On Fri, 20 Oct 2006 14:00:39 +0100, Kingsley Sawyers wrote:

Hi
Hoping for wise words in diagnosing the problem with my Alpha 240E combi
boiler.
Supply to the CH seems fine, in that those radiators which are not locally
thermostatically controlled are getting warm.
The problem is with the domestic hot water. Looking at the boiler when a
tap is turned on, the progress is;
- run a tap
- boiler detects the water demand and fires the burners
- water at the tap starts to flow warm
- after perhaps 20s (variable), burners cut out (no warning/ indicator
lights first)
- after another short delay, the burners usually cut in again
At the start of the week, it was possible to get a constant burn for DHW to
a downstairs tap by asking for quite a strong flow, i.e. tap nearly full on.
At lower flow rates it would burn-cycle. Now even that is gone; the water
isn't getting hot regardless of the flow requested.
Flow to the bathroom upstairs is now hopeless. Not only is the flow rate
much reduced from "normal", it barely gets above lukewarm such is the burn
cycling problem.
I've had my local CH technician out - the boiler was serviced, and he's had
the heat exchanger off to check for scale etc. - very clean.

....um ... this is where I want to ask some awkward questions.

There can be no scale near the inlet and outlet whilst deep inside between
the plates there is trouble.

--
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
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards