Yet Another 3-Channel Replacement Question

jdku2003

I know there are quite a few people that ask this, on various forums, but, despite following a number of the answers I'm unable to make my particular setup work.

I have replaced a 3-channel ESI controller with an Extension Kit, then replaced the two ESI thermostats (upstairs - master bedroom and downstairs - hallway) with Smart Thermostats. All this has been working fine since Tado support: "We have configured your device to work as a relay thermostat. When tado° calls for heat, the relay is closed and there is a connection between NO and COM."

Now I've purchased some Smart TRV's and this is where it's falling down. With the base setup, the radiators can only call for heat if the Smart Thermostat in that zone is already calling for heat. So, back onto support and received the following:

"From the information you have provided us with, we understand that you would like to add Smart Radiator Thermostats to your current heating system, and that this heating system has separate zones controlled by zone valves (often referred to as motorized or 2-port valves).

Currently the installation of Smart Radiator Thermostats on multi-zone homes is possible if your heating system consists of either:

a) zone valves which are controlled by wired thermostats that send a call for heat directly to the boiler, or

b) where there are only two zones, one controlled by an Extension Kit, and the other wired directly to a Smart Thermostat.

Our Smart Radiator Thermostats are able to call for heat from the boiler because it not only opens the radiator valve, but also asks the Smart Thermostat or the Extension Kit to send a demand for heat to the boiler.

It is not possible, however, for the Smart Radiator Thermostat to ask the Smart Thermostat to ask the Extension Kit to call for heat.

Therefore, if your heating system has any other configuration (e.g. more than one wireless thermostat, or none of the thermostats are able to call for heat without a timer or programmer set to "on"), then you have 2 options:

We can configure the Smart Radiator Thermostats so that they simply run a schedule when someone is at home. They will not be able to call for heat from the boiler, but only open/close the radiator.

You can discuss with an electrician to have your heating system rewired so that it functions as either system a) or b) mentioned above."

This appears to be a fairly stock answer from Tado (quite a few people have heard the same thing) and as much as I'd like to take their word for it, in that it needs an electrician to make it all work, it was Tado that also told me to send everything back as I couldn't have Tado replace a 3-channel controller, which is obviously not true.

So, I followed this: https://www.diynot.com/diy/threads/tado-extension-kit-install.538180/ which seemed to be having the same issue. But when I came to move the wires on the Smart Thermostats, I have four wires, not three. I suppose I could just tape up the earth and then move everything else into the spares. I did this with the downstairs one, set it to TS in settings, but when a radiator downstairs called for heat, it switched the whole of the upstairs on...I don't know if Tado would need to reverse what they did on the Extension Kit? Support (live chat) didn't know either, which is handy.

I still need the Smart Thermostats at the moment as two of the radiators don't have any TRV's at all. But, if they're what's causing the problem I'll happily get rid and get someone to fit TRV's to those rads.

[Deleted User]

Hello jdku2003,

Thank you for your question,

However you have already provided the answer to your own question.The tado° Installation team first recommended not to proceed as your set up is not compatible. In agreement a compromised configuration was created. As a result any addition to this set up will not work. Which leads back to the initial findings of the tado° Installation team, your current heating set up is not compatible.

To allow tado° to be compatible it would require a complete rework of your system. Only then (when two channels are enough to control the boiler, Hot Water and all valves) can the configuration of the tado° be completed to make it work as required.

As it stands, regardless of any other suggested work-arounds, tado° cannot replace a 3 channel set up

Kind regards,

Joey