Automatic Air Release Valves Leaking

Discussion in 'Plumbers' Talk' started by YUpNorth, Nov 18, 2021.

  1. YUpNorth

    YUpNorth New Member

    Hi all, (bullet points are the quick questions - further down are the longer questions)

    I have a Baukmann Automatic Air Release valve in my loft that are leaking despite me having first cleaned them up and then secondly replaced them.

    • Why would new valves leak water?
    • Could they be drawing air into the system?
    • What are the downsides of closing them fully?

    Longer story with questions I recently moved into an old house with an old wet underfloor heating system. The heating network is in two sections, upstairs and downstairs both with their own pump and each room of the house with its own thermostat and related inlet valve.

    Downstairs never has an issue... turn the room thermostat up, a valve opens and a pump kicks in... everything gets warm.

    Upstairs seems to develop issues of the pump running dry, I assume thats what's happening as its noisier than normal running and also the pump is hot/warm but the feed water pumps into the rooms are cold.

    In the loft there are a number of air release valves, each on an individual feed/return pipe. When we moved in there were (and still are) buckets underneath to capture any leaking water so its not a new issue.

    When the pump runs dry I top the system up, the air valve always spit some air out. It runs for a bit (24 hours in general sometimes more) and then back to the start of the cycle.

    I'm wondering... when I'm topping the water up... its then getting hot and in theory expanding... then it gets cold of a night when the heating is off and contracts... could the valves be allowing air in at this point?

    Also the leaking valves, when I moved in I took the innards out and cleaned them up as they were covered in a thick green moosey slime. That kind of worked maybe but also it was summer so the heating wasnt on much... I've also completely replaced the valves like for like... but alas this morning there was more water escaping - is there something else I need to do to sort the valves? Also is there an alternative? As the first sign (other than a daily loft inspection) is a wet patch in the ceiling.

    Any help or advice would be hugely appreciated :)

    Attached Files:

  2. kiaora

    kiaora Guest

  3. pppmacca43

    pppmacca43 Super Member

    I’ve not come across that particular brand but it would be off for new ones to leak. They may weep slightly from the top as they shut off maybe though. I don’t use any other brand of aav anymore in domestic settings other than flamco if I can help it, had too many problems with cheaper ones failing or leaking. Maybe try one flamco and see if it stops the leaking issue, it it works try change them all.
    The u shouldn’t keep getting air out of them so that does point to air being drawn in. It is possible the AAVs are where this is happening, or u could have a minute leak somewhere pulling air in. Also when u are topping up and adding fresh water each time u have finished the inhibitor so this will need topping up too at some point, as this will in time not help with the valves leaking and the creation of gasses(air)

    Attached Files:

  4. YUpNorth

    YUpNorth New Member

    Thank you, I'll definitely look into the Flamco ones!

    I totally hadn't considered (or heard of) adding an inhibitor. Is there a brand you recommend so I can do some research/Googling :)
  5. pppmacca43

    pppmacca43 Super Member

    Any is fine, screwfix do a few different ones, they all do the same thing. Obviously you need to get your issues sorted first and add it when you are happy you aren’t going to keep needing to top up all the time.
  6. Jimbo

    Jimbo Screwfix Select

    There should be an expansion vessel somewhere, the 'dry' pressure needs to be checked (i.e. when the system is in need of water, check the air pressure in it and if under 1 bar pump it up to that, then refill the system to 1.2 bar. There should also be a pressure relief valve somewhere, put something under that and see if water is being discharged there.
  7. exbg

    exbg Active Member

    I could not be bothered to do more than skim read most of the responses, but apologise if. missed anything of value.

    Answers to questions:

    1. Where are they leaking, precisely?

    2. yes, they can, if on the negative side.
    Run system. Remove cap. Use soap solution (or spit) to smear on valve. If the fluid sucked in, they will be drawing air in. Have a 2nd person to turn heating while you are testing. It is possible to only occur on start up

    3. Only negative is they stop being Automatic
  8. heatyman

    heatyman Well-Known Member

    This is always a problem on oil combis when the pump can produce negative pressure if the system pressure is low. I always closed the AAV's after servicing and had very few call backs before the next service. If your system is producing air, it will always colllect at the top, and you will notice any air by the cooling of some rads. It is a short job to release and relock the valves. Braukmann valves were always considered one of the best makes as they are easily serviceable, and were what I would choose over the budget items.

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice