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Finding a leak on a combi

Discussion in 'Plumbing and Central Heating' started by trevorbayliss, 21 Mar 2020.

  1. Harry Bloomfield

    Harry Bloomfield

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    Exactly as you would for the valve on a car tyre - Remove the valve cap, lick the end of your finger and wipe it over the end of the valve to check for any bubbles. A more certain way to check, to check the actual valve and around the valve, is to spray around the entire valve area with a water / washing up liquid mix. Again, you are looking for any sign of bubbles.
     
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  3. trevorbayliss

    trevorbayliss

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    Ok thanks. I have some gas detection spray so will try that.
     
  4. dr dolittle

    dr dolittle

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    Combi boiler compression joints will leak...it's what they do. Weeping radiator joints/bleed screws etc have a massive impact on pressure
    Read about hydraulics and understand pressure vs flow, you will discover that tiny weeps will impact pressure in a way that you may find contrary to expectation
     
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  5. DP

    DP

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    Cleaner has done its job The magnetite acts as a sealing agent aside causing others issues. You have a clean system including the weakness that is now devoid of the sealing properties of magnetite leading to system pressure loss.

    I assume you thoroughly flushed out the cleanser (6/7 fill and drains is not unusual)
     
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  6. trevorbayliss

    trevorbayliss

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    DP

    no I didn’t flush many times. Just once I think and I didn’t flush the ufh loop as I didn’t know how to drain it.

    so really I need to flush my system again a few times. But I do think this is the cause of my issues.

    getting all these replies brings me back to Trying the leak sealer when I fit the new magnaclean 2.

    thanks all for helping, every comment helps out.
     
  7. Chris_W

    Chris_W

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    I mentioned in post #13, try taking the pressure to approx 2.8 bar. Did you do this?

    In doing this you can sometimes expose a leak, that isn’t always visible.
     
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  9. picasso

    picasso

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    To be honest I think this is poor advice, your more likely to cause leaks than find them, don't forget the ops system is more than 30 years old.
     
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  10. John D v2.0

    John D v2.0

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    That's because that's the charge pressure of your expansion vessel so there is no more water in it to maintain the pressure in the rest of the system.
     
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  11. dilalio

    dilalio

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    @trevorbayliss do you have any pipework that runs under a suspended ground floor?

    If so, it can leak there and you'll never see it unless you pull up a few floor boards.
     
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  12. trevorbayliss

    trevorbayliss

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    I do in my extension (2 rads) but I can isolate this off and have done so.

    the rest of the house is solid floor so pipes are visible in many places.

    a lot of the pipe work I can expose due to wood floors and I can’t see any signs of leaks here.
     
  13. trevorbayliss

    trevorbayliss

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    Update:

    I think i have found my leak. Just done a drain down in order to clean out my secondary heat exchanger and change over to a new filter.

    Well my drain off valve is still leaking after doing a fill up. This is quite noticeable. So i need a new washer. However, i think this is where i had my leak, but it never showed up on the floor area as it just evaporated away.

    So fingers crossed this has been my issue. Will find out in a few weeks time if so.
     
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