for cold?

Ring the plumber let the plumber pick 2 up or if you want you can.

crótach

Lads, me again. I picked up two non-return valves at the weekend, the plumber should be in tomorrow. But I just went through the pump's manual and it says:

" Do not fit non-return valves in the suction line to the pump. Make sure that the pump can vent back to the supply tank."

Not sure what to do now

yoshytoshy

Crotach ,if theres a plumber going over to you ,let him work away at it.
Somethings just need a hands on ,to fix them.