Potterton Prima 30F fault

[fisherproperties]

Hi All,

Please can someone shed some light on this problem...

Firstly I'm not Corgi registered myself, I'm a professional landlord and one of my tenants boilers has failed. I've been working with my gas man to get this boiler fixed but we're both stumped!

We have a Potterton Prima 30F about 14 years old. It's got a fault where it won't light. The fan runs for 2-3 secs, the pressure switch clicks, then the fan slows down and stops. 10 seconds later it repeats. It just won't light the boiler at all.

So far we (or rather my gas man with me watching!) have changed both the fan and pressure switch. We've checked all the tubes, flue and gas pipes are clear. I've checked over the PCB (I used to be an electronics engineer) I resoldered some joints as a precaution. I've gone over the electrical side with my meter, and everything seems fine. A new PCB is in the region of £140 and his supplier won't give him sale-or-return on it so I'm reluctant to buy it after spending so much on it besides I'm fairly sure this ones fine.

We unplugged the gas valves and it does exactly the same and my gas man has said this would prove it's not these either.

Now here's the weird bit... it works much better with the cover on, probably 50% of the time it will light. But take the cover off (outer cover not on the heat exchanger) and it won't light at all. I know there's a seal around the cover and that seems fine too. Sounds to me like an air pressure kind of issue.

As I said I'm just helping out here, my corgi training consists of watching my gas man doing endless landlords certificates for me but I do have a bit of experiance with boilers. He'll be doing all the work for me.

We're a bit stumped

Anyone got any ideas?

Thanks,

Trevor.

 

[baxpoti]

You may find that the end of the flue is rotten. Causing vitiated air to be recirculated. But it's normallly a PCB.

 

[baiterhater]

I have fixed a ton of primas with that fault and sorry to say its always the board, if you can drop it down you will see one of the relays dropping back.


j

 

[nicknox]

PCB

 

[fisherproperties]

I have fixed a ton of primas with that fault and sorry to say its always the board, if you can drop it down you will see one of the relays dropping back.

Thanks for that, can you explain what you mean? I've completely removed the board and resoldered it. The PCB has two relays on the board. I have swapped them around in case one was faulty, but the fault's still the same. It doesn't prove the PCB's not faulty though.

I'll check the flue more carefully too just to rule it out... perhaps I'll have to get my hand in my pocket again for a new board

Trevor.

 

[mickyg]

pcb(very common) or dodgy flue (also common but doesn't always cause a fualt condition)

 

[twgas]

pcb, if its the flue rotted the gas will light for a few seconds then go out, the fan wouldnt stop before ignition.

 

[Agile]

If you really are a professional landlord then I am surprised that your professionalism does not extend to buying new spare parts for your boilers?

If you really had a professional gas man then you would be paying him £30-£40 per hour and wasting two hours of his time would buy a new PCB.

Do you know his CORGI registration number?

Tony

 

[fisherproperties]

Hi Tony, thanks for your comments...

If you really are a professional landlord then I am surprised that your professionalism does not extend to buying new spare parts for your boilers?

Yes I am thank you. I do carry some spares (like the fan and pressure switch we have already changed) but with 40-odd boilers of all makes and models under the sun it isn't possible to carry everything.

If you really had a professional gas man then you would be paying him £30-£40 per hour and wasting two hours of his time would buy a new PCB.

Well we'd discounted an electrical problem because the boiler works half the time with the cover on, but not at all with the cover off. To me that doesn't sound electrical, however thanks to the helpful people here I'll change the PCB and report back.

Do you know his CORGI registration number?

Yes thank you.

Trevor.

 

[Agile]

CORGI ceased being the registration body for Gas Engineers three weeks ago and your man should have renewed his registration with the new registrar.

The simple fact is that your boiler works half the time! Thats likely to be the PCB.

Your man sounds as if he is a dangerous nupty if he does not know or is unable to explain to you that it has different air pressures with the case on and off and is probably designed NOT to work with the case off.

We dont give advice on gas matters on the open forum but there is a special area of this site for registered engineers. Why does your man not ask us there or is he unable to use a computer?

Tony