Leaking Radiators

[doriclad]

I have recently moved in to a house with a new Combi boiler / central heating system fitted. I don\\\'t have much experience of combi boilers - my last property was all electric.

1. When I moved in boiler / radiators were working fine - no leaks etc. - but I did notice the radiators were making a noise and decided to vent them which released some air in the system.

2. Next morning there was no CH or HW and the boiler would not start. The pressure had dropped to 0 bar. My neighbour (plumber) refilled with the flow / loop pipe and brought the pressure back up to about 3 bar. Two of the radiators began to leak at the valves so he tightened them up. I put kitchen roll down to monitor further leaks.

3. When I arrived home in the evening the radiators had leaked more. I also noticed a puddle under the boiler and that the pressure had dropped to about 1 - 1.5 bar. As the pressure had dropped I decided to bring it back up to 3 bar again by refilling with the flow / loop pipe. I then went back and tightened up the radiator valves further.

4. This morning I noticed that two of the radiators still have a leak. However the boiler pressure seems to be just above 3 bar.

What pressure should the boiler be at?

If you bring it up to say 3 bar, should it reduce and level off at say 1.5 bar?

Would there be anything wrong with the valves / joints in my radiators or is it just that the pressure is set too high (i.e. will they leak slightly until the boiler reaches a comfortable pressure?

Thanks in advance.

 

[IanDB]

The recommended pressure is between 1 and 1.5 bar. At 3 bar the pressure relief valve lifts and lets water (and hence pressure) out of the system. (The puddle underneath your boiler!) Are you sure your plumber knows what he's doing?

The pressure should stay fairly constant - rising slightly when the heating is on. If the pressure goes back up to 3 bar then you might have a problem with the expansion vessel.

There is normally a low pressure cut off switch in the boiler which is why the system wouldn't fire up at 0 bar. If you ever bleed the system you must re-pressurise via the fillling loop.

Hope this helps.

 

[doriclad]

Thanks for your help. You mention the puddle under the boiler due to high pressure - would this also be a reason for the radiator leaking at the valve?

What is the best way to release pressure back down to 1 - 1.5 bar? Or will the boiler gradually do this and should the leaks stop once pressure drops?

 

[IanDB]

Could be. If the system was running OK before anyone touched it and it's only leaked since the pressure went up then that's what the problem was. 3 bar is approx 45 psi so if there's any chance of a leak then it will certainly happen then.

The puddle of water under the boiler will be from the pressure relief valve (looks similar to this http://www.plumbworld.co.uk/0000-55 if you want to have a look round your boiler).

Unfortunately once these valves operate they have a tendency to weep although they can stop after a while. Just keep an eye on it.

You have two ways of reducing the pressure, firstly by twisting the cap on the PRV to operate it manually - but I wouldn't recommend this for the reasons above, the other is to bleed some water out of a radiator. It has the same effect.

As regards leaks, I think you'll find that once they've appeared they'll continue even after the pressure's dropped. Your system should be watertight to 3 bar anyway. If tightening up the leaking joints (gently) does the trick then you should be OK.