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Draining microbore system

Discussion in 'Plumbing and Central Heating' started by goalc, 21 Mar 2006.

  1. goalc

    goalc

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    Hi
    I am looking to drain my microbore heating system as I want to put TRV's on the rads (there are none on at all and some of the current valves are broken anyway). On my old system at my previous house there was a small "tap" downstairs that I connected a hose to to drain the system, but I cannot find one here at all.
    However, every radiator downstairs has what looks like a small drain plug on it (in-between the main part of the rad and the valve - a small t-junction with a screw on cap on it on the underneath side), so my questions that I hope someone can help with are :

    1) can i drain the whole system through one of these
    2) if not, do I need to drain it through all of them
    3) if this only drains these rads, how else can i drain the system ?

    Any advice is appreciated

    (I presume that to fit TRV's on all the rads (except one) I do actually need to drain the system ?)
     
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  3. noonespecial

    noonespecial

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    Water will find it's own level in your system, therefore you have to drain down to a level below the lowest TRV.

    Is there a drain off valve by the boiler? That may be a good starting point to drain down depending on the pipework arrangement.
     
  4. goalc

    goalc

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    so, if the "drain tap" (whatever it is on the rads) is below the TRV's I should be Ok to drain through here and then fit the trv's ? I dont mind if the carpets get a bit mucky as we will be replacing them all anyway.

    there is no valve near the boiler and i cant find anything similar anywhere else !
     
  5. brumylad

    brumylad

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    whats the ground floor made of. suspended wooden boards type or solid concrete type. :?:

    Are the ground floor rads each supplied by a pair of pipes decending from upstairs as opposed to pipes coming up through the ground flloor. :?:
     
  6. Al-Glasgow

    Al-Glasgow

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    draining on the lowest point will remove most of the water from the heating side.

    If you have an open vented system, you could block the open vent and blow air thru a radiator tail, and collect from the other tail. Hopefully you would drain ALL water this way.

    If its a COMBI then ask a pro lol

    Al
     
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  8. goalc

    goalc

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    The ground floors are made of concrete. The rads are supplied by a pipe which comes out of the wall horizontally and then goes 90 degrees upwards to the valves.
     
  9. goalc

    goalc

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    sorry for the dumb question - how do i know if it is an open vented system ?

    i do know that the boiler is not a combi :D
     
  10. brumylad

    brumylad

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    open vented = expansion tank in the loft or high cupboard

    unvented = pressure guage on the boiler or on the heating pipework reading (hopefully) between 1 - 2 bar.

    Sounds like your rads are all supplied by pipe drops from the first floor hence the drain valve on each rad. Opening anyone of these valves will drain most of the system and the pipes to that particular rad. For each subsequent rad on the ground floor, the pipe drop will contain water which will only be released by opening the drain on that rad.

    adding thermo valves may require some alteration to the copper pipe tails. (soldering etc)
     
  11. Expertboy

    Expertboy

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    Oh and then the fun begins when you fill up, with air locks :evil:
     
  12. DIYnot Local

    DIYnot Local

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