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When we moved in to the house about a year ago, the radiators gave out great heat but now they seem just warm to touch. We have a combi boiler with fully pressurised system. The hot water is scalding hot and the pressure sits about 1.5 bar. We were advised to turn the pressure up to see if it helps heat the house better, but not making any difference. If we do this, the system seems to loose pressure - it just goes back to 1.5. All the radiators dont require bleeding. Can anyone help?

I have exactly the same problem with tepid radiators on a combi system.
Only one radiator (nearest the boiler) is anything like the heat it should be!
I just had the engineer come to attend another problem and he seems to think that the radiators need draining to remove all the silt and grunge and so
make the system flow more freely. Don't know if you consider this might help in your case? Meanwhile, if anyone knows how to drain radiators..........

[quote="casteral"]I have exactly the same problem with tepid radiators on a combi system.
Only one radiator (nearest the boiler) is anything like the heat it should be!
I just had the engineer come to attend another problem and he seems to think that the radiators need draining to remove all the silt and grunge and so
make the system flow more freely. Don't know if you consider this might help in your case? Meanwhile, if anyone knows how to drain radiators..........[/quote] hi u should hav a drain valve on a downstairs rad usually on rad nearest a exit turn off boiler let system cool down then attach a lenghth of hosepipe from the valve to a soakaway then open the valve drainoff then go round all rads on the upper levels and open bleed valves then wait till the water stops coming out the hose but be aware if u hav drop feeds on your downstairs rads they will hav to be drained seperately if problem is sludge build up remove rads once drained and flush out with a hose pipe remember to add a inhibitor wen refilling system hope this helps

Would help to add a cleanser to the system (and allow it to circulate for about a week) before you drain it.....

Paul