1. Visiting from the US? Why not try DIYnot.US instead? Click here to continue to DIYnot.US.
    Dismiss Notice

Losing pressure...

Discussion in 'Plumbing and Central Heating' started by MICH43L, 27 Sep 2020.

  1. MICH43L

    MICH43L

    Joined:
    12 May 2015
    Messages:
    70
    Thanks Received:
    2
    Location:
    Liverpool
    Country:
    United Kingdom
    Hi all.

    Short version:
    I have a combi boiler which is losing pressure.

    Long version:
    Boiler was losing pressure since around June/July. Put a bucket under the overflow and worked out that we were losing 1/2 pint per day.

    Boiler was serviced and fitted a new pressure relief valve on 11th September, since when I've re-pressurised the system twice.

    We're now losing about 1.25 pints per week down the boiler overflow (plus evaporation), and it's dropping from 1.5 to 0.8 in the same time period. It takes 27 seconds to fill it back up, which would seem like more than we're catching in the overflow bucket, unless the feed is very slow.

    To give an idea of size, There are 14 radiators on the system.

    (Full disclosure: I did replace and re-plumb a radiator back in November, but pressure tested everything and left the floor up for a few days to check it was OK. We've no obvious leaks coming through the ceilings anywhere.)

    Haven't bled the system through in a couple of months. Going to do that later.

    The heating has not been on. Just hot water.

    I'm stumped as to the cause of the pressure loss, any ideas?
     
  2. Sponsored Links
  3. ianmcd

    ianmcd

    Joined:
    15 Aug 2010
    Messages:
    23,486
    Thanks Received:
    9,695
    Location:
    Lanarkshire
    Country:
    United Kingdom
    when you say over flow , do you mean pressure releif valve pipe work ? a combi boiler doesnt have an over flow, post some pics please
     
  4. MICH43L

    MICH43L

    Joined:
    12 May 2015
    Messages:
    70
    Thanks Received:
    2
    Location:
    Liverpool
    Country:
    United Kingdom
    IMG_20200927_173811.jpg

    Thanks. Yes, the one in the centre leading outside.
     
  5. Elkato531

    Elkato531

    Joined:
    22 Jul 2009
    Messages:
    1,091
    Thanks Received:
    277
    Location:
    Sussex
    Country:
    United Kingdom
    The plastic pipe? that is the condense drain and should discharge water. The pressure relief is the one on the far left which goes out through the wall. You shouldn't have any water through this, if you do, your pressure will drop.
     
    • Thanks Thanks x 1
  6. CBW

    CBW

    Joined:
    26 Sep 2019
    Messages:
    9,044
    Thanks Received:
    2,413
    Location:
    North
    Country:
    United Kingdom
    That’s your boiler condensate pipe, so if that’s the reason for the pressure loss, then it’s likely to be a cracked heat exchanger. Your condensate pipe should go to a drain, or soak away and should discharge water when it’s condensing. You may have a leak on your heating system if this isn’t the reason for pressure loss.
     
    • Thanks Thanks x 1
  7. terryplumb

    terryplumb

    Joined:
    8 May 2017
    Messages:
    6,160
    Thanks Received:
    1,276
    Country:
    United Kingdom
    Does your pressure gauge get to around 3 bar when central heating is on ? As advised above ,check the pressure relief pipe outside to see if water is escaping there.
     
    • Thanks Thanks x 1
  8. Sponsored Links
  9. MICH43L

    MICH43L

    Joined:
    12 May 2015
    Messages:
    70
    Thanks Received:
    2
    Location:
    Liverpool
    Country:
    United Kingdom
    Thanks all, very helpful. I will check the other pipe. Heating has not been on yet.
     
    • Like Like x 1
  10. ianmcd

    ianmcd

    Joined:
    15 Aug 2010
    Messages:
    23,486
    Thanks Received:
    9,695
    Location:
    Lanarkshire
    Country:
    United Kingdom
    If the heating hasnt been on and you are getting that much water from the Condensate discharge pipe (not overflow) most likely culprit is the heat exchanger, nothing you can sort your self I am afraid, and if as you say it is going into a bucket it is not installed properly
     
    • Thanks Thanks x 1
    • Like Like x 1
  11. MICH43L

    MICH43L

    Joined:
    12 May 2015
    Messages:
    70
    Thanks Received:
    2
    Location:
    Liverpool
    Country:
    United Kingdom
    The bucket was just a temporary measure to figure out where the water was going (and how much). Not sure what volumes of water to expect from the condensate pipe over the course of a week - any thoughts? Would a damaged heat exchanger not be picked up on a service? Are they expensive to replace?

    Cheers
     
  12. ianmcd

    ianmcd

    Joined:
    15 Aug 2010
    Messages:
    23,486
    Thanks Received:
    9,695
    Location:
    Lanarkshire
    Country:
    United Kingdom
    Nope wouldnt be picked up on a service, unless you state you have pressure loss, if the heating is not being used there should be next to nothing in your bucket, empty the bucket, turn the boiler completely off , no heating no HW and if you are still getting water in your bucket dear Lisa , it is indeed the heat exchanger, might still be under warranty though, if not Ideal fixed price repair is your best bet
     
    • Thanks Thanks x 1
    • Like Like x 1
  13. MICH43L

    MICH43L

    Joined:
    12 May 2015
    Messages:
    70
    Thanks Received:
    2
    Location:
    Liverpool
    Country:
    United Kingdom
    Cheers. Every day is a schoolday :)
     
    • Like Like x 2
  14. DIYnot Local

    DIYnot Local

    Joined:
    3 Sep 2019
    Country:
    United Kingdom

    If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

    Select the supplier or trade you require, enter your location to begin your search.


    Are you a trade or supplier? You can create your listing free at DIYnot Local

     
Loading...

Share This Page