Overheat thermostat tripping - EuroCombi

[AdamWylde]

I have a Eurocombi SX 20 MFFICE and added a radiator about a month ago followed by a dose of Protex sludge remover, followed by inhibitor.

All has seemed fine for a couple of weeks but now the boiler has a couple of odd symptoms....

1. It has appeared to overheat 4 times today and tripped the overheat thermostat so I have to reset it manually. It tends to do this when I'm not looking so I don't know if it is really overheating but I am pretty sure its a central heating issue not hot water.

2. When the boiler is running at full burn there is sort of rattly/fast clicking sound from the combustion chamber.

Any ideas would be appreciated.

Thanks

Adam

 

[ChrisR]

Overheating: might be many things. But with CH off, try the HW a few times. Does the boiler ever stay on after drawoff? (ie when it shouldn't.)

Do you have trv's on all your rads?

 

[AdamWylde]

Chris

No it doesn't seem to run on when drawoff of hot water is stopped, and I'm 90% certain it has tripped when we have been out of the house...

I had never really thought about it before but we do have TRVs on all radiators (I know thats bad but it was like it when we bought the house).

I've just opened the TRV fully in the room where the thermostat is so I'll see how we go. Strange though that its only been doing it recently if thats the answer. In fact the system didn't have a thermostat when we moved in - I added one - it used to shut off based on the temp of the water circulating I guess, so I would have thought that it would trap an overheat of that kind anyway.

Thanks

Adam