Boiler loses pressure only in winter - no leaks

jpmcbrien

Hi.

I've searched the forum and found a couple of posts similar to mine already however the difference appears to be that my central heating boiler only loses pressure in winter.

My guess is, of course, that's due to my using the heating more in winter and somehow this causes the boiler to lose pressure, dropping to zero. Sometimes the pilot light will go out as well. Heating is on a timer, starting at 5pm and shutting off at 9:30pm.

Every day or two when I get home from work I'll notice a very small pool of water on the floor from what looks like a little outlet on the pipe going to the livingroom radiator. I haven't found this from any of the other radiators in the house.

Other than that there's no real indication of a leak anywhere in the house though I appreciate that doesn't necessarily mean there isn't one. All the same I'm confused as to why this happens only when the central heating's in constant use - this is my third winter here in this place and I'd like to make sense of what might be going on with the central heating!

Many thanks in advance,
Jonathan

Nick_Knock

I am surprised that no one else has replied yet.

I presume from your post that it only happens when the heating is on?

But the small puddle from the rad will almost definately be causing the pressure drop - does not take much water loss to loose the pressure on a sealed system.

Personally I would get this fixed first (ask friends for recommendation of a heating engineer) then monitor the situation.

latecomer

Is it a drain valve of some description, if so have you make sure its closed off? If you are not sure then take a picture and let us see.

economiser

It is almost certainly a leak. My system also only loses pressure in the winter only although very slightly. In my case this is almost certainly to expansion of pipework and I suspect the leak is probably where one of the TRV's is connected to the radiator. The problem with a small leak with a hot system is of course it evaporates as fast as it leaks.

bockster

if we are talking combi boiler, there will be a pressure release valve which allows water to escape outside when pressure in system is too high, ( or valve may be faulty.)
have you checked the outlet of this valve for evidence of water.
it could be that in summer, when using hot water only, in short busts, that the pressure in the system does not get high eough for the prv to 'blow'.
but in winter, with ch on for long periods, the pressure is getting higher and escaping.
this would be my guess.
see here;- http://forums.moneysavingexpert.com/showthread.html?t=1295225 post no4 for a little more info.

hope this helps.

jpmcbrien

latecomer wrote: »

Is it a drain valve of some description, if so have you make sure its closed off? If you are not sure then take a picture and let us see.

Thanks everyone for your replies, they've been helpful and reassuring.

Here's some pics of where that radiator pipe seems to leak - there's a square bit on the end that I'm sure will turn with pliers but I'm reluctant to meddle with it since, as I said above, this thing doesn't leak all the time.

agent_orange_2

If you were to open that "square thing" - turning anti clockwise, the water would drain from your heating system through the other £sticky out bit" It is a drain plug. I had a leak from the drain plug on my system even though it was tightly shut. I believe there is a little washer inside which my plumber sorted. I don't think you'll do any harm if you try and tighten the nut. Don't apply too much force though.
It's possible the system may have to be drained to replace the drain plug if it turns out to be faulty