Excessive current at Grundfos UPS2 heating pump start up

[scottyboy235]

Chaps,

I am after some advice regarding a brand new Grundfos UPS2 pump which appears to be drawing excessive current at start up. It is being used in a domestic gravity hot water/pumped heating system and replaced an old Selectric pump which had been in use for > 15 years in the same installation without any problems.

When the UPS2 starts up it causes the relay contacts on the heating programmer to weld themselves together. The programmer contacts have a rating of 3A resistive, 1A inductive which is way more that the 0.42A drawn by the pump when it is running. Three programmers have all gone to meet their maker with the same fault

Now the only other thing which has changed in the installation is the fitting of a one way valve on the inlet side of the pump.

Now I am worried that the one way valve may be contributing/creating this problem -> possibly by creating a temporary flow restriction at pump start up i.e. the valve remains closed until the pump has forced enough water through the system to open it up.

Anyone else had experience of a weird problem like this?

 

[Dotty]

re: Excessive current at Grundfos UPS2 heating pump start up

It's the starting surge current. Use the relay to switch a contactor and feed the pump through that.

 

[Jimbob]

re: Excessive current at Grundfos UPS2 heating pump start up

Did the pump come with a suppressor lead? I think that cures the overdraw issues in some cases

 

[Reg Man]

re: Excessive current at Grundfos UPS2 heating pump start up

Not very up to date on new pumps, but thought all new pumps came with this lead.

 

[mountainman]

re: Excessive current at Grundfos UPS2 heating pump start up

Not very up to date on new pumps, but thought all new pumps came with this lead.

Not all of them.

 

[scottyboy235]

re: Excessive current at Grundfos UPS2 heating pump start up

Great response chaps, couldn't have hoped for more. Thanks especially to Jimbob

I got straight onto Grundfos and guess what? They eventually admitted that there is a known problem with this pump which can be cured by using the suppressor lead. When I heard this I said 'what lead ...it didn't come with one'.

Anyway after trying to convince me to go back to the supplier and buy the lead I asked outright for them to supply me with a lead free of charge, delivered direct to site and to foot the bill for all the excess parts/labour this problem has caused - and yes they have agreed!

Top notch result, hope it turns out be true. I would say well done Grundfos for good customer service but I had to ask for everything, no information was volunteered.

 

[scottyboy235]

Update - I now have the cable, it was delivered several days after my initial call (ggrrrhh)
Good news is that it does indeed appear to work, same installation, new programmer (same model), same pump and no faults. Thank god for that.


For anyone who wants to know, Grundfos motor catalogues state that the initial current surge on startup can be up to 10 x average current and it is load independent. For this type of pump the average running current is 0.42A (max), so worst case thats 4.2A !


The cable they supply is called a suppressor or NTC cable ...and no you will not find any mention of its part number in the catalogue database. Anyone would think that this nice new energy efficient pump has a design flaw that needs to be kept a secret. On the plus side I was told the pump electronics have been re-designed so the cable is no longer required. Unfortunately I couldn't find out what the new part number is - I tried but lost the will to live in trying to do so.


The damages claim is still unsettled - I tried to talk to the Grundfos organ grinder but was told by the monkey that he is snowed under - probably with damage claims I would guess. Think I am in for a long wait.

 

[scottyboy235]

Update - I now have a nice fat cheque from Grundfos to cover the damage caused by the 'faulty' pump. Pity I didn't claim for my time plus all the aggravation it caused.

On a side note - I had to keep chasing them about this claim, even although they had admitted full liability.