Lukewarm CH

robg47 · 22 Oct 2004

I have a 25 year old Ideal Standard conventional boiler and recently the pump went. I replaced the pump with a GRUNFOS 15/60 pump and the new pump appears to be working fine.
However, the pipes into/outof the boiler, all radiators and also hot water are never more than lukewarm even when the room thermostat and the boiler hot water thermostat are put at very high (max) settings.

The boiler turns itself off/on frequently even with the boiler stat on max. value with the result that the water pipes never get really hot.

Could the problem be due to air in the pipes or to a defective boiler stat? How could I tell?

kevplumb · 22 Oct 2004

1 read the post at the top
2 READ THE POST AT THE TOP

croydoncorgi · 22 Oct 2004

Are you sure you put the new pump the right way round???
Evidently the boiler is getting hot (so its internal thermostat is making it cycle on and off) but if there's little or no heat coming out of it, either the pump doesn't work (you say it does), there's a vealve shut somewhere or the pump's pumping the wrong way.

robg47 · 23 Oct 2004

The pump was put in with the word GRUNDFLOSS the right way up and with the direction arrow pointing upwards in a vertical manner (same as the previous pump). Also, the lower end of the pump being connected to the pipe coming from the bottom of the Boiler.
I have bled the pump and checked that the pump motor? is free to rotate. The pipes either side of the pump appear to be about the same hotness but, as mentioned previously, not as hot as they should be.

I have bled the whole system about 5 times thinking that I might have an air lock in the pipes but the 'lukewarm' heating/hot water effect is still there.

If a valve is stuck where is this likely to be as I have an open-vented CH system and admit that I am not very knowledgeable about these things!

kevplumb · 23 Oct 2004

check the airing cupboard

brumylad · 23 Oct 2004

if the new pump has 3 settings on it, like most do, try it on a different setting.

Make sure the isolation valves on either side of the pump are fully open. (turned anti-clockwise)

kevplumb · 23 Oct 2004

CLOCKWISE IS CLOSED

kevplumb · 23 Oct 2004

ok s*d it

bripl · 23 Oct 2004

from reading the post PUMP IS PUMPING UP pump is connected to bottom pipe i always thought the bottom pipe was the return?pump should be other way round if i have read it correctly.

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Lukewarm CH

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