MegaSack DRAW - This year's winner is user - rgwb
We will be in touch
Hoping there may be a heating eng out there or someone with some knowledge who can help me.
My boiler has gradually been loosing more and more pressure - I've been topping it up but noted that it lost .5 bar in 36 hours this week.
I've looked at all the pipes where possible and can't see any leaks or wet patches (as this has been going on for about 12-18 months would expect something visible). I've even been under the house to check and nothing visible.
My thoughts are that something is going on with the boiler but not sure what.
Otherwise I might get some central heating leak sealant and inject that into the system.
Its doing my head in. Worried that when I go away later in Jan for a week that my boiler will shut down and I've get some frozen / burst pipes.
Knackered diaphragm in your expansion vessel, or something along those lines my plumber mate told me - mine does the same.
Where would the water go to if that was the case?
A quick Google search came up with this......
It may also be a faulty expansion vessel.Combi boilers operate on a "sealed system". This means that as the water heats in the heating circuit it has nowhere to expand into. For this reason an expansion vessel is incorprated into the boiler and is a vessel which is divided by an elastic membrane.
The membrane is strong enough to maintain the pressure in the system, but "gives" as the water heats and expands.
If it is beginning to fail it is no longer strong enough to maintain the pressure in the system and gives the impression that water is leaking away.Unless you have disturbed your piping or radiators for any reason, a failed expansion vessel is a more likely explanation for your problem.
They can be replaced but it is a job for a plumber.
[url= http://uk.answers.yahoo.com/question/index?qid=20100223155039AAx67uo ]Another answer here[/url]
Things I have had which caused this:
1) leak from a rad or a joint under the floorboards.
2) pressure relief valve have a look at the pressure relief outflow and see if its wet.
On worcester boilers 2) is a piece of micturate to fix, 1) is a case of tracing the leak, it only takes a weep to gradually lose pressure.
I've got four worcester boilers (10years old, 7, 7 and 9 years old) and look after a house with a baxi and another with a Violent, and none of them have ever had a pressure vessel go, normally down to leaks. annoyingly my brother a plumber says the pressure vessel is very common..
There a couple of real plumbers on here who could answer this properly, but chances are they are out fixing bust boilers, very busy this time of year..
Got a bottle attached to the boiler overflow and no water, hence why I was asking where the water would go.
Can't find any leaks in the system on any of the rads. The loss of pressure has sped up recently so I'm surprised I've not found the leak.
Should have mentioned its a 10 year old Ferroli (fairly basic).
All these probs started when I had it serviced for the first time in 5 years about 18 months ago.
Leaks under boards or on ground floor?
Otherwise it sounds like they might be right, I assume when the digafrigm goes the water leaks in to the others side of the diga frigm?
Nah - was under the house this afternoon checking all the pipes and nothing. Checked all visible pipes and rads but no leak. Only ones I've not done are those under the bedroom floor but I imagine I'd see a stain in the ceiling.
Whats a diga frigm? Just worked out I think you mean diafram
If you recharge the system and then leave the boiler off does the pressure still drop ?
What kind of boiler do you have? ie combi or conventional with a hot water cylinder
Combi boiler.
I think the pressure does drop when its off, but haven't conciously tested it as its really cold and the wife and kids would moan if we had no heating.
you have a leak !!!!! look under the floorboards if you can... we had similar problem few months ago... i checked all radiator pies for leaks-couldnt see any...eventually the problem was under the bathroom floor boards.. leaking pipes.
First check would have to be the PRV, I realise you have a bottle under it but the amount of water you are losing is very small.
Second would be to recharge the system and then isolate the boiler from the system to see whether the pressure is being lost from the boiler or the system.
Ahh dropoff is wise.
Can you believe it... !
Been trying to work out what is going on for weeks and just as I decide to get some help in and post up on STW the fog clears and I find out what is what.
Was downstairs getting the kids ready for bed and while doing so looked at the ceiling in a place I'd not really considered before and noticed a little puffed up plaster. Got a chair and poked it with my finger and water dribbled out! I think I may have found my problem. 🙂
Annoyingly its in the kids room where I need to get the floorboards up so will have to wait till the morning now. But well pleased I've found the problem.
Thanks for your help! 🙂
Told ya, always a leak...
see i was right as i stated above and im a woman ! 😉 
yeah but elaine anne you just copied me, I said it first, yes I did.
I wouldn't had believed either of you if I'd not found the leak. 😉
Joint first I'd say
I'll let elaine anne have it, I'm right so often it's less important to me now..
The law of averages mean that even women and children will be right some time, given that they invariably choose the most obvious answer.
So that is based on luck rather than knowledge 😉