Potterton Combi Bolier

[barnet boy]

I have a 6 year old Potterton Combi 80 boiler.
In the summer it is OK. However, in winter it tends to 'lock out' at least once a day.
When this happens it does not always reset and so I have to turn off the central heating switch, run a hot tap and then switch the boiler back on. This normally works.

I have had both the modulation circuit board and boiler overheat thermostat replaced with no success.

Any suggestions?

Cheers.

[buildersmate]

Boiler lock-out generally occurs when the water temperature rises too high. But you've changed the overheat thermostat. Could be scale on the inside of the heat exchanger - impacts the ability of the boiler to transfer heat out into the water flowing past. Do you live in a hard water area? Has anyone suggested descaling the water with a proprietary chemical, then refilling with inhibitor. Probably something you could do yourself.

[barnet boy]

Thanks for the reply.

Although I live in the hard water South East, I have a Tapworks water softener which treats all the incoming water before it reaches the boiler, (except the kitchen mains).
Would it be worth having the central heating water temp sensor changed?