TRV reading but not actuating fully

I have a separate lounge and dining room with an open doorway between. Both are on identical schedules but the lounge is controlled by a temperature sensor and the dining room by its trv.

The dining room trv appears to have virtually stopped actuating the valve and is letting the lounge to heat it up.

Occasionally the trv actuates for a brief moment then switches off. I have turned it up manually and it worked fully when I did this but reverted to not doing when back on schedule.

See photos:


  • Any suggestions, anybody?

  • The lounge radiator appears to be doing a good job of heating the dining room. The temperature measured by the dining room TRV is always about 0.3°C hotter than the temperature measured in the lounge. I suspect the TRV in the dining room is not activating because it senses the temperature in the room is already climbing. It doesn't know why, in theory it could be solar gain or a solid fuel fire in the room. You could try moving the temperature sensor over to the dining room, but it's always going to be difficult to run independent schedules for rooms that are open to each other.

  • Montage
    Montage ✭✭✭

    I would suggest it’s a good example of when not to zone.

  • I would suggest a negative temperature offset to the diningroom smart radiator thermostat….as it seem to sense a higher temperature than the (remote) sensor in the lounge.

    As I understand you use a remote temp sensor in the lounge, which is not influenced by the radiation from the radiator to same degree as the smart radiator sensors close to the radiator….

    Please let us hear how this would change the performance,…..

    You may have to tweak the offset, but try to start with - 1 deg C.


  • I did exactly that the other day and while there is a pick up inactuations later in the day it does nothing to explain why the dining room trv does not actuate at the start of the day when it won't yet be affected by the lounge.

  • Hi again,

    try a little more offset….I suggest…..

    I have two radiator thermostats, as you in physically connected rooms, on two different size radiators, and the two valves are not equal in response, but I have them operating ok now, with a slightly higher load on the larger radiator due to a lager offset, but same setpoint/wanted temperature for the two… you can tweak it to work!

    good luck