Potterton Profile 80E intermittent firing

[Chris_Essex]

I am writing in the hope that someone can point me in the right direction with a boiler problem.

I have a 12 year old Potterton Profile 80E which my Corgi plumber tells me is in good condition.

It has always been serviced regularly but recently it's had an intermittent problem when firing. Most of the time it's fine, but occasionally I can hear the fan turning on for a few seconds, then it goes off, comes back on, doing this several times until there is a click and it eventually fires.

The problem is that works perfectly whenever my plumber comes out, but on a couple of occasions recently it has taken 15 or so attempts to light.

It seems to happen whether the boiler is hot or cold and there is no obvious trend. My plumber has said that it could be one of several parts causing the fault and has mentioned in particular the pressure valve and the pcb as likely candidates, but he is obviously reluctant to purchase parts for us until he can pinpoint the problem.

The only other symptom, which may be unconnected, is that he found a load of powder on the horizontal "tray" under the heat exchanger (I think that's what it's called). He can't see any leaks though.

Sorry, I'm not very technical on gas matters but if anyone has experienced similar problems or can point me in the right direction I'd be extremely grateful.

Thanks guys.

Chris

 

[stevetheplumber]

sounds like a pcb to me but it one of those you may have to wait till it fails to be sure but if fan stops its more likly to be pcb rather than airflow switch thats assuming when it does run fan isnt noisey

 

[Chris_Essex]

Thanks Steve.

Excuse my ignorance, but can a faulty pcb cause an intermittent problem? Would a faulty pcb just not work at all?

Sorry, but as I said, I'm pretty useless with things like this!

And tell me the worst - how much do you think a new pcb is likely to cost?

Cheers
Chris

 

[newbie1]

pcb can have intermitent faults dont think they are the most expensive pcb out there so prob not as bad as some

 

[Puddle]

As said this is usually a pcb problem,when boiler starts,it does a self check to see if all ok,in this fault it thinks burner is already on and the stops boiler and the starts again,causing cycling as described,problem will get worse

 

[Chris_Essex]

Thanks for all the replies everyone - can't believe how quickly you responded!

Can I add one final symptom to the equation please.

We woke up this morning to find the radiators and water only slightly warm. It looks as if the boiler had fired but the flame then cut out. When we went downstairs the fan was running continuously but with no flame. The boiler was set at 5 but was only warm, it had definitely not reached its thermostat limit or anything like that.

I turned the boiler control down to zero then back to max. It fired at the second attempt. I returned the setting to 5. The flame died again after about 15 minutes and the fan continued running. I got it going again by the same procedure and it's been running fine ever since. This has happened on a couple of occasions previously - sorry, I should have mentioned it in my post last night. Also the fan sounds slightly noisy but it seems to be operating fine.

Is this still consistent with the pcb theory?

Once again, thanks all.

Chris

 

[Puddle]

Thanks for all the replies everyone - can't believe how quickly you responded!

Can I add one final symptom to the equation please.

We woke up this morning to find the radiators and water only slightly warm. It looks as if the boiler had fired but the flame then cut out. When we went downstairs the fan was running continuously but with no flame. The boiler was set at 5 but was only warm, it had definitely not reached its thermostat limit or anything like that.

I turned the boiler control down to zero then back to max. It fired at the second attempt. I returned the setting to 5. The flame died again after about 15 minutes and the fan continued running. I got it going again by the same procedure and it's been running fine ever since. This has happened on a couple of occasions previously - sorry, I should have mentioned it in my post last night. Also the fan sounds slightly noisy but it seems to be operating fine.

Is this still consistent with the pcb theory?

Once again, thanks all.

Chris

No this seems like another problem,not the pcb causing cycling
It could point to a sticking air pressure switch or fan running slow when it gets hot
Looks like you have two problems now,good way to start the new year

 

[Chris_Essex]

That's really not what I wanted to hear(!), but thanks again for the speedy reply.

Cheers
Chris

 

[oldplumber]

check the hoses to the aps, a v small hole or loose connection caused a similsr problem for me recently allowing the fan to run up then fire up the burner only to close down then start the cycle again. I only found the crack after buying a pcb, but i hadnt opened the sealed bag and got my refund, eventually.

 

[stevetheplumber]

you can test air flow switch wih a meter to see if its switched over when fan is running

 

[Chris_Essex]

My plumber did actually find a slightly loose connection in a red hose a couple of days ago. He thought that might have been the problem but the boiler started playing up again as soon as he walked out of the front door!

We took a gamble and our plumber installed a new pcb last night. It's early days, but so far so good. The boiler has fired first time ever since and I had a hot shower this morning! I'll report back in a couple of days once we have tested it a bit more.

Once again, thanks to everyone for your help. I'm so glad I found this forum.

Chris

 

[jcps]

Hi all,

I am having similar issues with my potterton 80E. Its been playing up for a while but has got worse. I believe its the pcb and also think the cold has made the pcb worse. Could this be dry solder joints?

Basically the boiler seems to hunt, and then if I hit the bottom of the boiler, it fires.

Is this definitely the PCB?

 

[Puddle]

that sounds like a loose connection or air pressure switch
When you say hunt ,what exacly does it do

 

[jcps]

Buy hunting, I mean that the boiler makes a series of whooshing noises until I hit it, then the whooshing stops and it fires.

Thanks

JC

Just to add further, the whooshing noise sounds to me like the boiler is hunting for the spark. If you look through the little window on the front, you cant see any spark jumping accros until I hit the boiler. When I hit the boiler, you can see the spark jumping across until ignition.

 

[Puddle]

Buy hunting, I mean that the boiler makes a series of whooshing noises until I hit it, then the whooshing stops and it fires.

Thanks

JC

Just to add further, the whooshing noise sounds to me like the boiler is hunting for the spark. If you look through the little window on the front, you cant see any spark jumping accros until I hit the boiler. When I hit the boiler, you can see the spark jumping across until ignition.

Does not sound like pcb,think as said,also check electrode lead not damaged good connection

 

[REDSAW]

Buy hunting, I mean that the boiler makes a series of whooshing noises until I hit it, then the whooshing stops and it fires.

Thanks

JC

Just to add further, the whooshing noise sounds to me like the boiler is hunting for the spark. If you look through the little window on the front, you cant see any spark jumping accros until I hit the boiler. When I hit the boiler, you can see the spark jumping across until ignition.

i find a 1/2lb rubber mallet best.

 

[jcps]

Thanks for the info; I was planning to take a more in depth look this weekend. However, there has been a development, this morning whilst the boiler was hunting, I hit it as normal but then a spark started to ark from behind what I think is the air pressure switch (red and black pipe connected to it) that is where the PCB is situated.

I turned it off straight away; I will have to look tonight when I get home.

Thanks

 

[REDSAW]

sounds like one we did the other week,
the fan is on its way out and when it goes it will take out the pcb too.
that was a £380 repair job we did on a baxi solo.

loose wire or contacts need looking for too.

 

[Chris_Essex]

Just to report back that the new pcb seems to have done the trick. We are warm again!

Once again thanks to everyone for your help.

 

[Puddle]

Just to report back that the new pcb seems to have done the trick. We are warm again!

Once again thanks to everyone for your help.

Thanks for letting us know how you got on,pleased it is all sorted

 

[jcps]

Hi there,

This was the PCB. I replaced the capacator c7 on the the board and its been working for three days now.

Thanks