When Tado TRV calls for heat, all dumb rads turn on above thermost heat?

Hi all, my situation, please can anyone help?

One house Tado thermostat in hall, 2 new Tado TRVs (upstairs bedroom and dining room), rest of the house dumb TRVs. We also have a wood burner in the dining room. Wood burner on and the house gets hot 25 deg. We have a Tado set to warm our bedroom at 18 deg, all other rads are now hot even when the stats are set to 18 but the rooms are over 25?

Surely the rads with dumb stats shouldn't get hot when the room is at higher temp? Is there a fault or a simple solution without buying 8 more Tado TRVs?

Best Answers

  • hugbilly
    hugbilly ✭✭
    Answer ✓
    No they shouldn’t, perhaps there’s a problem with the old TRVs . . .
  • Rob2
    Rob2 ✭✭✭
    Answer ✓

    No that is not possible. When you want to heat a single room and not the others you need to fit smart TRVs everywhere.


  • cbd20
    cbd20 | Moderator
    Hi @Tuffois. Tado will turn the heating on according to its schedule. All non-tado equipped radiators will therefore get hot if their manual "dumb" trv allows water through.

    You say the house is at 25 degrees - is that confirmed in all rooms?

    Also, I'm assuming your dumb TRVs are the classic numbered 1 - 5. What number do you have them set to? The scale is typically relative and doesn't necessarily equate to a precise temperature. Position "5" is typically fully open though, so the valve essentially won't shut. This means regardless of room temperature hot water will flow through...

    Have you confirmed that if you turn the dumb TRVs down, that they don't heat up?
  • I installed Tado just last week, replacing a dumb system which included several TRVs which were first installed 33 years ago. Based on former operation of the system, and subsequent informal tests with hot water in the washing up bowl and also a hair drier, it appears that not one of the old TRVs was working as a thermostat and they effectively worked as manual on/off switches only by twisting them. So I would definitely consider that your old TRVs could be junk - at least if they are as old as mine.

    In contrast my new Tado system seems to be working very much as hoped, with temperatures adjusting as they should and my condensing combi boiler swapped from relay mode to eBus and running far cooler and more efficiently than it has for the past decade.

  • Hi all thanks for the replies. The dumb stats are 17 years old but all work. They are all set between 2-3 on the 1-5 scale. My problem is if I only want to heat one one room with a smart TRV it is connected to my main zone wired controller in the hall which then heats all of the dumb trvs. They are still getting hot and demanding boiler heat when that room temp goes above the stat temp set. Is there a way to control a single room with smart trvs without this happening?
  • Ok. Thanks.. I understand that I can't do one room. Current situation bedroom has just demanded boiler correctly. Dining room has log fire on and hot. The radiator with smart thermostat at 18 and it's pumping out heat with the thermostat measuring 29! That cannot be right?
  • @Tuffois Check that the thermostat valve pin, below the Tado SRT, is actually free to move and able to close. You'll need to remove the SRT and then press down on the pin to make sure it can move. It'll be stiff/sprung so you'll probably need something to press it down with. Flesh alone might not be up to it. Set the target temperature for the SRT to 25 to open the head and release pressure on the pin before you try to remove it.

    If it's stiff or stuck then you'll need to push (or maybe light tap it) until it moves. Then work it a few times to loosen it. Once you've done that you should probably recalibrate the Tado.

    If that doesn't fix it there might be an internal fault within the valve, causing leaking. Other than that I have no ideas unless the Tado SRT is actually faulty and not pressing down on the pin.

    Disclaimer : I'm not a heating engineer, just a bloke with Tado and YouTube.

  • Thanks mate, appreciate the comprehensive answer.
  • Dumb stats really are "dumb".

    They work by having a ball of wax that melts and expands inside what is basically a tiny bicycle pump and that pushes the piston out to push the pin and close the valve. When the wax contracts, a spring pushed the piston back and the valve opens again.

    The melting of the wax and expansion/contraction of the wax liquid isn't a rapid, not is it an accurately calibrated process.