Boiler firing intermittently - Any Ideas?

stevegreen · 07-09-2007, 9:36 AM

Over the last few days our central heating boiler has been acting very strangely indeed. Currently we are only using to heat the water up in the tank and have it on a timer to come on first thing in the morning and again in the late afternoon however, when we came to use the hot water on Tuesday evening it was only luke warm which suggested that the timed event in the late afternoon hadn't worked.

We pressed the button to override the time but the boiler didn't fire up, the pump was working but the pilot light didn't come on. We tried the central heating and this worked (same control box, same boiler)

Next day, the time event in the morning worked and so did the evening timer.

Thursday came and the afternoon timer didn't work again and when we tried to override it the boiler wouldn't fire again, not even when activating the central heating which worked last time. Desperate for ideas, I cut the electric to the boiler, restored it and it still didn't work. Even more desperately, I waited for the washing machine to finish and tried to override it again and...........the boiler fired up

This morning, the timer event didn't work again (luckily we left it on for an hour or so last night so we had hot water) so I tested manually firing it again and hey ho it fired up first time.

I'm utterly confused as to what the problem could be, initially I thought it might be the thermostat in the boiler playing up, then I thought the pilot light was faulty, then, possibly the control box was faulty. Trouble is, at some point all of these things have worked so i'm struggling to think what it might be.

I have an engineer coming tomorrow and I guess he will be as confused as me. Has anyone had anything like this happen?

Razor · 07-09-2007, 9:41 AM

Sounds like the pcb is on its way out. I had to replace one of my pcbs this week on one of my properties and it was doing the same. The boiler was only 17 months old too.

PCB was £94 and labour was 3 hours as my Corgi guy had to go and get the part.

w3dal · 07-09-2007, 9:46 AM

I had an issue with mine a while ago where the boiler would fire up when i turned the shower on and would be hot then cold - after 4 or 5 attempts it would stay hot. I could force it to work with the central heating on.

anyway ideal came out and they replaced the burner, the board and some other bits and bobs - so in theory pretty much got a whole new boiler (flat is only 3 yrs old) and still did it.

turns out the guvnor downstairs was faulty and wasn't pushing the gas up to my boiler so it was going into safe mode (i live on the top floor).

A call to the gas board and was replaced fee of charge and it all worked fine.

might be something to suggest that they check the gas pressure cos if they had done that in the first place they would of spotted it.

Dal

stevegreen · 07-09-2007, 9:47 AM

Quote:

Originally Posted by Razor

Sounds like the pcb is on its way out. I had to replace one of my pcbs this week on one of my properties and it was doing the same. The boiler was only 17 months old too.

PCB was £94 and labour was 3 hours as my Corgi guy had to go and get the part.

Is that on the control box or the boiler?

Razor · 07-09-2007, 9:48 AM

The pcb is the brain of the boiler.

Printed Circuit Board - PCB

Its in the boiler.

961 · 07-09-2007, 9:52 AM

Could be number of things

e.g. Failed/failing hot water tank thermostat

Failed/failing zone valve

Failed/failing pump if fully pumped system

Dirty electrical contacts

Failing battery in remote programmer

Burned out pilot light thermocouple (I am assuming this is gas not oil)

However if the engineer knows what he is doing he should identify the problem in 5 mins flat

Always ensure you retain any replaced parts

stevegreen · 07-09-2007, 9:58 AM

Quote:

Originally Posted by 961

Could be number of things

e.g. Failed/failing hot water tank thermostat

Failed/failing zone valve

Failed/failing pump if fully pumped system

Dirty electrical contacts

Failing battery in remote programmer

Burned out pilot light thermocouple (I am assuming this is gas not oil)

However if the engineer knows what he is doing he should identify the problem in 5 mins flat

Always ensure you retain any replaced parts

Blimey, thats a long list!

I phoned British Gas but they wanted £156 to come out and fix it, that inccluded all parts etc from what I understood. I thought this was expensive but i'm thinking it might not be now

Razor · 07-09-2007, 10:08 AM

Quote:

Originally Posted by stevegreen

Blimey, thats a long list!

I phoned British Gas but they wanted £156 to come out and fix it, that inccluded all parts etc from what I understood. I thought this was expensive but i'm thinking it might not be now

Cheaper than what it cost me. Corgi engineers roughly charge £45-70 per hour depending on where in the country you are. Central London being the most expensive. You may also have a call out charge.

stevegreen · 07-09-2007, 10:23 AM

I must have done ok then, managed to get a Corgi registered engineer out for £10 plus £35 per hour. Mind you he will probably make about 450% on the parts

961 · 07-09-2007, 12:04 PM

Quote:

Originally Posted by stevegreen

I must have done ok then, managed to get a Corgi registered engineer out for £10 plus £35 per hour. Mind you he will probably make about 450% on the parts

See if he will do a boiler service while he is there even if he spends another hour doing it. Well worth the money

If he's any good make sure to get his number so that you can get hold of him if you have trouble in the future

If you don't fancy using him again, look up the boiler manufacturer's web site. They often have reduced prices for boiler annual service in the summer when their engineers aren't so busy. They are invariably miles cheaper than insurance based schemes or British Gas etc. Boilers that are serviced annually tend to keep going when you've got frost on the car windscreen and a turkey in the oven

Rich · 07-09-2007, 3:42 PM

We had a similar problem with our boiler, we called somebody out who said the pilot light/igniter was dusty. He just hoovered it out and it worked straight away.
It's happened again recently, so I hoovered it out myself and it worked a treat.

dazzafact · 07-09-2007, 5:13 PM

Quote:

Originally Posted by stevegreen

I must have done ok then, managed to get a Corgi registered engineer out for £10 plus £35 per hour. Mind you he will probably make about 450% on the parts

Or tell you because the pump and the pcb have gone then you may as well get a new boiler installed for a couple of hundred quid more.

I have had a couple of corgis out to look at my old combi that knacked within 2 years( cause the corgi guys that fitted it were sh!t) and they said that my pcb was knacked and my pump was about to go. Neither was true, nor did any simple fault finding indicate so. A corgi registered bloke does not mean he has any idea about boilers, much to my dissapointment.