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Solution for smart thermostat radiator valve (TRV) inaccurate temperature measurement.

Hi, I like many other people have struggled with the completely inaccurate temperature measurement of the smart TRVs, this causes the radiators to shut off before the room has warmed up, the Tado solution to use the offset feature doesn’t work for me, or I suspect anyone.

I have managed to get my smart TRVs to work as they should by using an Oventrop 1011450 adapter that rotates the smart TRVs by 90degs so they are horizontal, this adapter can be fitted to the existing valve without the need to do any plumbing like drain down the system. Rooms I have added the Oventrop adapter to now work perfectly, just as well as using a separate temperature sensor. I have attached a picture of the Oventrop adapter and one of my radiators with the adapter fitted.

The Oventrop adapters cost around £8-9 each (including delivery) if you order 4. The Oventrop adapters don’t appear to be available from UK plumbing merchants (none I tried anyway), but you can get them from ebay and amazon retailers who all appear to be in Germany. Therefore the delivery charges can be quite high, hence it’s best to order several at once to keep the cost down. I used an ebay seller called “ml-haustechnik” (I have no connection with them) who was the cheapest at the time and delivery about 4 days from Germany to UK (eBay item number: 331468588631), but there are other sellers you can choose from. Prices on amazon are higher, although many of the retailers seem the same.

The Oventrop 1011450 has a M30 x 1.5mm fitting at both ends, this is the same as the Tado TRVs so you won’t need to use any of the Tado adapters if the Tado TRVs fit on to your radiators. If you currently use an adapter, then you will still need to use the same adapter to fit the Oventrop adapter to the radiator, the Tado TRV will fit directly on to the Oventrop adapter. Oventrop do make another version of this adapter with different fitting, I think it is part number is 1011460, so just be careful you are ordering the right one.

I have not been able to find anyone else who makes anything similar in the M30 x 1.5mm fitting (Dandoss make some similar for their TRV connection type), so if anyone can find a cheaper alternative, please post-it.

I have vertical Tado TRVs fitted to all my radiators including the ones I have fitted the Oventrop adaptors to. The vertical TRVs work normally when positioned horizontally, the only difference is the display is read from the radiator end in the vertical TRVs which is slightly less convenient in the horizontal configuration.

I think the Oventrop adapters work because the Tado TRV temperature sensor is both further away from the radiator, and is facing away from it. Therefore, the “radiated” heat from the radiator doesn’t cause the Tado TRV to heat up and trick the sensor into thinking the room is hotter than it is. The Tado TRV can now measure the room air temperature through “conduction” heat transfer which is what it should be doing.

It is disappointing that Tado still haven’t recognised this problem or created a solution that actually works, but if you still want to persist with the Tado offering, then this approach worked for me and is cheaper than purchasing separate Tado sensors for each room.

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  • Great suggestion. Thanks
  • Thanks for posting this. Useful to know.

    How do the adapters affect the noise that the TRVs make? Quieter? Noisier? Or no noticeable difference?

  • Hi jcwacky, I only found these adapters because I was looking for an adapter that might deaden the sound transfer to the radiator. Unfortunately, they don't have any noticeable impact on the noise level from the TRV, but I can't tell if the adapter reduces the noise transfer to the rad. I am considering if I can create a sound proof box around the TRV, but sound proofing is tricky, any tiny gap or flaw will let most of the noise out!

  • Amazing! Thanks so much for sharing - I've ordered 5. Also found them listed on Amazon UK as "Oventrop Angle Adaptor/Screw Connection M30 x 1.5 mm" without the model number for a reasonable £7.00 but with the catch of £16.32 international delivery. So I went with your eBay suggestion instead.

  • I've ordered 2.........gonna give them a trial in a couple of different rooms. Worth the cost for a trial 😎

  • RichF, if you put a sound proof box around the stat, you will also stop it from sensing the room temperature, so defeating the point of the TRV. By the way love the valve solution, will definitely try it as I have a couple of bedrooms that rely on TRV temp sensing only and are running with an offset at the moment.

  • Hi Badfly, you are right re sound proof box, my plan was to use an external temp sensor for rooms that I want the TRVs to be quieter, like the bedrooms, I was hoping that for these rooms the Opentrop adapter would prevent the noise being transmitted to the radiator so defeating the purpose of the sound proof box. For all other rooms I don't mind the noise so I just use the Oventrop adapters to improve the temperature accuracy.

    It will be good to hear from others if these adapters work as well for them as it does for me. I have them on several rads of different types and rooms of different sizes and so far so good.
  • I did a similar thing by fitting the TRV itself horizontally (you need to drain the system)
    I guess it works fine

    However it only helps if the TRV is at the bottom of the radiator
  • Thanks RichF, great discovery. If only an equivalent could be found in the UK.

  • Nice idea! Not very visually pleasing though - unlikely to pass the wife test for me. I think I will wait and switch the valves around next summer - although the ones that I already have mounted horizontally are still far from accurate :/
  • Well I have found out what it seems to be physical heat transmission from the Radiator pipes to the Tado Smart TRV. Picture below shows a test I did and what a surprise, the temperatures were off by around 1 degree even with the temperature sensors being far apart ~1 cm. This tells me for sure it is not just a problem of proximity but also of physical contact.

    What I have done is to create a even increased plastic buffer and move far apart the temperature sensor away from the heat source. Virtually avoiding the metal part to heat. I did this with a slight hack of the adapters that came with the TRV (My valve normally does not need any adapter and attaches directly), I had to artificially increase the diameter of one of the adapters and add PTFE to create some padding to make sure the valve will not fall off. If only Tado provided and adapter/buffer/extension out of the box.

    After I did this the temperature reading improved slightly more but not massively. This reveals more about the design issue of the Smart TRV.

    My last test below reveals the following:

    During heat peak (same time):

    Mounted TRV: 21.4C

    Unmounted TRV 1: 20.6

    Unmounted TRV 2: 20.4

    It is that temperature calibration is needed (cannot do it by 0.1C steps) or the physical issue is bigger than expected.

  • Thanks @ChristianG This explains why the only radiator in my house with an adaptor needs the least temperature compensation

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