Draining Heating System - Vaillant Ecotec

Discussion in 'Plumbers' Talk' started by LukeSki11, Aug 31, 2021.

  1. LukeSki11

    LukeSki11 Member

    Hi all,

    I’ve removed a couple of rads but i’m now looking to install new rads and TRV’s which would mean isolating/draining the system.

    Even though I had removed the rads, when i open the valve upstairs water still gushes out (i expected it not too given i’d removed a couple but obviously not!)

    So question is with my boiler/tank system how do I go about isolating and draining? And then in reverse refilling as i’m not seeing a filling loop , then again I’m probably being blind!

    Help appreciated!

  2. LukeSki11

    LukeSki11 Member


    Attached Files:

  3. terrymac

    terrymac Screwfix Select

    Have a look in your loft ,you should find two tanks. The small one feeds your boiler / central heating, called an f&e tank ( feed & expansion). The cold feed to that needs to be isolated to enable drain down.
    The larger tank feeds your hot water cylinder.
  4. LukeSki11

    LukeSki11 Member

    Thanks, is it likely the gate valve at the back of the cylinder is the one feeding up to the Tank?
  5. terrymac

    terrymac Screwfix Select

    No it's not likely. Gate valves are notorious for failing ,either not closing fully ,or dont open after closing. I would advise you not to touch any of them !!
    The cold water is mains fed to the loft tanks ,and there could be isolation valves near the tanks. Failing that you could tie up the tanks ball cock
  6. LukeSki11

    LukeSki11 Member

    Excellent, Ta!

    so given its mains fed is my heating system being constantly ’filled’ as such?

    so isolate water, drain from lowest point and then continue to fit?

    Sorry for the questions
  7. terrymac

    terrymac Screwfix Select

    Yes,sort of. Once the system is filled the ballcock closes and the water in the tank keeps the system full.
    Before draining down,inspect the f&e tank for cleanliness. If need be ,clean it before draining down ,to prevent crud from getting into the system.
    When draining from lowest point,vent all upstairs rads ( using the radiators bleed valve )this allows air into system to aid draining.
    You should ,of course,electrically isolate the boiler / central heating controls.
    When work is done and ready to fill up add inhibitor.

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