chaffoteaux britany combi 80

[whatarascal]

Hi all I have a chaffoteaux britany combi 80

the boiler is producing hot water but the water is delivered at full temp for 15 seconds then at a lower temp for 15 seconds and so on and so on. When the central heating is turned on the boiler produces better results but still not a constant temperature. With the case cover "part 311" removed the boiler runs at full power and heats water to correct temperature. The water pressure is ok and its unlikely that the gas pressure is down.

Some of you may think I am meddling with stuff that I shouldn't but after having a central heating expert call and tell me to get a new boiler because this one is leaking, "at the top was his terminology" I decided to find this leak, the heat exchanger looks in very good condition and certainly has no leaks. So does anyone have any ideas as to the cause of this problem?

Regards

Whatarascal

[Ed Sirett]

The over-wheming cause of HW problems in combis is limescale. These boilers are not the most robust models. There is usually a trail of corrosion caused by leaking, in the more severe cases the parts are wet. In the worst case the boiler is dripping water out of the case.

You could of course have other problem which are causing the problem, the casing removal feature is interesting.

Measuring the gas pressures to the burner would be the next step. They should be as the manual states.