Boiler that was losing pressure self healed ????

Discussion in 'Plumbers' Talk' started by Pimms16, Jan 17, 2020.

  1. Pimms16

    Pimms16 New Member

    Hi all.
    Have found this forum immensely useful to learn about the issue of boilers losing pressure. So thank you for all your knowledge so far.
    I’ll give you the back story,
    Four year old Vailant Ecotec with a magnaclean filter, serviced annually. All was good until the spring. Was having to top up occasionally as opposed to almost never. Frequency was increasing, then we turned the heating off for the summer and i forgot about it. Fast forward to October and I remembered!! Weekly top ups quickly became daily. Called regular plumber who said PRV and expansion vessel were fine (his diagnosis took 15mins). Said must be a leak under suspended floors as we were losing a litre a day and would clearly notice that if it were upstairs.
    (I struggle with the litre part as when I top up from say .8 to 1.5 it takes all of 3 seconds with the taps open. Surely a litre wouldn’t pass through that quickly?)
    For various reasons we haven’t been able to start ripping up the floors (Karndean and tiles ‍♀️). Last week we did and bought a camera to help the search. So far found nothing (but far from finished as next step is wrecking the engineered wood flooring we discovered under the karndean - heartbreaking!) however this week I haven’t had to top up once. Heating been on as usual but pressure steady at 1.3bar.
    ive learned a bit and understand about PRV’s etc and it seemed fairly obvs we had a leak. But how can that be?! Very confused now and very grateful for any theories or suggestions from you good people.btw there had been no loss through the prv pipe.
    Thanks in advance.
  2. Heat

    Heat Screwfix Select

    A bag around the prv discharge pipe would test for water.
    Also an auto vents on boiler or pipework can weep.
    Rad valves etc worth checking their glands for leaks and motorised valves seals can leak eventually.
    Any compression joint check including mag filter.
    Other than inside the boiler, you might have a leak at a pipe but it is possible a leak can seal itself.
    There are leak sealants for adding to a system, but only as a last resort
  3. Pimms16

    Pimms16 New Member

    Hi. Thanks for your response.
    I tried the bag round the pipe and collected nothing.
    Husband had tightened all the rad valves and isolated the one rad that did have a slight leak (weeks before the pressure issue stopped so not the cause).
    Am I right in thinking a leak on auto vent or boiler pipe work would result in water leaking out the boiler? If so there’s nothing. The boiler is in a cupboard so hard to see much beyond the control panel flap but there’s been nothing collect in bottom of cupboard. Nothing around mag filter.
    I was being tongue in cheek suggesting the leak had healed itself! Had no idea this was possible . Is it likely to be a temporary solution? I know you don’t have a crystal ball, just wondered what the balance of probability is before we fork out repairing the damaged flooring?
    Thanks again.

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