Ch system over pumping and other issues

Discussion in 'Plumbers' Talk' started by Chrisathome, May 13, 2018.

  1. Chrisathome

    Chrisathome New Member

    Hi all, I boughta house with an old vented ch system. This has a Baxi back boiler, I have had it serviced and it is ok. However the system is constantly over pumping back to f and e tank when running. I have flushed the rads and the system heats great. Pump is set to minimum, but still over pumps.

    Other issues...

    F and e tank over flows a little drip when system runs

    Though I replaced the Honeywell 2 port that is suppose to shut off the radiator circuit, and it closes when it is suppose to, the system still puts heat to the rads even when set to hot water only.

    There is still corrosion going on, every time I drain the system it is very brown

    Any suggestions?

    See images of my pipe work. And my guess for the plumbing circuit

    Attached Files:

  2. Crowsfoot

    Crowsfoot Well-Known Member

    It's that CH cold feed Chris that's the problem here (were it tees in) the pumps effecting it.

    You could tee it (the cold feed) directly into the 22mm expansion pipe above the air separator with a 22mmx15mmx22mm tee and then cap the cold feed off with a 15mm stop end.
    It's not seen as good practice, but methinks it should solve your pump over problem.

    Mixing with the air like that will create a tremendous amount of the dreaded system sludge (I would bet a bit of it is stuck on that new MV preventing it from fully closing).

    There are other options, however, the above is the easiest cure.
  3. Mike83

    Mike83 Well-Known Member

    A spartan vessel will do the job.
    Will eliminate pumping over as there would be no header tank.
    Simple to fit and comes with an auto air vent.
    A spartan is a combined feed and expansion.
  4. Chrisathome

    Chrisathome New Member

    Hi crowsfoot, thanks for reply. Do you mean bring in f and e expansion tank feed onto the hot line coming into the seperator ?

    Why would this help?

    Thanks, chris
  5. Crowsfoot

    Crowsfoot Well-Known Member

    It will bring the cold feed into what should be a "neutral zone" making it a combined feed and expansion for the heating system.

    At the moment when the pump is on it is dragging water from the cold feed into the system continually and then depositing the excess water over the expansion pipe into the header tank.

    This cold feed and expansion practice was done extensively in the early 70s but is now frowned upon.
    Converting it to a pressurised system is another more modern thinking option.

    However, everything considered, I reckon the "combined feed and expansion idea" is your best first option for the fix.
    Last edited: May 14, 2018
  6. Peterdevon

    Peterdevon Active Member

    Or put the feed before the air separator
  7. Chrisathome

    Chrisathome New Member


    Thanks crows foot,

    Aha so I think you mean connect the feed from the f and e to the ‘vent’ from the separator? This is a relatively simple change I could implement ASAP
  8. Crowsfoot

    Crowsfoot Well-Known Member

    Let us know how you get on with it.

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