Hawk II combi no Heating

I have an aging ferroli Hawk II combi boiler and it has developed a fault. It had a loss of pressure, which it often does, but now I have refilled it no heating. The hot water is OK and the Pump is working but all that happens for heating is that the boiler fires for approx

30 seconds then goes off for 10 minutes and then repeats. The radiators are very slightly warm. Any help and ideas would be appreciated Thanks
Reply to
sjones
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In message , " snipped-for-privacy@scannex.co.uk" writes

Air lock ?

Reply to
geoff

Pump problem (despite what you say). Air locks. detached impellor. Temperature sensor.

Main flow/return isolator(s) closed.

See SealedCH FAQ about the pressure.

Reply to
Ed Sirett

know why. The day before I undid the screw on the outside of the pump and I can hear the pump stop, if i push in the hole with a screwdriver it starts. Bleed the heat exchanger and found no air. If I listen at the rads I can hear the pump pushing water so if it is the pump what else can I do to confirm this. The mother board has diagnostic LEDs to show whats going on and when working and power applied some should light, however I have never seen any of them lite. Checked temp sensor and 1K which corresponds to cold water in Rads, CH overheat thermostate closed. I think it could well have needed venting, which I did but never found any air. Just hope it keeps going Thanks

Reply to
sjones

I think I will try and replace the pressure release vent valve which is causing the loss of pressure, how easy is it to replace. Thanks

Reply to
sjones

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