Worcester Greenstar danesmoor 18/25 cutting out after three minutes

23 Oct 2016
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United Kingdom
Hi I have just bought a house with a Worcester Bosch greenstar danesmoor 18/25 boiler (oil) it has been working great however now cuts out after three minutes of operation from cold, it does eventually cut back in after about 15 minutes when it will run again for about three minutes and now instead of hot water all I have is tempid water in both the heating and hot water systems. When it does cut out neither of the lockouts on the bottom of the control box trigger and the lockout on the burner is not lit (and does not do anything if the reset button is pressed) in addition the pump for both the hot water and central heating continues to pump the tempid water around ......any ideas anyone?
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Are you sure the central heating pump is actually working? It sounds like it's cutting out on the thermostat, which suggests that the boiler thinks it is up to temperature
the pump did seem sound to be running ok and the valves on the water and central heating seem to operate as I expected as the pipes felt warm perhaps the pump motor is running but not driving the water through the system as the pipes into the pump do feel pretty hot
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Ball valve stuck in header tank, system empty, rads bled? Pressurised system ? System full ?
Had a good go at the system tonight ball valves in header tank all ok, fired up system and bled the pump and got lots of air out and boiler is now cycling in and out much more frequently, hot water now seems ok but central heating still not great so am going to try bleeding it again tomorrow. I do suspect the pump may be worn as when water heater and central heating on it seems to put more emphasis on hot water that heating despite both valves being opened and both being fed via the same output from the pump however will bleed first before spending £100 on a pump. Appreciate the advice guys!

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