Pressure loss on a combi Boiler

Discussion in 'Plumbing and Central Heating' started by zinnia48, 11 Apr 2007.

  1. zinnia48

    zinnia48

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    I am a bit confused about the workings of a combi boiler, which i hope someone can enlighten me. When a combi boiler loses pressure on the central heating loop, which is closed, it has to be be repressurised. I can fully understanfd that, howegver when the pressure drops to about 0.5 the hot water part of the combi fails to heat the water for the kitchen, etc. Why is that, i would have thought the hot water operation was independant of the ch pressure, working like an old fashioned ascot heater. Can someone explain this , thanks
     
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  3. Rob

    Rob

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    Low water pressure switch. prevents dry fire
     
  4. newcomers

    newcomers

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    the water that heats the hot water is the same water that is in the ch system, so if that is low, then it will affect the heating of your hot water.

    Basically, if there was no water in the ch system, then you would not get hot water at your taps, as it is this water which heats your hot water taps
     
  5. zinnia48

    zinnia48

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    Thanks for that, does that still apply if the boiler is switched to hot water only?
     
  6. newcomers

    newcomers

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    Yes because its still using the same water, all that means is that the boiler wont come on for central heating
     
  7. gas4you

    gas4you

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    its the same primary water/burner that is heated to give you hot tap water via the plate heat exchanger so if you have no system pressure for ch you have no system pressure for DHW ;)
     
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