Sealed system problem

  • Thread starter eddiescully
  • Start date


I turned on my oil fired heating for the first time in 2 months and the boiler fired up and all rads got hot. I switched it off and later turned it on again and the boiler fired up but no rads were getting hot.

The boiler had cut out on temp and pump was running, and the flow and return were hot from boiler but not when it entered my hose from the boiler shed.

The Pump is running and pipes from boiler still hot.

Any thoughts?
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Cant be sure what model its a grant standard efficiency boiler, open flue boiler and it has a riello burner. Could it be that the water pressure got a bit too low and it created an airlock in the pipework between the boiler and the house?
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It went down to half a bar cold. It has one of them filler valves with a pressure gauge on it, not too sure how to top it up, the valve has a black knob at the bottom and a brass bar at the top that you can turn it in or out with a flat head screwdriver.
1 May 2010
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United Kingdom
Sounds like the pump to me even though its running, what tests have you done to make sure of this?


I unscewed the centre nut where you blead the pump and i check was the impeller spinning with a screwdriver and it was ok

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