Boiler (Vaillant) losing pressure every couple of months?

Discussion in 'Plumbers' Talk' started by Bill1989, Mar 21, 2020.

  1. Bill1989

    Bill1989 New Member

    Hi all,

    Bit of a strange one here. I have a new Vaillant Ecotec 830 installed last August. Around the end of November the pressure suddenly dropped to 0.1 bar overnight - called a plumber in to look for a leak, didn't find one, repressurised. It happened again the next day. Then the strange part - it has happened regularly every couple of months, there or thereabouts - 2 losses of pressure in 2 days at the end of December, and now again yesterday and today.

    I had the Vaillant technician out in December who said the boiler is fine and it must be a leak. However, one plumber I asked round said this is a normal thing to happen to Vaillants and it is something to do with regulating the system.

    Is this true? If so, why wouldn't the Vaillant technician have said about it? Should also add the original fitter came back and thinks it is a leak. I have checked every inch of my pipework (only a 2 up 2 down so didn't take long) and nothing is leaking.

    Can anyone shed any light? It's frustrating and confusing me, and with a 9 week old baby in the house the last thing I want is unexpected boiler failure in the middle of the night

    Thanks in advance
     
  2. terrymac

    terrymac Screwfix Select

    Have a look at the pressure relief pipework ( copper pipe on outside wall) to see if any sign of water leaking from it. Maybe tie a balloon over it.
    You are either loosing water from the boiler itself ,or on internal pipework/ radiators.
     
  3. Bill1989

    Bill1989 New Member

    Nope - did that the first time, nothing came out. I am positive there isn't a leak, and surly if there was the pressure drop would be gradual rather than sudden? It goes from 1.5 bar to 0.1 within a couple of hours.
     
  4. terrymac

    terrymac Screwfix Select

    For pressure to drop in a sealed system,water has to be escaping somewhere.
     
  5. Bill1989

    Bill1989 New Member

    I know, which is why it's so irritating. Have you ever heard of a boiler regulating pressure on a scheduled basis?
     
  6. terrymac

    terrymac Screwfix Select

    As far as I am aware there is no such thing as a boiler " regulating pressure" of the water in the sealed system that it's connected to . What exactly could that possibly entail , releasing pressure of its own accord ,so to speak. If so ,where would it expel the water ,it can't make it disappear into thin air.
     
  7. Mike83

    Mike83 Screwfix Select

    Is does sound like it’s losing pressure but the pressure sensor may be giving false readings that make the loss seem erratic.
    If the pressure regularly drops it’s losing water somewhere.
    Heat exchanger is a possibility.
     
  8. Bill1989

    Bill1989 New Member

    2 engineers have okd the heat exchanger. My main aim of starting this thread was to confirm that boilers can't be programmed to regularly depressurise, which it sounds like they can't. Thanks for the replies
     
  9. quasar9

    quasar9 Screwfix Select

    Plenty of posts out here but in summary , the first test is to see if the pressure loss is in the boiler or elsewhere.
    1. Pressurise boiler to 1.5 bar and then turn off the fill loop valve/tap.
    2. Switch off power to boiler and controls
    3. Isolate all inputs and outputs under the boiler.
    4. After a period of time when you normally expect the pressure to fall, Check pressure.
    5. If pressure gauge is part of the boiler
    And still show full pressure the leak is in system side not boiler.
    Open isolators and confirm by falling pressure

    6. If the pressure gauge is external to the boiler, ie near an external expansion vessel, the opposite will happen.
    A fall in pressure shows external leak. If no fall, the leak is in the boiler confirmed by a drop in pressure when isolators are opened
     
  10. Teki

    Teki Screwfix Select

    This may not be practical given the OP has mentioned the loss of pressure is infrequent and also this:

    Are you sure you have identified the correct pipe from the pressure relief valve?
     
  11. Ken Nathan

    Ken Nathan New Member


    I have a similar problem My boiler is Vaillant ecotec plus 831 5 years old losing pressure from 1.9 bar to 0 bar every 2 Hours. NO leak from PRV and no visible leak inside the boiler. I have checked ALL the piping NO leak. there is no air coming out of any radiators help please
     
  12. Teki

    Teki Screwfix Select

    Did you have the case open to check for no leak inside the boiler? Have a look around all the radiator valves for leaks or green stains on the pipes.
     
  13. Ken Nathan

    Ken Nathan New Member

    Hi,

    Yes I had a look inside the boiler it looks brand New without any leak or rust.
    I checked with boiler inlet and out let to the radiators still the boiler lost pressure from 1.9 bar to 0 bar ,there is NO leak from condensing pipe or PRV pipe outside. the boiler is losing even if it is off. I am filling the boiler three to four times every day for the last week but NO sign of leak at all from radiators or boiler and NO air in the radiators.
     
  14. Teki

    Teki Screwfix Select

    The cover should only be removed by someone who is Gas Safe Registered!

    Anyway, can you locate the Schrader valve on the expansion vessel (usually on the right inside the boiler)? It is the same as you would find on a tyre. Check the current pressure level with a tyre pump/compressor. Don't try to fill it with water in the system.
     
  15. Ken Nathan

    Ken Nathan New Member

    The front cover was removed by gas engineer NOT me ,he checked everything including Expansion tank with tyre pump and said the pressure was correct but he could NOT find where the leak is. All this check was done over three weeks ago. Due to current situation I do not want to call engineer at the moment again.
     
  16. terrymac

    terrymac Screwfix Select

    Did you isolate the boilers flow and return valves ? Did pressure drop rapidly when they were closed ?
     
  17. Ken Nathan

    Ken Nathan New Member

    I closed both valves and made sure the pressure was 1.5 bar, and when the pressure dropped to 0 bar i refill the boiler to 1.5 bar and opened the valves again the pressure did not drop
     
  18. terrymac

    terrymac Screwfix Select

    Ok ,if you are adding water 3 or 4 times a day then water has to be escaping somewhere .post pics of the outside PRV pipe ,and the plastic condensate pipe where it exits the boiler and where it terminates.
     
  19. Ken Nathan

    Ken Nathan New Member


    I put a plastic bags on both the condensing pipe and the copper pipe for PRV valve over night when the pressure was 1.9 bar in the morning I checked the boiler the pressure was 0 bar , but there is NOT a drop of water in either bag. That is why I am worrying where the water I am adding every day going to. Both inlet and out let was closed using the allen Key.
     
  20. terrymac

    terrymac Screwfix Select

    Thats why I asked for pics.
    1. To establish that you are looking at the correct pipes
    2. To try to establish the route of them.
    Only being on site would enable the leak to be found , pics are the next best thing.
    Once had a condensate pipe going thru a cavity wall ,the plastic pipe had split within the cavity and the water lost within.
    Another occasion ,on this forum , a person posting told us there was Nothing coming out the condensate pipe outside. Turned out he was looking at a toilet overflow pipe !!!
     

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