Potterton Prima F 60F - Air Pressure????

Silu · 26 Feb 2007

I have had a problem with my Potterton Prima F 60F. the problem is that when the boiler is cold, it won't fire up. The fan starts to whirl for about 30 secs then switches off. This cycle keeps repeating itself. The solution i have found is to either blow down or pinch the red pipe. The boiler then fires up and lasts until a couple of hours of none use (i.e. when all water or ch has been satisfied and the boiler hasn't fired for that time), typically overnight or when it is cold.

The fan has recently been replaced (say 6 months) and up until this time has been working a treat. Some suggested cleaning through the venturi pipes on the elbow, which I have done but they were clean as a whistle anyway. Others suggested I changed the air pressure valve, but looking at some previous links this did not work for them!

Has anyone had similar problems, and if so, how did they fix it?

gas4you · 26 Feb 2007

tried tapping the air pressure switch whilst fan is running? How did you clean venturi? with a compessor? any splits in aps pipes?

Silu · 26 Feb 2007

gas4you said:
tried tapping the air pressure switch whilst fan is running? How did you clean venturi? with a compessor? any splits in aps pipes?

Theholes are quite big, one I could see through the other because of the bend i had to pass some thread through, then used a compressed air jet (for cleaning keyboards etc). felt the jet of air come through and beleive they are not blocked. The second thing you say, I ghave tried tapping the air pressure switch and still nothing? The thing I can't get my head around is why if you blow down the red pipedoes it work, or by pinching the red pipe (i.e. starving the air) does it work?

Appreciate any suggestions (even if I can't carry them out, I have a plumber friend who will but even he is stumpt at the moment - trying to get hold of Potterton).

gas4you · 26 Feb 2007

Its all to do with positive and negative pressures. Does the boiler fire with the case off? Was the flue disturbed and not put back correctly after the fan replacement.

I would also suggest checking fan again. Golden rule no1, never assume a new part is working correctly!!! It sounds as though there is not enough pressure to activate the aps.

Silu · 26 Feb 2007

gas4you said:
Its all to do with positive and negative pressures. Does the boiler fire with the case off? Was the flue disturbed and not put back correctly after the fan replacement.

I would also suggest checking fan again. Golden rule no1, never assume a new part is working correctly!!! It sounds as though there is not enough pressure to activate the aps.

The boiler only fires with the casing off, if I blow or nip the red pipe. Not sure if the flue was disturbed and take your point about the fan. I will get the same plumber back.

Thanks for the suggestions.

gas4you · 26 Feb 2007

I realise its hard for you to tell in this situation, but if it fires with case off usually points to venturi blockage of some kind. I take your point about the venturi looking clean. Another thought, are the aps tubes connected correct way? Have you blown down these?

Silu · 26 Feb 2007

gas4you said:
I realise its hard for you to tell in this situation, but if it fires with case off usually points to venturi blockage of some kind. I take your point about the venturi looking clean. Another thought, are the aps tubes connected correct way? Have you blown down these?

The APS pipes are connected in the right way, well that is to say that they are how they were, red to the bottom pipe and white to th etop of the elbow (venturi) as I beleive th emanual states.

What I can't work out is that by taking off th ered pipe from the venturi, and doing nothing (i.e. blowing or nipping) the boiler fires! If however I recoonect the red pipe whilst the boiler is still whirring, the boiler stops! So if the red pipe acts as an air intake, why does it work disconnected and not connected; as the fan does generate air through the venturi, and to me whatever little pressure generated through the fan/venturi, must be more than that generated disconnected? Or am I totally misunderstanding how all this air pressure thing works?

By the way, if I leave the red connected and disconnect the white, the boiler fails to fire????

gas4you · 26 Feb 2007

Tried changing aps pipes round, just to eliminate all possibilities? Are the 3 wires to the APS connected correctly?

Silu · 26 Feb 2007

gas4you said:
Tried changing aps pipes round, just to eliminate all possibilities? Are the 3 wires to the APS connected correctly?

Haven't yet, but can give it a go, i take it, it won't blow anything (including me)? I have checked the three wires and they look okay and in accordance with the manual (all well seated).

gas4you · 26 Feb 2007

Changing pipes around will either work or make no difference. Just don't blow any compressed air into aps!!! maybe aps sticking after all?

What does plumber who fitted fan make of all this?

Silu · 26 Feb 2007

gas4you said:
Changing pipes around will either work or make no difference. Just don't blow any compressed air into aps!!! maybe aps sticking after all?

What does plumber who fitted fan make of all this?

I've yet to call him. He fitted the boiler about 9/10 years ago, but I beleive he is demi retired now and I beleive his Corgi registration has expired, hence I have been talking with a friend of mine who is Corgi registered. He was trying to get hold of Potterton to ask their advice.

tassy · 26 Feb 2007

The Pcb is faulty if the fan starts to whirl for about 30 secs then switches off.

gas4you · 26 Feb 2007

over to you tassy. I'm out of ideas

Silu · 26 Feb 2007

tassy said:
The Pcb is faulty if the fan starts to whirl for about 30 secs then switches off.

gas4you - thanks for your help and suggestions.

tassy
Having timed it, it's actually about 15 seconds (if that makes a difference), But if it is the PCB why does it start if I disconnect the red pipe?

waynedance · 2 Feb 2009

I know this is an old post but i have the same problem with my prima f 30 f boiler.

If i pinch the red pipe it will fire up, it will keep firing up until the boiler goes cold.

What did you do to fix your boiler?

Thank you.

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Potterton Prima F 60F - Air Pressure????

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