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Water pressure too high for boiler?

Discussion in 'Plumbing and Central Heating' started by chuckalicious, 28 Nov 2016.

  1. chuckalicious

    chuckalicious

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    Location:
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    I have an older Feroli Modena 102 combi which came with the house.

    Never had any pressure issues until the system was partially drained for an extra radiator to be added. After topping water back up to approx 1.5 bar it would drop to 1 bar over a couple of days. No leaks found. When heating, pressure goes to about 1.7-2 bar.

    Plumber suggested it needed re pressurised and did so and it seemed to hold the pressure better. However a week later it had to be partly drained again due to an issue with the rad. After refilling it again started dropping pressure.

    I was googling repressurising the expansion tank and came across a thread on another forum where someone said their boiler had a hot water part within the pressure tank in the combi and his water pressure was too high for it and it kept losing pressure.

    Interestingly over the summer I found a pressure reducer on my water main and opened it up as my garden hose wasn't great. This helped the hose.

    Does anyone know if high water pressure could cause such a problem with the boiler?

    Thanks.
     
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  3. flameport

    flameport

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    If the pressure drops, then water is leaking out somewhere.

    Completely normal, and is due to the water expanding when heated.

    There is a pressure vessel inside the boiler full of air, which provides a space for the heated water to expand into. If that is defective then the pressure will increase very quickly when heated and once over 3 bar or so, water will be expelled via the relief valve, resulting in there being little or no pressure at all when the system cools.

    Incoming water pressure to the house is unrelated and will have no effect on the boiler.
     
  4. chuckalicious

    chuckalicious

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    Ok thanks, clearly a misinformed post on the other thread then. The pressure never goes above 2 bar.

    Thankfully just earlier today I did find a leak in a joint which has now been fixed and the pressure is holding. Thankfully.
     
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