CH works fine but when hot tap is opened water begins to heat up, but when 4 or 5 lights on panel are lit boiler shuts down and water goes cold. Then it comes back on and cycle repeats itself, all the time emitting a high pitched whistle (but only when CH is on). I have changed the overheat thermostat, removed and cleaned the diverter valve and changed the 3-way spring kit. None of this has solved the problem. Any ideas please?
Ariston combi microgenus 23 HW cuts out
- Thread starter cowboydave
- Start date
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the boiler shuts down just for a second or two then fires up again and repeats for as long as tap is open
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thanks anyway
i have a microgenus 23 mffi ( would not have another ). was having a similar problem you are having. after many strip downs i found that the electrodes were corroded and causing the flame rectification circuit to fail when the boiler flame size reduced due to the modulating action of the boiler when calling for hot water, as the flame size reduces the rectification circuit is lost. then when the boiler relights it is at full flame until it modulates down again then circuit broken again and so on. all i did was clean the electrodes and the boiler is working as it should. this is not a job you can do yourself unless you are CORGI REG because it means removing the sealed cover to the combustion chamber. You can look through the inspection hole whilst the burner is on and look at the electrodes to see if they look corroded. As i say they were in my boiler and looked paticularly worse on the ends. central heating worked ok and i think this was due to the flame not reducing in size, therefore not causing the rectification circuit to be lost. Hope this helps.
Andy.
Andy.
Your primary heat exchange is blocked. i have had this on a couple of these already.
Drain the boiler and undo to 2 connections on the primary heat exchange and remove the thing. You will probably find the 22mm fibre washers on the heat exchange have been narrowed down and this will be effecting the flow. i once removed 1 and it had been narrowed down to about 8mm so no wonder the boiler kept overheating. your heating system may be due a good clean out if this is the case.
Drain the boiler and undo to 2 connections on the primary heat exchange and remove the thing. You will probably find the 22mm fibre washers on the heat exchange have been narrowed down and this will be effecting the flow. i once removed 1 and it had been narrowed down to about 8mm so no wonder the boiler kept overheating. your heating system may be due a good clean out if this is the case.
thanks to everyone it was eventually the electrodes that were corroded.
i can stop pulling my hair out
Dave
i can stop pulling my hair out
Dave
Ok, you may have cured the flame sensing problem, but did this cure the " whistling " noise ? i don't think it would have been anything to do with this. As micky p says it sounds like the heat exchanger also requires cleaning out and the seals condition checking. Blocked heat exchanger would cause overheat lockouts and cause lower flow rates.
i forgot to mention that i did clean out the heat exchanger checked the washers but they are rubber there was just a bit of scale that washed out under the tap but the whistling has stopped
once again many thanks
dave
once again many thanks
dave
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