Potterton Prima 80 cutting out

Hi all,

We have a problem with our old Potterton Prima 80.

It runs fine for a few hours and then just randomly turns off (even if the room stat is demanding it to be on). Only way to get it to come back on is to turn the mains power off and on again. The reset button does NOT pop out.

Sometimes it will go straight back on after I cycle the power, other times I find I have to leave it for an hour or so before it decides it's ready to fire up again.

Only seems to happen in cold weather, presumably because it gets more continuous use then. It's situated in the (cold) garage if that makes a difference.

Turning it down to 2.5 on the thermostat seems to alleviate the problem but this seems to stop the hot getting up to temperature.

Reading around, given that it's fine when it's running (no fan or ignition issues) it seems the likely culprit is either one of the thermostats (boiler or overheat) or the PCB.

Does the fact that the reset button does NOT pop out give us any clues?

Thanks,

Rob

The only clue it gives is that it is not caused by the o/h stat operating.

But it can be many other causes many gas related.

Consequently you would be better getting a gas registered engineer to diagnose the fault properly.

That boiler is pretty old now and rather past the use by date! A saving of about 22% could be expected with a modern condensing boiler. Many engineers would be reluctant to repair it and try to persuade you to have a new boiler fitted.

Tony

Thanks Tony.

I'm well aware that getting a registered engineer out to repair it will probably be a non-starter as no one touches old boilers these days and unfortunately I don't have a spare £2-3k burning a hole in my back pocket at the moment! Even if I did it would take a long time to see that back even at 22% saving.

If it was banging or not igniting then I'd certainly be looking at replacing it one way or another but as the boiler works fine when it's on I feel I should at least try and figure out if it's something simple like a duff stat.

So would the reset button only pop out of it was the overheat stat tripping?

Could it be the PCB? Might a refurbished one be worth a punt at £50?

Rob, it's unlikely to be overheating. From what you tell us it doesn't sound a particularly hard fault to fix. It may be pcb, but it could be other components causing your fault. I wouldn't guess at a pcb. Could I suggest a one off fixed price repair by BG as a solution. Ignore the sales patter. They will be able to fix it for you, if you can't get a local independent. Good boiler and worth spending a few quid on.