Alpha 240e cycling on and off when supplying CH and/or DHW

[k3ys3r_soz3]

Hi

I'm having issues with my Alpha 240e boiler and would be thankful for any advice. (See this link for previous problem which resulted in diverter valve being replaced and problem solved - thank you to all that helped! //www.diynot.com/forums/viewtopic.php?t=116789&highlight=)

We now have the boiler cycling on and off when ask to supply DHW or CH.

For either, the boiler will fire when it is supposed to (i.e. triggered by CH timer or hot tap being turned on) and supply for around 30 seconds to a minute. Then the boiler turns off - as if the CH timer had ticked off or the hot tap had been shut, no warning lights showing, water coming from hot tap starts to cool off. After a few seconds it relights and water gets hot again after a little while. (Apart from one or two times I noticed it take a few clicks to relight.) This then happens again, and again.....

Apart from the radiators being rather luke-warm and the shower being alternately hot and cold as you're in it, I'm guessing it's not doing the boiler any good constantly relighting!?

It does seem to 'cure itself' of the problem intermittently and we get a nice warm house / steady temp shower DHW is properly hot prior to the boiler turning itself off too.

Any ideas? - or anything I can try to aid a diagnosis?

 

[gas4you]

Replace the primary/ch ntc

 

[k3ys3r_soz3]

Thanks for your help. The problem does seem to be rather intermittent - would that still be the ch ntc? If so, do you need to drain down the ch system to replace?

 

[gas4you]

Just drain the boiler. I tend to avoid using the ch isolating valves under the boiler, as they will usually leak and cost around £50 each to replace