Gas combi boiler increasing pressure & switching off

henderson1977

Hi all - the original problem was a combination of the water pressure decreasing sometimes and increasing other times, both resulting in the boiler making a 'click' sound & the pilot light going out within an hour or so.

We have bled all radiators and cannot see any visible signs of leaking at the boiler or any of the radiators. We suspect the increasing pressure problem may be caused by a blockage in the system somewhere in the boiler or a radiator(s).

A plumber cleaned out the system & fitted an inhibitor to prevent the system from clogging up in future, however...

Now the boiler runs normally at about 1 bar of pressure, with the pilot light lit & hot water flowing fine. When the central heating is switched on, the pilot light flame increases as usual & the radiators begin to warm-up. The water pressure increases gradually to 2 bar after 10-15 mins, the boiler makes a 'click' sound & the pilot light goes out which has the knock-on effect of no hot water (obviously). So we have to re-ignite the pilot light to get the hot water working again, but the cycle begins again if we switch on the central heating. Also, even when the pilot light is lit as normal, there sometimes is no hot water. On closer inspection, we notice that although the pilot light is on, it's not fully lit to heat the water running out of the tap.

Before we consider getting another plumber out, can anyone offer any advice on this please?

It's a Glow Worm Compact 80p Fanned Flue Combi boiler with Honeywell gas control (about 10 years old).

Thanks
Scott

gas4you

Sounds like the boiler is going to overheat. I believe the pilot is in series with the overheat stat, via the interrupter, on these boilers.

Could be a faulty o/heat stat, but more likely a lack of circulation/flow.

henderson1977

Thanks for the reply. Is there an easy test we can try to confirm whether it is a faulty "overheat stat" or not please? It has been suggested elsewhere that it maybe the Expansion Vessell. How much would it cost a plumber to replace either of these parts please?

Another plumber visited today and said our boiler was dangerous because it could be leaking carbon-monocide, condemned the boiler & disconnected the gas supply to the boiler. He said if we didn't let him do this, he would report us to the authorities (gas board?) & they would disconnect our gas supply from outside. He said we need a new boiler, quickly produced a quote of £1750 & is pressuring us into committing to a Saturday installation by lunchtime today (Tues).

Is this acceptable or are we being paranoid to think he's a pushy saleman?

gas4you

Sounds a bit pushy to me from here.

How did he determine co was being produced from the boiler to the room?

Assuming your boiler is dangerous, then you need to get 3 quotes and not be pushed into a quick decision.

The only thing waiting will do is keep you cold for longer.

macman

Are these 'plumbers' you keep calling in actually qualified to work on gas appliances, e.g. are they GSR? You need to call an RGI, not a plumber. Some plumbers are GSR, many are not.
I wouldn't touch Mr Pushy with a bargepole, I note he said it might be leaking CO? Well, if he tested it properly, he should be able to say with certainty if it is or it isn't.

henderson1977

Agreed. I will be asking this plumber for an explanation.

In the meantime, I have called British Gas and am weighing up their 2 options:-
1) £99 repair + £20 p/month (12 month contract)
2) £69 0-30mins repair / £189 30-120mins repair / £349 120+mins repair (one-off repair fee tarrifs)

I think it's better value to go for option 1 because it's the same price (£349) as the one-off fee if the repair takes over 2hrs but the monthly policy also covers the 'full central heating system', not just the boiler for 12 months. Oh, and if they cannot repair then it won't cost a penny because of their "no fix, no fee" policy.

Sounds like a good deal?

Gasmanterry

It sounds as if the pressure vessel (Large Red Cylinder in the boiler) of your boiler has failed. If your Hot water works fine and the pressure only climbs when the heating is turned on im very sure it will be this.

Service contracts are a waste of money the ammount of jobs i go out to because british gas or other companys wont be there untill a week later is unbelivable.

Just find a local recomended GAS SAFE REGISTERED plumber to do the work, it will cost you less and you should have someone you can rely on to come at anytime if your boiler breaks again!

macman

henderson1977 wrote: »

Agreed. I will be asking this plumber for an explanation.

In the meantime, I have called British Gas and am weighing up their 2 options:-
1) £99 repair + £20 p/month (12 month contract)
2) £69 0-30mins repair / £189 30-120mins repair / £349 120+mins repair (one-off repair fee tarrifs)

I think it's better value to go for option 1 because it's the same price (£349) as the one-off fee if the repair takes over 2hrs but the monthly policy also covers the 'full central heating system', not just the boiler for 12 months. Oh, and if they cannot repair then it won't cost a penny because of their "no fix, no fee" policy.

Sounds like a good deal?

No, it sounds absolutely terrible! You don't need BG or a service contract (which will exclude pre-existing faults anyway and has numerous exclusions). You need to get a local recommended GSR RGI (not a 'plumber') who is familiar with your make of boiler. They will fix it a lot cheaper than £329-that is about half the price of a new boiler!
That time-scale charge is a blatant con-if they go one minute over 30 mins (which of course they will) you pay the next (huge) increment up.

henderson1977

British Gas replaced the "overheat stat" and "thermistor" last Thursday and our boiler has been working flawlessly for over a week now. All included in the £99 fee. Yes, we also pay £20 p/month to get this deal, but we think it's worth it for the peace of mind. We think this price plan works both for us, the customer, and British Gas so it's in their interest to fix the boiler as quick as possible, which is exactly what they did. BIG thanks and thumbs up to British Gas!!

I hope this personal account helps others in a similar situation avoid plumbers who aren't skilled enough to diagnose the problem and other plumbers who inaccurately "condemn" a boiler just to rip off folk, a.k.a. cowboys!

Thanks to all who replied and helped us on our quest to repair our, otherwise, perfectly functioning boiler.
Scott