Potterton suprima 50 green LED flash thermistor fault

Hi,

I have a new PCB installed in potterton about 3 years ago. It the newer type with more sofisticated electronics than the original with all its dry solder joints etc.
Its worked really well for a couple of years but now the boiler keeps tripping off with the green LED flashing when the heat is still being demanded from the hot water tank. Im pretty sure the tank temperature has not yet been reached and so I am currently guessing that its the thermostat on the boiler that is somehow being misread.
I have pulled the thermostat out and left it dangling in the boiler space, and now it works fine such that the heat demand is satisfied by the water tank and the boiler then shows a steady green/red LED which is all okay (heat stisfied).
I have measured the thermostat resistance and it reads fine and certainly between the 40Kohm and 2 mega Ohm resistance specified. Its also been replaced to little avail.
So my suspicion is the PCB, but at £150 a time, its a lot of money.
Does anybody have experience of this type of fault and what the resolution was?

thanks

Guy

Does the boiler cycle ie on for say up to 3 mins then off and repeated? If so definately the pcb......

guydean said:

I have a new PCB installed in potterton about 3 years ago. It the newer type.

steady green/red LED which is all okay

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Explain more

Is the pump working properly...could be running very sluggishly and not getting the water away from the boiler quick enough...

or there could be a restriction some place...

Which PCB do you have...does it have a square reset or a round one?? 1 led or 2??

Sounds like you have the same problem as me - continous store demands for heat but the boiler anti-cycles because its own temperature is satisfied.

If your asking about PCB version 5102160 I've changed mine (reconditioned) and it didn't help, neither did changing the thermistor or boiler pump.

I too ran with the thermistor out but got a lot of kettling and the front panel got very hot so I put it back.

Be interested to know what the solution is.

Trumpet said:

5102160 I've changed mine (reconditioned) and it didn't help

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I wonder why this PCB was originally replaced and sent for reconditioning?

Perhaps fitting a 'new PCB' would be the answer. It certainly cured the ones I've been to.

guydean said:

I have pulled the thermostat out and left it dangling in the boiler space

Click to expand...

Probably not a good idea Maybe you should get a new heat exchanger ready

I wonder why this PCB was originally replaced and sent for reconditioning?

Perhaps fitting a 'new PCB' would be the answer. It certainly cured the ones I've been to.

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You may be right but so far three engineers have charged me for them to guess whats wrong - I can guess myself for free

If the problem is the old style 5102160 PCB (which mostly suffers from lockouts) and the latest version will fix it garantueed then I'm happy to pay someone to come out and do it, but £180+ for another guess is too much!

Trumpet said:

I wonder why this PCB was originally replaced and sent for reconditioning?

Perhaps fitting a 'new PCB' would be the answer. It certainly cured the ones I've been to.

Click to expand...

You may be right but so far three engineers have charged me for them to guess whats wrong - I can guess myself for free

If the problem is the old style 5102160 PCB (which mostly suffers from lockouts) and the latest version will fix it garantueed then I'm happy to pay someone to come out and do it, but £180+ for another guess is too much!

Click to expand...

Only if its the PCB thats the fault.... can be lost of other things too ie Gas valve, APS, spark electrode or the lead.