Heating issues. Had new water pump fitted 3 weeks ago, new 3 port valve 18 months ago, boiler is 4 years old. I balanced radiators when new pump was installed and for 2 weeks or so the heating and hot water worked a treat. 3 days ago, woke up to find neither working properly. Timer comes on, boiler fires up but radiators downstairs not getting warm. Hot water not great. Balanced radiators again and all was fine but last two days every time I turn heating on nothing warm downstairs in spite of balanced radiators two days ago working fine. Pump does seem to work fine when it runs quietly but each time it starts there is a whirring noise and you know it won't work properly. Any ideas?
Discuss Any ideas? Unreliable heating. in the Central Heating Forum area at PlumbersForums.net
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What’s the make of the pump ?
Grundfos
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Black one or red one ?
Black
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Ups3 any red lights when running / having problems?
Radiators are bled, upstairs all hot but nothing downstairs. Inlet valves are warm but nothing getting into rads. All balanced 2 days ago and working fine.
How many rad? and is it a sealed or open vent system with a Feed&Expansion (small) Tank in the attic.
If a sealed system ensure that the system pressure is 1.5bar cold.
If a OV system, present setting of CC3 at 6.4M is too high IMO and can cause air ingress.
Suggest, in either case, c/o to constant pressure setting 2, CP2 which is 4.5M.
Press the setting button for ~ 3 secs until the yellow LED illuminates at the far right, then briefly press the button until the green LED and the yelloe LED next to it are also illuminated, you are now on CP2 at a constant 4.5M head.
(Also, these pumps have had more than their "fair" share of failures.)
If a sealed system ensure that the system pressure is 1.5bar cold.
If a OV system, present setting of CC3 at 6.4M is too high IMO and can cause air ingress.
Suggest, in either case, c/o to constant pressure setting 2, CP2 which is 4.5M.
Press the setting button for ~ 3 secs until the yellow LED illuminates at the far right, then briefly press the button until the green LED and the yelloe LED next to it are also illuminated, you are now on CP2 at a constant 4.5M head.
(Also, these pumps have had more than their "fair" share of failures.)
I think it is an open vent system. I have no way of setting system pressure and I know there is a small tank in the attic. We have 5 rads upstairs and 7 downstairs. I will follow your instructions and see how we get on. Cheers.
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Pumps set too high and probably drawing air in, causing your downstairs circuit to air lock. The new Grunfos ones are more powerful than the old, you'll probably easily get away with I or II on the new model.
Thank you. Lights now flashing like in screenshot on Constant pressure 2. Should I restart system to deal with airlock downstairs?
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Bleed any rads. Turn HW on, on it's own. Let it circulate round the HW system. When Hot and returning, turn HW off and CH on. Let upstairs rads get hot, when they're hot turn them all off and it should force it through to downstairs.
See how you go on 2, if it keeps airlocking you may need to turn it down to 1.
When you have done the above go up to the attic and get someone to stop the boiler and watch and see if any spurt of water from the vent when the pump stops probably a few minutes after switching off the boiler, then get them to restart the boiler/pump and watch again for any pump over.
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