Since changing the pump the controller relays stick?!

So pleased I found this bulletin as I've just been experiencing the very same problem with my mothers central heating and its been doing my head in! Same thing; heating engineer came around to replace failed pump with Grundfos UPS2, shortly afterwards the original programmer (Danfoss LP2) failed in the on position. Thinking this was just coincidence I replaced the controller with identical and within days the same thing had happened e.g. failed on. As I'm an electrical engineer I carried out a full wiring check including tong testing the new pump - nothing showed up as wrong. I blagged a third programmer from the supplier claiming the first one was duff and same happened again. Now I realised this started when the new pump was fitted so I knew it had to be to do with that but couldn't prove it.
Nice to know there's a fix!

petit_pablo said:

For CC members read the thread about grundfos pump heads.

For the OP - the pump head will be causing the problem. Either fit another make of pump or go back to the merchant and ask for a suppresor lead for the grundfos UPS2 pump, or ring grundfos.

The timer will be gubbed also

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Have you got the link to the CC thread you talk about regarding Grundfos pump heads, I can't find it.

UPS2 should bring it up.


Either way. Cheap controls, especially Danfoss are affected. UPS2's were the cause. THey issued a lead to supplement existing stock then the newer ones were adapted to include it in the pump head.


Won't be fitting Grunnies now unless there is a damn good reason.

Grundfos will send you the leads for free, can't remember if they are paying for guffed components due to their lazy design.

Dan_Robinson said:

UPS2 should bring it up.


Either way. Cheap controls, especially Danfoss are affected. UPS2's were the cause. THey issued a lead to supplement existing stock then the newer ones were adapted to include it in the pump head.


Won't be fitting Grunnies now unless there is a damn good reason.

Grundfos will send you the leads for free, can't remember if they are paying for guffed components due to their lazy design.

Click to expand...

Danfos simply send them the number how many inits they get back ruined and Grunfos credit them.