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Discuss Been recommended to have 'closed system' for Megaflow set-up in the Central Heating Forum area at

  1. Showerman41

    Showerman41 New Member

    Further to my earlier post, the stat trouble returned and we had a plumber visit. Not our usual one, who was too busy, but another independent recommended by him (Gas Safe Register confirmed). He agreed it was the stat and has arranged for an electrician to fit a new one.

    While here, he had a look at the system in airing cupboard (we'd cleared everything out) and said ours was an 'open' one and that a closed one should give more efficiency and get the radiators warmed up more quickly. He gave us a verbal estimate (we do appreciate the difference from a quote :) ), adding that he'd done a few houses on our 20-year-old development and it was about half a day's work.

    Our question is - considering the cost and disruption involved, is the improvement likely to be more than marginal?
  2. Chuck

    Chuck Active Member

    You may not notice much difference short term compared with a straightforward flush but the system should work better for longer due to reduced corrosion/sludge build up. Also, if there ever is a leak there will be no significant damage, typically not the case with an open system, and you'll get a clear indication. (The boiler pressure will drop and it won't fire.) For half-a-day's labour plus parts I'd get it done, but it won't be the most exciting monkey you've ever spent.
  3. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    Problem is I would get your system pressure tested first to see if you have any leaks
  4. Showerman41

    Showerman41 New Member

    Thanks both.

    The system was flushed in November 2014 when the new boiler (Baxi EcoBlue 16) was installed, so that should not be too bad. We saw how much gunge came out and the rads were a lot better afterwards. Our water supplier's hardness figures show "Calcium Carbonate 278mg/l; Calcium 111.2mg/l".

    While those numbers don't mean a great deal to me, our kettle doesn't fur up anything like it did at our last house, so the plumber gets a decent mug of tea... As long as we remember to fill the kettle before he cuts off the water. From experience, they are very good at warning us... :D
    • Funny Funny x 1
  5. Chuck

    Chuck Active Member

    It's not the hardness of the water that matters. The system water in vented systems contains air dissolved (at the free surface in the expansion tank) and this is a major contributor to corrosion of the radiators and boiler.
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