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. I phoned Alpha and asked for a Service Manual. They readily agreed and an envelope arrived yesterday - unfortunately just a user guide which tells me nothing much beyond the fact that is uses gas to heat water. Certainly no use for diagnostics. I recall that we've had to replace the/ a PCB a few years ago, at 120GBP or so. But presumably the failure could be of a thermostat, or the divertor valve? Simple diagnostic steps anyone? Thanks Kingsley