We have had a new heat only boiler installed this January. Just recently when the central heating shuts off there is a loud bang, it doesn't do it every time, but I can't figure where the noise is coming from. The pump is in the airing cupboard along with 2 motorised valves. Any ideas please?
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Bang when central heating shuts off
- Thread starter rogerfromnorwich
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- 11 Apr 2022
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Pipe work not secure somewhere is possible.
On mine, it was a sticking auto bypass valve. I think I screwed it in and out a few times and that cured it.
Ours was a slightly different situation which took ages to solve as pretty much every other post talked about a bang when the CH shut off. Our system is a 3 port valve model with a separate 2-port safety valve for the Megaflo HWC.
We eventually worked out we had a build up in pressure at the Megaflo 2-port valve in CH only mode - HW was off. The wiring for the 2-port valve was connected to the tank thermostat. When the HWC dropped in temperature it caused the 2-port to open, triggering a pressure wave and a subsequent bang. Highly unnerving.
Eventually fixed by a local plumber who came up with an ingenious solution to connect the 2 port wiring direct to the overheat sensor on the Megaflo instead. So we are still protected but now have silence in the system! Phew.
We eventually worked out we had a build up in pressure at the Megaflo 2-port valve in CH only mode - HW was off. The wiring for the 2-port valve was connected to the tank thermostat. When the HWC dropped in temperature it caused the 2-port to open, triggering a pressure wave and a subsequent bang. Highly unnerving.
Eventually fixed by a local plumber who came up with an ingenious solution to connect the 2 port wiring direct to the overheat sensor on the Megaflo instead. So we are still protected but now have silence in the system! Phew.
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