Problems with Alpha 280e combi boiler

10 Aug 2009
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United Kingdom
I have an Alpha 280e combi boiler. The boiler is currently set for DHW only, when I open the hot tap, the boiler fires up, hot water comes out of the tap at pressure. The problems start when I close the hot tap, the boiler fails to turn off and it continues to run, also the neon DHW light remains lit. Eventually the CH pipe under the boiler heats up. To solve this at present, after running the hot tap we switch the boiler off till we need hot water again.
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sounds like the dhw micro swith is faulty or the push rod is not retracting into the pressure differrential valve correctly cuasing the demand for hotwater to remain on
Thanks gaspro1981 for the speedy reply, plumber came around this afternoon and as per your post found the push rod was stuck. He changed the DHW flow valve and everything is working OK. The whole job lasted about 1/2 hour. Again many thanks for the speedy and correct diagnosis of the problem
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