Filling loop sticking

Discussion in 'Plumbers' Talk' started by Whitling2k, Apr 15, 2019.

  1. Whitling2k

    Whitling2k Member


    Quick question for some advice really..

    My boiler (CDI35i mk2) is knackered, expansion vessel broken, blockage in secondary heat exchange, pump worn, auto-bleed valve stuck, etc etc. 15 year old, never serviced, dodgy install by previous occupants mate syndrome!

    So, it loses pressure rapidly - mostly dumped out the back through the pressure release from water boiling in the heat exchanger, or the lack of expansion capacity from the expansion vessel meaning the increased pressure from the hot water has nowhere to go.

    I'm getting a new one in the summer - so just need this one to get me by for a few months.

    Obviously, it behaves much better when it has pressure - but it's spitting out a 2 bar pressure rise in a matter of days.

    Up to now, I've been topping it up almost weekly - just until I can get the new boiler - but recently the valve (small, horrible flexible plastic thing) has started sticking open.

    Any tips on how to manage that? There is no cold-water isolator for the boiler, so unless I'm mistaken, once it snaps and refuses to budge, that's it. Mains water off, drain system fudge however I can, or have mains pressure water pouring out my expansion vessel and pressure relief overflow.

    Does anyone have any knowledge of those boilers have any other options for when (not if) it gets stuck open?

  2. ESPlumb

    ESPlumb Member

    You could replace the filling loop or fit an isolator on the cold pipe to stop the continuous flow of water.
    There’s no real solution to the problem that doesn’t involve paying for parts and labor, and it wouldn’t be economical if the boiler is to be replaced soon. You might as well put this money towards the new boiler.
    If the boiler is as bad as it sounds it might be worth turning it off and isolating. You do not know what other problems this “dodgy install” has, so best not risk your health.
    Whitling2k likes this.
  3. The Teach

    The Teach Well-Known Member

    if its the plastic integral filling link,then it is fairly easily exchanged although fiddly ;)

    With correct servicing there actually a decent boiler,shame it has been neglected :mad:
    Whitling2k likes this.
  4. Whitling2k

    Whitling2k Member

    Yeah, it's a bit of a bummer really, we were impressed with the boiler when we first saw it - but unfortunately the house was DIY extended and half-assed-renovated by two past owners... a builder then a joiner - all I can say is that I hope they took more care over their customers work!!

    I had thought about putting an isolating valve on the cold-water in-feed - but it looks like the filling loop is tapped straight off the main cold-water inflow to the boiler - within the boiler - so it would have the side effect of cutting our hot water too.

    Worcester-Bosch's fixed fee call out engineer and a local lad have both said it's safe - just uneconomical to fix.

    I think I'll try live with 0-bar pressure it will also cost less in inhibitor costs - less water I put into the heating loop, the less inhibitor-ladened-water there is to come out!

    Thanks for confirming :)

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