Grundfos Scala 2

FixdePitchmark

Had a long night - water pump cutting in every 2 minutes. The cut in time has been reducing and reducing over the last few weeks - all started with the loss of water one day and power another by ESB / DCC.

Ended up removing the pump - checking NRVs - and re-priming - this put the cut in time to about 15 mins. But still a problem.

I'm not useless - but realised in all my messing I dropped the internal pressure vessel in the pump by draining it by error.

Could someone help me out and tell me what pressure I should pump this up and how. - and is there anything I should buy to get a good pressure reading on this - is there a pluming pump ? (would like to have it for next time)

Thanks - posted here as Christmas and not a chance of getting a plumber too easy at present.

John.G

Saw somewhere that the precharge pressure should be 70% of the required outlet pressure so if your outlet pressure is 3 bar, pump to 2.1 bar etc.
I expect you should see a dust cap on the schrader valve (like a car tyre type) and you can pump it up with anything you like as long as it or you have a pressure gauge, I bought a fairly cheap electric one in Argos years ago for my cars tyres and the gauge is quite accurate, I have pre charged numerous neighbours heating expansion vessels with it.

FixdePitchmark

John.G wrote: »

Saw somewhere that the precharge pressure should be 70% of the required outlet pressure so if your outlet pressure is 3 bar, pump to 2.1 bar etc.
I expect you should see a dust cap on the schrader valve (like a car tyre type) and you can pump it up with anything you like as long as it or you have a pressure gauge, I bought a fairly cheap electric one in Argos years ago for my cars tyres and the gauge is quite accurate, I have pre charged numerous neighbours heating expansion vessels with it.

Thanks a million.

I think with everything that went wrong . My heating expansion vessel also needs to be charged.

I'll buy one today . I assume I'll have to de-pressurise the pump first ?. Otherwise your acting against stored pressure?

John.G

Yes, you also have to drain the heating system to pre charge the expansion vessel to 1 bar then fill it to 1.5 bar with a cold system.

FixdePitchmark

John.G wrote: »

Yes, you also have to drain the heating system to pre charge the expansion vessel to 1 bar then fill it to 1.5 bar with a cold system.

Thanks John - got a small digital one in Halfords - and the pressure was zero :eek: - I think this may solve all my problems.

Not sure I have confidence to drain hot water system - as fairly complex and tied in with rads and underfloor heating etc. I don't think the closed system was impacted on.

But thanks a million for tips.

John.G

Very good, what you could do with the heating system is to wait until fully hot, then if pressure is still too low just top up by 0.3/0.5 bar but not to greater than 2 bar.