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Discuss TRV - Radiators either Hot or Cold in the Valves & Taps area at UKPlumbersForums.co.uk.

  1. jranger

    jranger New Member

    Hi - I have a bedroom where the radiator is either blazing hot or cold. It is fitted with a TRV (I have tried several different ones to eliminate the TRV as the issue). When the TRV is set to "0" the radiator remains cold. At all other settings the radiator gets hot and stays hot even when the room temperature is 25 degrees +. I would expect that the TRV would at some stage close off the valve and the radiator would cool down especially at a low setting. If the valve is turned to "0" it does go off. As I said, this happens with different TRVs, some that are working normally that I have swapped from other radiators. So the radiator works, the valve works, the TRV works but the room temperature is never regulated by the combination. Is this a balancing issue?
  2. PlumbBobBob

    PlumbBobBob Guest

    when the trv is at "0" it is turned off so will not heat up at all. all the other settings will to a certain extent allow the radiator to heat up, 5 being fully open and each subsequent lower number closes the trv by a small amount while still being open.
  3. steadyon

    steadyon Active Member

    TRV's sense the room temperature, but they sense it close to the valve itself. It is quite possible, for example, to have a TRV exposed to a cold draught, while the rest of the room is at the set temperature, and the TRV will not turn off.
  4. jranger

    jranger New Member

    Thanks - That's what I thought. So is it that even at a setting of "0.5" there is enough flow through the radiator to maintain heat and during operation a TRV NEVER moves to a completely OFF state? In that case why do my other radiators not behave in this way? Is it possible that my lockshield valve is fully open and needs to be closed down a little?
  5. jranger

    jranger New Member

    Thanks - The valve is not in an exposed location, I have tested it with an electronic TRV (Energenie) which showed that the room temperature was 25 degrees as measured by the TRV. I had set a target temperature of 18 degrees, the software app with the e-TRV was telling me that it was cooling towards the target temperature yet the radiator remained hot until the heating timer on the boiler turned off. This is the same behaviour I see with a standard TRV.
  6. Best

    Best Trusted Plumber

    Sounds like your TRV is faulty.
    When you turn it to 0, the rad is off, you say, so the head part must not be pushing the pin far enough down for some reason. Some valves I see doing same - the odd one of Peglers Terrier TRVs for example.
    If you have identical TRV elsewhere, swap the head part to test. If rad still keeps heating, get a plumber to replace entire valve