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Vaillant Boiler pressure issue

Discussion in 'Plumbing and Central Heating' started by GoobaTroopa, 2 Dec 2012.

  1. GoobaTroopa

    GoobaTroopa

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    Location:
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    Hello everyone.

    I'm currently having issues my boiler. We bought our house recently and the boiler in the home was just two years old. It's a Vaillant Combi boiler which services about 13 rads over three floors.

    When we moved in we had no issues with the heating at all. We had a new cooker installed and due to the gas being turned off we had a F fault on the boiler. I didn't noticed this until the next day so I reset the boiler and them I had a low pressure F fault. I opened the cold in valve to re pressurise and put it to just over 1.0 bar.

    This solved it until we had a spell of cold weather and the system was losing pressure daily. I checked for leaks and found none whatsoever. No is colder still, I wake I the morning to find the pressure at 0.0 bar. When I fill it to 1.0 bar, the CH will kick in, in the evening, but the pressure goes to 3.0 bar, which then makes the PRV to kick in and the copper pipe on the outside drips. So much so, that when the CH turns off, the pressure goes to 0.0 bar when we wake up.

    I'm not certain what the issue is and I haven't checked the Air pressure as I not sure if this is the issue.

    Any help would be great as I'd like to save money if its something I can do myself rather than call out an engineer. Which I fear will be inevitable.
     
  2. Burnerman

    Burnerman

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    The first thing to do is to have your expansion vessel repressurised - I think the FAQ's cover this.
    Unfortunately, PRV's have an unfortunate habit of leaking slightly once they have been opened - and a replacement is usually the way to go.
    John :)
     
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  4. MANDATE

    MANDATE

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    I agree you have a expansion vessel problem.
    Most likely lost some of its air charge and the volume of air remaining to compress is too small and makes the pressure higher than designed.
    Could be the diaphragm is 'holed' so water gets to the air side.
    Could be the connecting pipe is partially blocked so vessel can't do what its supposed to.
    Also agree one problem creates another regarding the PRV
     
  5. Bunnyman

    Bunnyman

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    Just look for a local, Vaillant specialist in Northampton on google
     
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  6. DIYnot Local

    DIYnot Local

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