Prima 100 F overheat thermostat

[elmsoft]

My Potterton Prima has given good service for 25 years but recently the overheat thermostat has been cutting out while the main boiler stat is set at little more than half way. Quite a nuisance
According to the manual no adjustment is provided but I wonder if the mechanism gets "tired" and can be replaced.
Maybe it is time I thought about a new boiler but I am reluctant to splash lots of cash to solve what should be a minor issue.
Anyone had similar issue?

 

[stardanny]

Check your pump is running ok.

Try turn up speed by one and see if that stop overheat trip.

Daniel.

 

[Phill Peck]

Over heat stat can become more "sensitive" over time.
Could be another issue though pump etc.

You could consider replacing your boiler and would see around (iirc the efficiency of your boiler) 25-30% saving on fuel. But I suspect your boiler can be easily repaired.

 

[elmsoft]

Thanks for the input.
Wondered about pump speed and blockages etc but supposed "slow " water through the heat exchanger would still trigger the primary boiler stat first , all things being equal.
If I do bite the bullet and go for a new boiler, any recommendations for a suitable swap?

 

[jeff the gasman]

The main boiler stat is a common problem on these. They go out of calibration.
The overheat stat is probably just doing its job
Also flow thermostat sensor sometimes comes away from flow pipe. Top left.