Pressure drop in Worcester 240 combi boiler

Hope someone may be able help. I am losing about 1 bar of pressure overnight from my Worcester 240 combi boiler. The system has been unused for about a month whilst some other works have been going on and several of the radiators were removed for the decorator and were later reconnected.

I have initially checked for any leaks at the boiler connections and at all pipe connections to the radiators, but I can’t find any leaks at all.

Has anyone any suggestions on what the likely cause of the pressure drop could be, particularly as there is no evidence of water leakage. Is it worth putting some 'leak sealer' in anyway, just to make sure that there are no leaks where the pipework is not visible and do these leak sealers actually work? I saw some in B&Q yesterday for about a tenner and Screwfix Direct do this one

http://www.screwfix.com/app/sfd/cat/pro.jsp?cId=102633&ts=84274&id=37884

I would be very grateful for any responses as I really do need to sort this problem out. Cheers.

Mr M

Check outside. Look for a pipe coming from the Boiler to outside. Is water dripping from the pipe? If so, its the PRV letting by.

You'll need a RGI to fix it mate.

Thanks, I'll have a look at that later on. If there is water coming from the PRV what causes this and what's actually involved in the repair. I'm not going to touch it BTW but I would rather have some background info on whats involved.

The Valve seat on the PRV (Pressure Relief Valve) can be prevented from re-seating because of debris in the system.

Its difficult to estimate not knowing your area/boiler/boiler location etc etc but as a 'guess-timate', PRV will be about a Tenner. Labour to fit will be about an hour.

But remember, it may be something other than the PRV letting by. An RGI will be able to diagnose when seeing the boiler.

Mr M said:

Hope someone may be able help. I am losing about 1 bar of pressure overnight from my Worcester 240 combi boiler. The system has been unused for about a month whilst some other works have been going on and several of the radiators were removed for the decorator and were later reconnected.

I have initially checked for any leaks at the boiler connections and at all pipe connections to the radiators, but I can’t find any leaks at all.

Has anyone any suggestions on what the likely cause of the pressure drop could be, particularly as there is no evidence of water leakage. Is it worth putting some 'leak sealer' in anyway, just to make sure that there are no leaks where the pipework is not visible and do these leak sealers actually work? I saw some in B&Q yesterday for about a tenner and Screwfix Direct do this one

http://www.screwfix.com/app/sfd/cat/pro.jsp?cId=102633&ts=84274&id=37884

I would be very grateful for any responses as I really do need to sort this problem out. Cheers.

Mr M

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have you checked the packing glands are not leaking whilst the radiators are cold? the packing gland is the part underneath the plastic tops on your radiators, i usually find a little leak on one of these is enough to drop significant pressure

Blasphemous said:

Check outside. Look for a pipe coming from the Boiler to outside. Is water dripping from the pipe? If so, its the PRV letting by.

Click to expand...

I had a look tonight and yes there was a drip of water on the end of the PRV pipe. I wiped it off and waited for about a minute but no more drips appeared. I went away and came back after a couple of minutes and there was another drip of water on the end of the pipe. Did this again with the same outcome, so it looks like a new PRV may be required.

Blasphemous said:

The Valve seat on the PRV (Pressure Relief Valve) can be prevented from re-seating because of debris in the system.

Click to expand...

Just out of curiosity, would it be worthwhile turning the test knob on the PRV a couple of times to try to "blow" any debris out from the inside of the PRV, down the PRV pipe, to the outside


I reckon that the system is probably more than six years old and after checking all the pipework again more thoroughly, a couple of the lockshields each had a very small amount of water on them around the 15mm pipe connections

timmy74 said:

have you checked the packing glands are not leaking whilst the radiators are cold? the packing gland is the part underneath the plastic tops on your radiators, i usually find a little leak on one of these is enough to drop significant pressure

Click to expand...

Is my reference above to Lockshields what you are referring to timmy74 as I wasn't quite sure what you meant?

There was also a very and I mean very slight leak on the 22mm central heating flow Isolator (the 22mm compression fitting directly at the base of the boiler which is one of a number of boiler pipe connections). The Isolator I am referring to has a little turn located on the fitting that the pipe connects to and that you rotate with a screwdriver (which I assume works similar to a ball-o fix). I'm not sure whether the small turn can be removed and replaced or whether the whole compression fitting would need removing from the boiler......Perhaps somebody knows the answer to that one and what its actually called as clearly, I haven't the foggiest

Any more views on the success or otherwise of leak sealers would also be appreciated particularly the one from Screwfix, referred to in my earlier post

It may not be a case of replacing the PRV , you could have , faulty heat exchange , expansion vessel , blocked feed to expansion vessel , filling loop letting by .

as for cost , it depends on various things , make n model , location and problem


anymore RGI`s ?