problem with boiler

[nextqueen]

got a combinaton c28 boiler. just before xmas and last night, both times it has stopped working. the pressure has dropped and so a valve has had to be opened to create one bar of pressure. the switch on the wall was turned off for a while then turned back on. the hot water was run in the sink which then made a flame visible and effectively showed that the boiler was working again. why is this happening? we have got cover out on it but now its back to 'normal', should i call them out? should i tell them what has been done to rectify it or just let them look inside and find the problem themselves? its a real pain as you can imagine.

[albaqwerty]

I'd get them out for a look. There might be a leak inside the thing.

Hate new boilers, Our CH system was replaced at end of October last year and we've had the "gas-guys" out 7 times now.

The boiler man 'fixed the boiler a week ago today and the pressure dropped on it AGAIN yesterday.

[boxtops]

We must be lucky then, we've had a combi boiler for 5 years now and the only time anyone's had to come out is for the annual maintenance (he's coming again today). I hope this post doesn't tempt providence.... ;-)

[nextqueen]

so do i say ive messed with it or what? what makes it happen? might just be told its our water pressure, hope not!

[albaqwerty]

sshh boxy, fate has now been tempted :)

[boxtops]

I would keep schtum, nextqueen - if you are on a maintenance contract then there might be something in the terms which says "customer doesn't mess with it, or the contract's not valid". They might be able to tell though....

[nextqueen]

thats what i was thinking boxtops, will be hard to say nothing though without me mentioning water pressure, they might not find anything wrong. im really wondering what causes it though!

[albaqwerty]

I'd come clean. No pressure = no heating or hot water.

After the first visit we had, I asked them to show me how to top the boiler up. Nice man showed me how to do that.

[boxtops]

Just ask an innocent question then "can it be the water pressure"?

[nextqueen]

but for us to have got it working again, surely they will know that we have touched something?? im still in two minds whether to get someone out now its back working.

[albaqwerty]

Wait until the pressure drops again (which I hope it won't) then get them out in all innocence.

To find out why it happens, I reckon you'd have to ask them as I've no idea, sorry.

[nextqueen]

yes, think i will leave it then and wait until next time, hopefully not, at least we know how to get it back working i suppose. the first time however was dreadful when we had extreme temps and no one could come out for days and they rang me 12 days later.

[boxtops]

My boiler-man's here now, ssshhh.....

[landscaper2]

We had some building work carried out last year, which included extending the heating system and fitting a new combi boiler. For about 3 months the pressure needed topping up every couple of weeks. The fitter said to vent the rads, keep topping it up and it should settle down - which it did and I havent touched it since Christmas.

[The Builder]

Usually, if the pressure keeps dropping, it's a fault in the internal pressure vessel. The fact that it "fixes itself" suggests, maybe, the safety valve that regulates this pressure is opening up intermittently.
Either way, it needs to be fixed.

I'm quite suspicious of some of these "cover" situations. I can't help thinking that someone, somewhere is saying "don't spend too much money on this....... unless you really have to"
Doc Spock would know more about this than I do.

[pilotlight]

nextqueen, If it has taken 3 months for the pressure to drop back down to the point where the boiler shuts itself off, I would personally be thinking that the cause could be a very, very small water leak somewhere on the heating system.
This could possibly be on one of the compression joints on the radiator valves. It does not need to be dripping out, just a sign of dampness would cause your problem over a prolonged period.
Check all of the valves by holding a piece of tissue paper around the joints, if the paper shows any sign of wetness, this could be the problem.

On the other hand, Builer could be correct. But I would try this.

Hope this helps.

[heathfield]

If it's a very, very slow leak, you might have to do Pilotlight's tissue paper test with the system cold. I spent ages looking for a similar leak. The reason I couldn't find it was that the water was drying up quickly enough at the hot leaking joint to leave the joint dry. Only when the system was cold was the joint wet.

[Hymie]

For whatever reason, you are loosing pressure (due to a leak) from within the central heating system of the boiler. The leak could be within the boiler itself or it could be a faulty pressure relief valve, leaking the water – or a leak somewhere along the radiators and pipery within the house.

To eliminate the pressure relief valve, secure a clear plastic bag over the pressure relief outlet using a rubber band (the pipe outlet opening should be positioned outside the property, close to the boiler). Should the bag collect water, the problem is with the pressure relief valve, allowing the leak.

Check everywhere within the house, beneath radiators and pipes for damp patches – bear in mind that the loss of as little as 500ml of water from the central heating system could reduce the pressure sufficiently to cause the boiler to switch off.

If the leak is within the boiler, and its operation is drying out the leak – this will be more difficult to prove. But once we encounter warmer weather and the boiler is on less frequently, the leak from within the boiler may show itself by water dripping from the boiler.

In the meantime to keep the boiler operational – keep pressurising the central heating system, but remember that the water is going somewhere.

[AlBags]

Those relief valves never leak tho ..

Check all the radiator lockshield valves and connections for slight leaks.
System pressure top-ups normal for any system once in a while .. and especially after work done to system.
If system has been significantly over-charged for long .. pressure vessel may have been damaged.

[AlBags]

PS.
Relief valve : approx 3 bar (40-45 psi)
System charge pressure (cold) no more than 1 bar on gauge.