Gas combi boiler increasing pressure & switching off

[mrsh77]

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 Glow-worm 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

 

[bengasman]

Expansion vessel leaking or flat.

 

[mrsh77]

Expansion vessel leaking or flat.

Thanks for the reply. Are there are easy tests I can try to see if it is definitely the Expansion Vessel please?

 

[bengasman]

Search forum and see faq; must be 1000 posts on the subject

 

[mrsh77]

Thanks for the reply. I will search for the Expansion Vessell tests we can try. In the meantime, it has been suggested elsewhere that it maybe the "overheat stat". 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?

 

[mrsh77]

I will be asking this plumber for an explanation as to why he disconnected our gas.

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?

 

[bengasman]

...In the meantime, I have called British Gas and am weighing up their 2 options:-
1) £99 repair + £20 p/month (12 month contract)
...
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?

Bearing in mind that charging an expansion vessel is a small job that most local RGI's will do for well under £100, and fitting a new EV for under £200, £339 does not sound like a bargain.

As for the "guarantees", their contracts have very interesting small print.

Just had a new client the other day who kicked BG out.
BG had "guaranteed" to repair all faults or replace the boiler if they could not.
"Yes, madam, we can repair the fault, no problem. We will order the part and be back the week after next." LIterally! Client recently had a baby and did not fance 2 weeks without heating and hot water.
And that was the 5th time they were called out since the end of this summer.

The owner called me out to quote for a new boiler, at which point I got the boiler working in less than an hour. And it still is.

The only problem turned out to be that the boiler had not been serviced properly, and the condensate outlet had failed. This particular model is known to be sensitive to lack of service. At least it is known to me and the manufacturer; BG either don't seem to know or don't care.

 

[mrsh77]

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

 

[ockyvines]

so you have paid £339 for a thermistor and overheat stat.
probably £15 for parts and 20 mins work,bargain!