Apollo 80B overheating hot water

[jimhartland]

I have an Apollo 80B boiler. The boiler is approximately 15 years old. At the moment the hot water is being heated to a scalding temperature. The central heating appears to be working normally.
I thought that the problem was a faulty thermostat on the hot water cylinder and I have replaced that but this appears to have made no difference.
I realise that this may not be a boiler problem at all but can someone suggest what to try next, or perhaps it is a known problem.
Many thanks
Jim

 

[croydoncorgi]

3-port or zone valve probably stuck open, so you're heating the water all the time you're heating the rads. If the CH is OK and the boiler is not complaining, there's probably nothing wrong with the boiler (except age - 15 years is about the MINIMUM for an Apollo and it was cheaply-made to begin with. Start saving up!)