Boiler only fires up when plenum chamber cover is removed

[Sarie]

Hi all, I'm new here but trying to solve an issue with our Ravenheat boiler. It's an RSF 820/20 boiler.

The pilot light is on but we've had an issue where the boiler takes a while to fire up when you put the heating on or run the hot tap. This has gradually become worse recently and sometimes it can take up to 5 minutes for the burners to fire up.
Originally we contacted Ravenheat and were told it was symptomatic of the air pressure switch malfunctioning.
We removed the switch and gave it a good clean and re-fit it. Upon doing this we thought we'd seen an improvement but actually realised it was because we'd removed the plenum cover during the process of locating the switch. With the plenum chamber cover back on we see no improvement.

We ordered a new air pressure switch just to be sure it wasn't that as Ravenheat tech support still suggested that it was most likely the cause of our fault and suggested we swap it out as it's a common fault.
We fitted the new switch but if anything the issue is now worse with the boiler failing to fire up entirely. We now cannot get it to fire up even after a significant period of time but the pilot light is still lit.

If the plenum chamber cover is removed the boiler will fire up immediately 100% of the time but as soon as it is screwed back on the problem starts again.

We obviously don't want to tinker with anything that could be a danger but if we could get a clearer idea of what the fault could be we can hopefully find a simple solution, if not we'll be forced to call out an engineer probably at great cost

Any advice much appreciated, thanks !

 

[Bunnyman]

You have removed your boiler combustion chamber cover You must get an engineer to look at this it's registered engineer you need ,! It's not a DIY fix

 

[Sarie]

You have removed your boiler combustion chamber cover You must get an engineer to look at this it's registered engineer you need ,! It's not a DIY fix

We were trying to get to the pressure switch... didn't realise it was on top of the boiler and we didn't need to remove the cover. We were just following the manual.

In removing the cover, have we affected the pressure in the chamber then? It didn't seem like a big deal removing the cover in question.
The cover we removed is just a big piece of metal with about 9 screws holding it on. Behind that there's a smaller chamber with a glass front containing the gas burners which obviously we haven't touched...

 

[muggles]

Removing the cover will have indeed affected the pressure in the chamber, and the way your boiler burns. Did you check the condition of the seals on it before you replaced it?


A few notes, given what you've said so far:-

An Air Pressure Switch is a safety device connected to the gas valve, and should not be played with by DIYers who don't know what they're doing. I'm disappointed that Ravenheap were prepared to give you advice on this, but that's another story...

The APS is not your problem, I knew that from the title of your article, unfortunately you've gone to the expense of buying one to find this out. I can't tell you what the problem is though as it's related to the gas train, and as such giving advice is against forum rules.

A good service should cure it, if the person you employ knows what he's doing. The most likely cause is something that should be checked on a service anyway, so an engineer interested in keeping your business may well include it, unless of course you've managed to break something else with your tinkering. Whilst I can't comment on engineers in your area, to give you a guide we charge £60+vat for a standard boiler service.

 

[flameport]

We obviously don't want to tinker with anything that could be a danger

What could be more dangerous than removing the combustion chamber cover and firing the boiler?

 

[Sarie]

Removing the cover will have indeed affected the pressure in the chamber, and the way your boiler burns. Did you check the condition of the seals on it before you replaced it?


A few notes, given what you've said so far:-

An Air Pressure Switch is a safety device connected to the gas valve, and should not be played with by DIYers who don't know what they're doing. I'm disappointed that Ravenheap were prepared to give you advice on this, but that's another story...

The APS is not your problem, I knew that from the title of your article, unfortunately you've gone to the expense of buying one to find this out. I can't tell you what the problem is though as it's related to the gas train, and as such giving advice is against forum rules.

A good service should cure it, if the person you employ knows what he's doing. The most likely cause is something that should be checked on a service anyway, so an engineer interested in keeping your business may well include it, unless of course you've managed to break something else with your tinkering. Whilst I can't comment on engineers in your area, to give you a guide we charge £60+vat for a standard boiler service.

No we didn't check the seals.
I've only lived there a few months myself and was a bit shocked to be told the boiler hasn't been serviced for about 6 years so I'm not entirely surprised it's playing up. I'd suggested we get it serviced but as it's been playing up so much the service was put aside whilst we tried to get our hot water back up and running. Looks like we should've just had it serviced. Fail.

As for the APS, I'm a little annoyed at Ravenheat if that's the case.. we asked them about the fault directly and described it long before we attempted to fiddle with anything and they were the ones who suggested we replace the APS as it's a common fault and according to them causes all the symptoms we've been having.
Thankfully the part didn't cost us too much but it's still a waste :/

Thank you for your advice, I'm sure we sound stupid but we just assumed if it was something we couldn't fix ourselves we wouldn't be advised on it by Ravenheat so from their emails we presumed it was a simple thing we could change ourselves without needing any major works. We had intended to swap the switch to get it all working again and then take out boiler cover and get a service done under the cover once all was up and running again.

Anyway, we'll get an engineer booked for a service. I doubt we've broken anything else as we haven't tinkered with much, all we've done is swap the APS over and take the plenum cover off and put it back on again.

 

[gaswizzard]

Brace yourself for more than just a service.

 

[Sarie]

Brace yourself for more than just a service.

Any idea if British Gas servicing is any good? Their website claims they'll come out and do an inspection for free then quote for their service based on what they find. It also says that quote includes all parts and labour, a safety check and a 12 month guarantee on workmanship and parts.

Sounds good... unless they turn up, have a nosy and then turn around and say it'll be £300

 

[muggles]

British Gas will most likely turn up, suck air through their teeth and tell you your boiler needs replacing. Much better to find a reputable independent boiler engineer. It's far from the best boiler in the world and I'd start saving for a new one now, but it should keep going for a few years yet. Certainly doesn't sound like there's currently anything majorly wrong with it

 

[Sarie]

British Gas will most likely turn up, suck air through their teeth and tell you your boiler needs replacing. Much better to find a reputable independent boiler engineer. It's far from the best boiler in the world and I'd start saving for a new one now, but it should keep going for a few years yet. Certainly doesn't sound like there's currently anything majorly wrong with it

Yeah we'd already heard one of our friends was told by British Gas to replace his boiler when there was nothing wrong with it so we half expected that already...
Finding a reputable independent boiler engineer is the issue though. I'll ask around and see if we can come up with anyone.

I suppose we should start saving up to be on the safe side; We were just hoping it'd survive a while longer as we're looking to sell the house in the next 18 months or so and if we could avoid a costly boiler replacement in that time that'd be nice.

Thanks again for your help and advice, we'll get on the phone tomorrow to see if we can find a good engineer in our area

 

[biscuit77]

Get british gas out mate, one off fixed price repair and they probably will ADVISE you to change the boiler, but they'll still fix the boiler. Its up to you if you want to change your boiler, only ADVICE.

 

[Sarie]

Just to conclude this thread...

We called British Gas out in the end as they offered to do a fixed price repair and service for £99 if we signed up for their boiler cover for 12 months which we wanted to do anyway.

They came out and as it turns out it was indeed the Air Pressure Switch; there was a slight kink in one of the pipes we'd overlooked. The fan was also a little clogged with muck. Once cleaned out the whole thing worked just fine.

The first thing the engineer did when he arrived was to remove the plenum cover and fire up the boiler and then say "Ah must be a fault with your air pressure switch".

So we DIYers who don't know what we doing apparently do know what we're doing and had we actually spotted the kink we'd probably have had a working boiler again...

Anyway, he did a full service and we're now covered for anymore mishaps so thanks for the advice folks. Clearly we're not as daft as some of you made out

 

[nickso]

So we DIYers who don't know what we doing apparently do know what we're doing and had we actually spotted the kink we'd probably have had a working boiler again...

Probably not, the fault is far more likely to be the clogged fan/venturi which I doubt you could have made the leap to.

I'm sure many of us were thinking that but certainly were not going to tell you about it incase you cocked it up.

 

[Sarie]

So we DIYers who don't know what we doing apparently do know what we're doing and had we actually spotted the kink we'd probably have had a working boiler again...

Probably not, the fault is far more likely to be the clogged fan/venturi which I doubt you could have made the leap to.

I'm sure many of us were thinking that but certainly were not going to tell you about it incase you cocked it up.

OH had already taken the view that the fan/venturi was the next bit to look at if the APS didn't fix it but we had decided enough was enough and we wanted it fixing safely by an engineer (he'd made the leap to that because if you tapped the fan the boiler would often kick in and it's also related to air flow).
But our assumption that it was air related was correct whereas we'd been getting messages from engineers suggesting that some part of the gas train was likely to be at fault and implying we were ignorant for suspecting air flow. Heh.
Love how we got so much abuse on some other forums when enquiring about this when it turns out we were pretty much right

I'm just glad we finally have hot water again and now have boiler cover so we don't have to worry about anymore issues in future and can just call out an engineer free of charge.

 

[45yearsagasman]

Much better to find a reputable independent boiler engineer.

That might not be an easy task