Boiler overheat keeps tripping

I have a Baxi Solo WM70/4PF which is fine when its working. The problem is that the overheat button keeps tripping & shutting the thing down....very irritating when you want a bath/shower & discover there is no hot water!!!

The problem is very erratic & sometimes it will go for days without happening & then will happen twice in one hour. Each time I reset the trip button & off we go again. The hot water is set to 60C & the boiler water temp is set quite low (just under 2 out of 4). It seems worse when the heating isn't on.

At the moment the pump switches on & off with the boiler & I wonder if its a heat build up within the boiler once the water stops circulating. I've thought about trying an off-delay timer to keep the pump running for a few mintues after the boiler swtiches off......

Any thoughts.....its driving me nuts!!!

The pump should be driven by the boiler to provide any over run.

Either the pump is wrongly connected or the over run on the PCB is not operating.

The boiler stat circuit could be faulty too. Your setting is about right if it is working properly.

Tony

Thanks for that Tony.....

We've been in the house since 2000 (it was built in 1993) & its always had a tendency to do this but has been much worse recently which may indicate something is dying on a pcb somwhere......

Any thoughts on how to check the over-run & the boiler stat circuit??

We have a few Baxi Solos on the patch that behave similarly and trip out on the overheat unpredictably. Can't say we have ever really had the time or money to throw at them to deal with the problem properly, but we had always assumed it was something to do with their heat exchangers getting hot spots as they aged and circulation got a bit restricted.

A pump overrun may be just the job to keep em a bit cooler. Its odd as sometimes they run happily for months and months..and just when you think the problem has gone away..

Sorry I can't shed much light..but you are not alone. Baxi technical may be worth a call

Alfredo