Potterton Overtemp Tripping

[Davewm1]

Morning all.
Can anyone help me with a bit of advice.

We “inherited“ a Potterton Prima 60F boiler (which we were told in 2013 was 3/4 years old). It turns out after checking Serial number with Potterton that it was manufactured in 2003.

Had it regularly serviced but a few weeks ago it failed to come on in the morning. I found the over temperature reset - pressed it and it restarted.

Failed several more times so the Service chap checked it over when he came and said he though that the flue was the problem.

Normally I have hot water and heating on from 7.00am to 9.00am and then hot water 4.00pm to 6.00pm with heating 4.00pm to 9.00pm.

I changed the timings and had hot water on 5.00am to 7.00am. Today, for example, hot water worked ok but no heating when we got up - had to reset again.

After service it has still continued to fail and the chap is currently looking to quote us for a replacement due to the age!

What I can’t understand is that it will work ok for a longish period then it will go off on the room stat but (now a couple of times a day) it has to be reset for it to restart.

Is there anything else anyone could suggest as to the cause of the problem? Could it be a faulty Boiler thermostat for example?

Any ideas would be welcome as sods law it’s happening on the coldest days of the year.

Kind Regards

David

 

[cross thread]

Could be as simple asa faulty o/h stat.

 

[Davewm1]

Thanks “cross thread” I’ll have a look how much they are. Would you happen to know if you can test them or is it just a matter of replacing the current one to see if that then works?
kind regards
David

 

[ianmcd]

your boiler uses a Ranco stat , never seen a faulty one that can be reset, they are a liquid filled Phial and capillary tube, if the capillary was leaking you wouldnt be able to re-set it, you have a circulation problem

 

[Harry Bloomfield]

What I can’t understand is that it will work ok for a longish period then it will go off on the room stat but (now a couple of times a day) it has to be reset for it to restart.

Is there anything else anyone could suggest as to the cause of the problem? Could it be a faulty Boiler thermostat for example?

I would suggest it is probably a poor flow through the system, or the boiler, causing it to over-heat.

 

[Deleted member 267285]

What I can’t understand is that it will work ok for a longish period then it will go off on the room stat but (now a couple of times a day) it has to be reset for it to restart.

Room stat or overheat stat or both?

 

[Davewm1]

Hi Chris. It will cut off on the room stat as normal but then will not restart and I have to press the overtemp reset button. It then starts.

 

[Johntheo5]

Does the boiler do a pump overrun after shut down? Some boilers had/have a separate overrun stat that keeps the circ pump running until the temperature falls, maybe this is the problem?.

 

[Deleted member 267285]

Could be the overheat stat, but if @ianmcd has never seen a faulty one, then chances are it isn’t. Check for circulation issue as Ian states.

 

[gas112]

After demand has gone check that the pump continues to run for several minutes afterwards. pump over run stat may have gone