Central heating just doesn't work properly anymore.

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19 Dec 2008
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Surrey
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Hi. Have a fairly large house, 13 rads. Gasoil boiler. Heating used to be ok many years ago, but boiler broke down a while back, couldn't afford to get it fixed so had no heating for about three months during a really really cold snap. Couldn't have happened at a worse time really, because it seems having a freezing cold damp house for three months caused an awful lot of problems we've now got (constant damp, mold problems etc.).

While I'm getting on top of those issues the central heating has never been right since I got the boiler fixed.

First of all, when it's on, only some of the radiators seem to get hot. Others either only get slightly warm or they get hotish around the top but never warm up throughout (always cold at the bottom).

I've tried balancing the system following various guides. It made absolutely no difference at all. i wasn't even able to complete the balancing because I just wasn't seeing any clear differences in temperatures with any of the rads no matter what i did. And some of the rads don't even have lockshield valves on them (they're ancient rads though, probably put in when the CH was first done in the 70s).

The boiler is working fine now, is set up properly so it isn't that. I'm suspicious the pump isn't working anywhere as well as it should be (it's rather old now, I think it was put in about 15 years ago). it's on the max power settings. it is working I think, since when it's on you can hear it running if you put your ear to it, and in one room in particular where there are a few pipes it makes a clear resonating sound through the pipes.

What I'm not sure is if it's working enough to circulate the water properly.
Also air gets into the system somewhere but I cannot find any evidence of leaking. The first rad to get hot in the system always seems to be the one that fills up with air, none of the others have this problem. I was always having to bleed it until I got fed up and put an auto bleeder valve on it.

That rad incidentally always gets red hot throughout. I was going to empty the system, and fill it again, so I bought some rad cleaner off the shelf from B&Q. I don't think I had enough to be honest since when i bgot it home I realise the system was probably bigger than the one tub was meant for, but I couldn't think of anyway to put it into the system except into the expansion tank in the loft. So I did. It doesn't appear to have made any difference what so ever. I still need to empty the system but I'm thinking if I do that and the water runs clear and I still haven't solved the problem, wha next is there to do?
 
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The last one I called to fix a leak charged me 200 quid inc vat. I really can't afford that sort of thing at this current time.
 
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Sounds like a major issue with a build up of magnatite. Air being drawn in is probably due to a blocked cold feed you can check this by holding a magnet on the cold feed pipe where it tee's into the flow pipe from the boiler. The rest is probably hydrogen that you are venting which is a bi-product of magnatite. It might be an idea to add some sentinal x400 and run it for a week or so(follow the manufacturers instructions) and take the radiators off and take them outside and flush them with a garden hose. Don't go to B&Q go to screwfix. It might all be a bit to much for someone who isn't sure so you may need to get someone in.
 
What kind of system do you have? Y-plan, S-plan? open vented or sealed system?

You may have a blockage around the feed/vent which will give you this problem, plus it will be pumping-over and pulling in aerated water which is why your rad needs bleeding all the time.

If all this is jargon to you then you will have to bite the bullet and call a plumber.
 
It's a y-plan, open vented. A blockage somewhere would certainly explain some things. I have a fairly powerful magnet actually, might try running it along some feed pipes to see what happens.

The gas coming out of the radiator certainly smells funny. Suppose the first thing that comes to mind is a week-old fart.
 
First of all, when it's on, only some of the radiators seem to get hot. Others either only get slightly warm or they get hotish around the top but never warm up throughout (always cold at the bottom).

And some of the rads don't even have lockshield valves on them (they're ancient rads though, probably put in when the CH was first done in the 70s).

the problem, wha next is there to do?
Rads are probably sludged :idea: No lockshield - no valve at all - only one end - a one pipe system :idea:
 

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