Hot Grundfos pump?

[ns3270]

I've just replaced my pump with a GRUNDFOS Super Selectric UPS 15-60 130 pump which was quite an easy job done in half an hour.

How hot is the pump supposed to get when the heating is on? It feels at least as hot as the radiators (which may be right as hot water is passing through it)? I don't remember checking how hot the old pump was.

I've vented the pump and checked all the radiators for air locks (there weren't any).
When I first switched the heating on, all the upstairs radiators were hot, half the downstairs ones were hot and half were cold. I turned off all the hot radiators and the cold ones heated up fine. Could there be an airlock in the pipework, and if so how do I get rid of it?

 

[seco services]

did you drain the system to change pump ?
if this is how you got the airlock and you've shut the hot rads to get the cold ones hot it should push the airlock out.
then you can re-balance the other rads back into the system

 

[ns3270]

I didn't have to drain the system to replace the pump as there were isolating valves just above and below the pump which I turned off before removing the old pump and on again after fitting the new one. I didn't think I should have to rebalance the radiators just changing the pump. There are 20 radiators in the house and I did upgrade the pump (which was exactly the same size) from the Grundfos 15-50 130 to the 15-60 130
for only £5 more.

 

[seco services]

as you say don't useally get any problems with airlocked rads the way you done it.
thats why i thought you had drained it.

but once the cold ones are hot try opening the closed ones and should all be ok.

 

[ns3270]

Thanks for that.
What about the temperature of the pump itself. Is it supposed to be quite hot when the heating is on?

 

[seco services]

like you said it has the heating water running through it so yes it will be hot and if it is circulating to rads it sounds all ok.

 

[JohnD]

about the same temp as the rads, and a bit hotter than the return pipe, is usual. If it is startlingly hotter than the pipes, it is probably jammed or blocked in some way (the water normally carries away any heat from the motor)

 

[ns3270]

The pump is hotter than the radiators but about the same temperature as the pipes either side of it.
It's a brand new Grundfos pump and I did rotate the shaft several times to ensure it was free.

 

[uknokianut]

Just a thought - if some rads aint getting hot , did you install the pump with the same flow direction as the one you took out ?

 

[ns3270]

The new pump was the same make and model as the old one, so I guess the flow direction would have been the same.

 

[Agile]

The new pump was the same make and model as the old one, so I guess the flow direction would have been the same.

The flow direction depends on which way the pump was fitted!

Nevertheless, I expect it was correct.

Tony

 

[muggles]

Further explanation of Tony's quite correct comment - the body of the pump (the bit you screw the nuts on to) determines the flow direction and has a flow direction arrow stamped into it. The new pump should have been fitted with the arrow pointing the same was as it was on the old one.

The pump will get hot in use, if it's the same temp as the pipes either side it's fine.

 

[lagunaglen]

Have you got the pump speed set correctly?
What was speed of old pump compared to speed of new one?

 

[uknokianut]

The new pump was the same make and model as the old one, so I guess the flow direction would have been the same.

The flow direction depends on which way the pump was fitted!

Nevertheless, I expect it was correct.

Tony

How can you say "Nevertheless, I expect it was correct." when there is a 50% chance it wasnt .

 

[ns3270]

Yes, the flow direction is the same on the new pump as it was on the old pump.
The old pump was the 15-50 130 and was set to speed 3.
The new pump is exactly the same size but is the 15-60 130, which means it is the higher rating (60,000 to 120,000 BTU as opposed to up to 60,000 BTU). I've also set the new pump at speed 3 but I thought I might be able to run it at speed 2 when it settles down.
I still have one downstairs radiator which is cold even though both end valves are fully open and there is no air lock in it.