What an idiot!

Tim_F

I've bought a starter kit with smart room thermostat and bridge (successfully fitted) and some radiator thermostats. Being an idiot I didn't check that my existing thermostatic radiator valves were compatible with the tado ones and they're not - they're Pegler Mistral II. Will I need to have these replaced before I can install the tado smart valves? If so any suggestions as to what I should replace them with? Thanks

GrilledCheese2

Yes, a heating system will need a bypass that prevents the water circuit from being fully closed. Historically this was done with a single radiator, but today it is done with an auto bypass valve. The valve is normally closed but opens when the TRVs close, due to the difference in water pressure. The auto bypass valve can be fitted on the pipework outside the boiler, or some boilers have an internal bypass.

You may still need your bypass radiator. It depends how your heating system has been updated in recent years. Probably need a plumber to determine where your bypass is and whether you can have TRVs on all radiators.

If you do fit a TRV in the same room as the wall thermostat then group the two together in the App. The TRV will be controlled by the wall thermostat to accurately regulate the temperature in the room.

GrilledCheese2

Replace them with a TRV that has a M30 x 1.5mm thread. Personally I’d use Honeywell or Drayton, but it depends what is available in your region.

https://tado.vanillacommunities.com/en-gb/home/leaving?allowTrusted=1&target=https%3A%2F%2Fcdn.brandfolder.io%2F607DGEMS%2Fat%2Fwngg83j9q93x6s7qn93hzs7%2F0130_B_SRT_Compatibility_Guide_EN.pdf

%PDF-1.7 % 518 0 obj > endobj xref 518 68 0000000016 00000 n 0000002242 00000 n 0000002373 00000 n 0000003771 00000 n 0000003814 00000 n 0000003953 00000 n 0000004091 00000 n 0000004230 00000 n 0000004367 00000 n 0000004933 00000 n 0000005693 00000 n 0000005730 00000 n 0000005985 00000 n 0000006097 00000 n 0000006211 00000 n 0000006731 00000 n 0000006993 00000…

Tim_F

Thanks for the reply - looks like I'll need to spend some more money and get the TRVs changed to get the tado system fully up and running.

Another question if you don't mind. The room where the wall thermostat is fitted has a radiator with no thermostatic valve so is permanently on when the heating is switched on. I assume this is some sort of by-pass system. Do I need to leave this as it is or can this be fitted with a TRV as well?

RichP100

Looks like I’ve done same 🥲

NicB

Tim_F did you find a solution for the Pegler Mistral II TRVs? I’ve done the same, although I have realised my error before trying to fit them. What was the additional cost to get the plumbing works done? I’m trying to work out whether it’s feasible to get the works done now or return the TRVs to Tado and re-buy at a later date when I can afford the plumbing works. I’m kicking myself.

pcone

May be worth trying to fit them?

I have Pegler Terrier TRVs which are listed as not working, but have actually worked fine in my house for over two years now. They're listed in the same box as the Mistrals on the compatibility chart: https://cdn.brandfolder.io/607DGEMS/at/wngg83j9q93x6s7qn93hzs7/0130_B_SRT_Compatibility_Guide_EN.pdf

Tim_F

Hi NicB. In the end I bit the bullet and bought replacement valves and got my plumber to change them. Cost a couple of hundred quid but I'm glad I did it now (although it hurt at the time!). The tado valves are great and heating the house so flexible and much easier to manage using the app.

pcone

Actually, I recall some discussion on here about the Tado heads not physically fitting due to the shape of the Pegler valve. Doing some Google searching, I think the Terriers have an octagonal base (between the brass valve and the thread), but the Mistrals have a square base. I wonder if it's the square base that causes the issue, but worth checking what shape yours are...

NicB

Thanks everyone. I will double check the shape of the connection on the Mitral II, but suspect it won’t be compatible. I’ve watched a few YT videos on how to replace radiator valves and the process looks fairly straightforward (famous last words), so I shall have a go at doing it.