Central Heating problems

I have a closed pressurised central heating system that seems to be dificult to bleed all of the air out of. I have had lots of work done on the house which has necessitated lots of messing with the radiattors etc. This means that the system has been drained, filled or topped up regularly. The net effect is that I never seem to be able to get all of the air out of the system, hence the pump is frequently noisy. Not only that, I think the air in the system has put a strain on the pump and I have had to replace the pump three times in 5 years! I want to avoid this happening again! Any ideas?

I don't think the system has a leak (as it seems to hold pressure OK for ages) but air still seems to get in (perhaps through the frequent topping up with 'aerated' mains water containing dissolved air). Hopefully, my period of frequent topping up has come to an end with me completing the rennovation of our old house, but can I fit some sort of automatic air bleed valve that will take out any extraneous air to make the pump (a) less noisy, and (b) last longer!?

Reply to
michael.shattock
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Pump failure rate seems excessive! I've one system which has only had 3 pumps in 25 years. Do you bleed the pumps themselves when you refill the system?

The short answer is yes. Fit it at the highest point of the pipework. The 3 combis I've had fitted all had an auto-bleed valve builtin, but in those cases the boiler was the highest point because they were in flats.

Reply to
OldBill

Is there inhibitor in it?

It's probably not air, it's hydrogen. Vent it into an upturned glass above the air vent and see if it ignites. H2 would burn with a blue flame.

Check the water with litmus paper. Anything acidic pH

Reply to
Aidan

Hi Everyone,

The problem is the rads (6) on the 2nd floor only get warm, all over, They were working ok, but for some reason they now do not get hot.

The system is new, combi boiler, three zone controls, one for each floor. The rest of the floors are ok. Am I looking at a failed zone valve, if so how can I check it?

Reply to
jaycee

Could be a balancing problem. What happens if you turn the other zones off - do the 2nd floor rads then get hot? If they do, the zone valve is ok.

I presume it's an unvented (pressurised) system? How big is the vertical separation between the boiler and these problem rads? What does the pressure gauge read when the system is cold? Are you able to bleed the 2nd floor rads ok?

Reply to
Roger Mills (aka Set Square)

Hi Roger

Yes its pressurised, vert separation approx 6 metres ( boiler in cellar) with system cold 2bar. Yes can bleed rads ok, doesn't seem to make any difference! Thanks, John.

Reply to
jaycee

MAY be an airlock.

Especially if the pipes go up to the loft and then down to the rads.

Otherwise its a balancing problem, or a sticking zone valve.

If airlock try a full speed pump and just ONE rad on - close all the others.

This should blow any air into that one, where it can be bled properly.

You SHOULD have bleed nipples fitted to the highest point of any pipework..

Reply to
The Natural Philosopher

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