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

On Wed, 19 Sep 2007 07:08:28 -0700, whatarascal wrote:

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

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.

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html