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Discuss TRV fitting to room rads in the Central Heating Forum area at

  1. Bogart

    Bogart Member

    Probably been assked before but cannot see where so here goes again. I have a few rooms with twin radiators and am wondering is it prudent to bit both with a trv or just the one of them. Distances between rads obviously depend on room sizes but range from say 5m to 10m.

  2. Chuck

    Chuck Active Member

    To comply with current building regulations (Part L) you need all of them fitted with TRVs unless the thermostat that controls the zone is in the same room, in which case a TRV must not be fitted to at least one radiator that that influences the zone thermostat.
  3. steadyon

    steadyon Active Member

    Assuming the radiators are on a two pipe circuit, you should fit a TRV to each. A TRV senses the temperature of the room, and when this reaches the pre-set required temperature on the TRV dial, the valve is fully closed. If you had another radiator in the same room without a TRV, this second radiator would never shut off until the room thermostat turned the whole central heating system off.
  4. Best

    Best Trusted Plumber

    Distance between radiators is irrelevant.
    As said in above replies, all rads need thermostatic control, except if where there is a room stat.
    If you have a room with 2 rads and only one has a TRV, the other rad will keep heating and usually overheat the room, unless perhaps in very cold weather.
    On a similar point, - that is why you strictly speaking should close room doors to prevent one room set at a higher temperature, heating the next room that has a TRV turned lower
  5. Ric2013

    Ric2013 Plumber

    If they are on a separate drop per room, could you put the TRV on the pipe serving both rads? Then you'd have only one control for each room with manual valves left as is.
    Giving you full thermostatic control and saving the energy used in bending to each radiator and manufacturing twice as many new valves...
    • Funny Funny x 1
  6. Ric2013

    Ric2013 Plumber

    Well, a TRV on a drop may look strange, but from a functional point of view should work very well. Actually saw that on a house I used to rent. Landlord was a heat pump engineer.
    • Like Like x 1
  7. Best

    Best Trusted Plumber

    Really a good idea actually! Won't make any saving on the pipe runs though as heated water just stops flowing when on normal rads that both have TRVs.
    The pipe drop would have to be a reasonable distance from the rad or the heat from the rad would make the TRV shut off too early, but I guess the TRV could be installed as low as possible.
    I still would prefer the option of closing one rad off
  8. Bogart

    Bogart Member

    Both are on seperate drops.
    • Dislike Dislike x 1
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