Strange Boiler Operation

[Wardie72]

Hi all, just hoping someone could point me in the right direction as my boiler is doing (what I think) some strange things.

Potterton Suprima 50L - looks like it had a new board fitted a few years ago (5102160) so I'm hoping it's not that.

It constantly cycles:
Orange/Green light flashes for a few seconds
Fan turns on
Ignitor starts
Lights ok
Green Light goes constant
Cover starts to bang and what sounds like air blowing out in pulses(?) (5-10 seconds)
Shuts off and light goes Orange
Light goes back to Orange/Green flashing
Repeat

It can get very windy here and I've noticed on a particulalry bad day the boiler won't run for longer than about 15-20 secs before cycling. However on a calm day it'll run ok (plenty of hot water, heating etc.) BUT only if I unscrew the front cover a few mm to 'relieve the pressure' (the banging is greatly reduced) - I know this is not advisable but I'm just trying out different things. Obviously when the wind gets up again, the smell gets pretty bad so I tighten it up but then it shuts off.

I tested the pressure switch and it seemed ok. I then had a British Gas inspection done (the one where they come and look over the system before you take one of those contracts out) he said before they could proceed the pressure switch is faulty and needs replacing - other than that everything else seemed ok. He quoted £120 for the switch & fitting. I asked what else it could be if it wasn't the switch and was told it couldn't really be anything else.

I bought a replacement Honeywell from boilersparesuk, fitted it and still get exactly the same problem! Is it likely that the switch is faulty or could it be something else? For example the flue outlet is on the front of the house about 5-6m horizontally from the boiler (like I say it can get windy here), just opening the cupboard door which houses the boiler you can hear the wind blowing down the hole for the flue...could this be some of the cause?

Thanks guys, sorry for the long post, I thought the more info I supply the better!

 

[Agile]

We cannot give you advice on gas matters on an open forum. You have already been doing potentialy dangerous things.

As you are not qualified you should not have changed the air switch.

It seems you took advantage of British Gas to give you ( free ) information to help you try to fix your boiler.

Do the proper ting and call a boiler engineer!

Tony

 

[twgas]

the flue outlet is on the front of the house about 5-6m horizontally from the boiler

it's too long.

 

[Andygasman2010]

As Tony said it sounds like you've been doing some potentially dangerous things so far so I wouldn't go any further. You have a flue issue, it might be damaged internally or as twgas said, it's too long.

The flue needs inspecting by an RGI

 

[45yearsagasman]

If its a standard flue then at 5-6 metres its too long.Max length is approx 3.5-4.0 metres.Get an RGI to check.Its all in the MI's

 

[Blackadder43]

Unscrewing the covers?
Flue lengths of up to 6metres...
My god....
I hope you dont have a wife and children?
If you do pack them off to her mothers for a while...
Do the right thing and call an engineer in......please

 

[Wardie72]

Thanks for the replies, and the warnings.

I do appreciate the risks associated with loosening the cover, please be assured that this was not a long-term or even a short-term solution but something I did for the sole purpose of trying to diagnose a problem and give as much info. as possible, it has most certainly not been left like it.

Will certainly get the flue checked out as the house is about 8 years old and there hasn't been a problem before now or with any of the other houses with the same set-up as mine in the street. Something's obviously failed somewhere in the system.

Tony - I appreciate that I am not qualified but I wasn't aware that changing the pressure switch was potentially dangerous. I wouldn't interfere with any of the 'gas' side of things of course but a couple of wires, a flex-pipe and a screw didn't seem to me to be too much of a hazard.

With regards to me taking advantage of British Gas - well I am more than happy to pay professionals to do what they do best, £40 labour for the air switch, I have no problem with that at all, but being quoted £80 for a pressure switch (which I got for £15 delivered and retail) is, I feel, not me doing the advantage taking. Had it been £100 labour and £20 for the part I would've been less likely to have done it myself.

Thanks again guys, don't worry, I'll get it sorted professionally.

 

[Agile]

In your case I would recommend a local independent as BG will not take well to a faulty flue installation.

You may think that replacing the APS was totally safe and on your boiler its outside the combustion chamber.

However, the normal interpretation of "working on gas" is not just a gas pipe but the "gas train" which is the gas valve, burner, combustion chamber, fan, flue and all the safety devices. The APS is one of the safety devices!

Calling BG to come and identify the fault free of charge and then trying to fix it yourself seems to me to be taking advantage of them. We always charge to diagnose faults and then its up to the owner how they repair it. Of course we usually repair it but thats their perogative.

If we made free diagnostic visits then we would have a full time job with no income!

Tony