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Discuss Do I need to refill loft tank after draining some rads? in the Plumbing Forum area at

  1. ElCornDoggio

    ElCornDoggio New Member


    I'm a total novice at diy, having just bought my first house. Sorry for the dumb question that follows.

    I've drained and removed a couple of large rads for decorating, but now they're back on, I'm unsure if I need to refill the loft tank somehow to make up for the water lost?

    It's a very old conventional boiler, with tank in the loft so gravity fed. Will the system just refill itself to it's previous level, or is there something I need to to do to make it happen?

    Thanks in advance!
  2. townfanjon

    townfanjon Trusted Plumber GSR Top Contributor!!

    Assuming the ball valve is working yes it should fill itself , tank should only be a third full when cold , not full
    • Agree Agree x 3
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  3. king of pipes

    king of pipes Trusted Plumber GSR

    How did you drain the rads ? if you only shut the valves off and draineď the water into a container from the rads and then removed its just a matter of doing the same in reverse and refilling and venting the system . Cheers kop
    • Like Like x 1
  4. ElCornDoggio

    ElCornDoggio New Member

    Thanks guys. Yeah I just closed the valves, so it seems I'm good and don't have to venture into the loft after all.

    Cheers :)
    • Agree Agree x 1
  5. DAVE01

    DAVE01 Member

    Best way to fill heating weather be open vented or closed is to back fill it through return on down stairs rads only thing you have to watch is small tank in attic make sure that overflow of tank is connected and ballcock tied up fill it off mains weather it be open or a closed system this will take care of any air in system on a open system it could break you heart trying to get a few rads back working because you filling from the top down on a open system
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