Do I need a new pump?

[stevethejoiner]

Hi.
I have a GSHP and the underfloor heating loop is pumped by a Grunfos UPS 25-80-180.

Today I was near the grundfos pump and happened to touch it, it was so hot I would have seriously burnt my hand if I had not quickly removed it. The water in the heating circuit however was only at its usual warm temperature, ie pipes to and from the pump were only warm to touch as being heat pump system they never get really hot.
I removed the centre screw on the pump and steam escaped, that's how hot it was, and looked to see if the pump was stuck. Unfortunately I could not see a slot for putting a screw driver in to manually rotate the pump, there only seems to be tiny recess, maybe a small torx, its smaller than a pozi 2 and not a pozi 1 as I tried both. So I have no way to manually rotate to see if the pump is seized.
Then my son said, Dad its been hot like that for at least a year.

The thing is our heating has been fine, still is today, house gets lovely and warm but of course I do not know what the flow rate is around the underfloor pipework, but then I think the heat pump also has its own internal circulation pump the move the water around the heating circuit. But the installers must have fitted the Grundfos for a reason as it was with the heat pump when delivered 4 years ago and its shown on the install plumbing plan, maybe its more efficient with this 25-80-180 pump.
Ice Energy supplied and commissioned it, they are now no longer in business.

So I assume the pump is faulty. The pump is wired dired to the heat pump control panel, but I could disconnect the pump wiring so the pump is basically switched off, and possibly my heating will be just as efficient as it has always been, but the pump is there for a reason, and the heat pumps control panel will possibly know is not connected and cause error or fault codes and possibly shut down.
I do not think its safe to leave a pump that is this hot, it must also be wasting a lot of electrical energy and doing nothing.
So I should replace it, but can I use a cheaper pump? This Grundfos model looks to be £250 but I can see other makes for a lot less.

Thanks Steve.

 

[ianmcd]

when you were trying to free the pump with a screwdriver, you would have known if the shaft was turning as it would have made a grinding noise on the screwdriver head so it does indeed sound as if it is seized, the head on the pump shaft is neither a posidrive or a slot screw it is a daft wee shape and normally using a small slot screwdriver can get a grip, you might need to turn everything off and allow the pump to cool down before you can free it

 

[Gasguru]

Pictures needed...sounds as though it's the pump for the U/F heating circuit.
Normally a 4mm flat blade screwdriver will turn the shaft...but nothing will slot in properly as previously mentioned.
The whole point of heat pumps is low running temps...there's something up with that pump.

 

[stevethejoiner]

when you were trying to free the pump with a screwdriver, you would have known if the shaft was turning as it would have made a grinding noise on the screwdriver head so it does indeed sound as if it is seized, the head on the pump shaft is neither a posidrive or a slot screw it is a daft wee shape and normally using a small slot screwdriver can get a grip, you might need to turn everything off and allow the pump to cool down before you can free it

Thank you for the reply but there is no slot in the shaft for a screwdriver, I was wondering if it was a torx or small allen key?

 

[stevethejoiner]

Pictures needed...sounds as though it's the pump for the U/F heating circuit.
Normally a 4mm flat blade screwdriver will turn the shaft...but nothing will slot in properly as previously mentioned.
The whole point of heat pumps is low running temps...there's something up with that pump.

Thank you for the reply. I agree something wrong with the pump.
I have been looking at replacements, but this 25-80-180 is like £250 plus but other circulation pumps of the same make like the 15 50/60 130 are bout £60.
What is the difference?
Why does my UFH need a more expensive pump than a Rad heating system?
Especially as it looks like my house has heated just fine without this pump even working.

 

[Gasguru]

The pump fitting is 180mm compared to 130mm between valves.
The flow and pressure (head) is higher on the 25-80 pump. In theory it was sized for the U/F circuit.

 

[stevethejoiner]

The pump fitting is 180mm compared to 130mm between valves.
The flow and pressure (head) is higher on the 25-80 pump. In theory it was sized for the U/F circuit.

Thanks Gasguru.