Tado Extension Kit install

[KSS_1977]

Hi All,

After a bit of advice here, I am a tado user and have had the smart radiator valves and smart thermostat for approx 2 years..

The heating system is an S plan system with HW tank in the loft and a Potterton Netaheat 80E which is old but works ok.

The system was previously controlled by a sunvic timer / programmer. when I installed the smart thermostat it replaced my honeywell room stat, the sunvic timer was set to constant ' ON' for CH and HW was managed by this timer on a schedule.

Slowly I added in tado rad stats for the TRV's and the system was working OK.

Now I have added in a extension kit as I also want to control the hot water with tado ( which works) but also herein lies the issue. It would appear ( with constant back and forth from Tado) that a tado rad stat cannot tell the extension kit AND the smart thermostat to demand for heat.

So essentially what happens is bedroom 1 calls for heat, this goes to the extension kit, and then tries to run it to the boiler ( but the wired smart thermostat is in the circuit) this relay ( in the smart thermostat) does not make the connection and the boiler doesn't fire. I've spoken at length to tado and they said I need to consult with an electrician, in fact their response was the standard cut & paste

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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:

1. 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.
2. You can discuss with an electrician to have your heating system rewired so that it functions as either system a) or b) mentioned above

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My question is, if the extension kit is now calling for the demand from the other devices ( as this has become the primary ' brain' and is switching the heating circuit on and off, is it just a case of the connection that the smart thermostat was making, just needs to be bridged?

More specifically NO & COM ( or rewired at the junction box, but for arguments sake)

This would effectively make the smart thermostat wireless ( as it has it's own internal battery) and send the signal for demand from the Extension kit to the 2 port valve for CH and fire the boiler accordingly.

Hope this makes sense!

Thanks in advance.

 

[stem]

I've installed a couple of extension kits, but not with TRV's. However, what you propose sounds quite reasonable to me.

Provided that the extension kit has been wired in as a direct replacement for the Sunvic programmer, and that as it was wired before when the thermostat was 'on' if you turned off the heating at the Sunvic the heating went 'off', which I'm assuming it did, because you said.

the sunvic timer was set to constant ' ON' for CH

In which case if you configure the room stat to work wirelessly with the extension kit, then put both of the wires that are now in 'COM' and 'NO' into one of the free parking terminals (to the right of the blue wire) then the room stat and TRV's should all be able to work via the extension kit.

 

[KSS_1977]

I've installed a couple of extension kits, but not with TRV's. However, what you propose sounds quite reasonable to me.

Provided that the extension kit has been wired in as a direct replacement for the Sunvic programmer, and that as it was wired before when the thermostat was 'on' if you turned off the heating at the Sunvic the heating went 'off', which I'm assuming it did, because you said.

In which case if you configure the room stat to work wirelessly with the extension kit, then put both of the wires that are now in 'COM' and 'NO' into one of the free parking terminals (to the right of the blue wire) then the room stat and TRV's should all be able to work via the extension kit.

Hi Stem,

Thanks for the reply, I have now carried this out and it is now working as expected.

Always good to have a second opinion

Thank you for your help.

 

[stem]

Great. Thanks for the update, that will help those that follow looking for help with the same question. As well as me in 6 months time when I will have forgotten

 

[cdm20]

Hi Stem,

Thanks for the reply, I have now carried this out and it is now working as expected.

Always good to have a second opinion

Thank you for your help.

Hi, I wonder if I'm in a similar position to you... Albeit with a slightly different starting point.

We've got an S-plan system and we've had Tado for a couple of years, in the form of a smart thermostat and an extension kit. The Extension kit replaced an old Honeywell programmer and controls both two port valves for the hot water and heating, and the smart thermostat replaced an old dial wall thermostat, and is wired as per your original photo. All works lovely.

We're after adding a number of Tado Radiator thermostats to effectively zone most of the rooms in the house. However everything I've read implies that we'll run into problems as ultimately the smart thermostat is in the loop, and it'll also need to be asking for heat in order for the boiler to fire, due to the way it's wired.

When you rewired your thermostat as per this discussion, did you have to change any of the settings on the thermostat itself in the installer menu? Or did Tado themselves have to change anything about your setup in addition to the rewiring?

As a side note, with our current setup when we request heating I can hear the relay in the extension kit, but I've never heard the one in the smart thermostat, but I assume from the way it's wired (via COM and NO) it must be using its relay too, unless I'm missing something.

 

[KSS_1977]

Hi there,

Did you install the Tado system yourself or was it installed by an engineer?

As you already have your EK installed it may be easier for you, considering your system is already working with an ST & EK.

When you rewired your thermostat as per this discussion, did you have to change any of the settings on the thermostat itself in the installer menu? Or did Tado themselves have to change anything about your setup in addition to the rewiring?

This is a good question and is why I think you will be OK. Tado asked me at the time of installation if my Smart Thermostat was wired or wireless, I reiterated to them several times that it's wired. Hoping that when the CH system calls for heat, that the EK & ST relays would both 'click' at the same time and complete the circuit telling the boiler to fire. Alas, this was not the case and the boiler ONLY fired when the Rad Stat in the hallway ( grouped with the ST) called for heat.

Even now, the ST relay will only click if the hallway is calling for heat (so it's just opening and closing and not completing circuits (since NO & COM are bridged)) Tado informed me that they couldn't make both relays close at the same time and the EK is the only 'controlling circuit' to make it work properl, my heating system would have to be 'rewired to suit' ( hence the bridging )

In your case, it would appear that your system is functioning how I wanted mine to after the install of the EK, adding in a Room Stat for you may be a far easier task.

As a side note, with our current setup when we request heating I can hear the relay in the extension kit, but I've never heard the one in the smart thermostat, but I assume from the way it's wired (via COM and NO) it must be using its relay too, unless I'm missing something.

I would summise that if you cannot hear an audiable 'click' in your ST and it's wired in the same way as mine and works, then your ST relay is permanently closed ( which Tado said couldn't be done) - One way to check would be to remove the screw at the bottom of the ST, call for CH and then take the ST off the wall and see if the boiler stops. If it does, your relay is permanently closed and if it doesn't it's wired differently ( probably at the junction box) which is why I initially asked if you wired in the system or was it an engineer ( who may have bridged it at the JB)

Good luck & I hope that all makes sense!

 

[cdm20]

Many thanks for responding so quickly. In answer to your question, I installed it myself a couple of years ago following instructions provided by Tado. At the time I didn't give much thought to whether both relays were working, I just assumed that they did as everything has been fine all this time.

What worries me based on what you've pointed out is a couple of things:

Either the relay is working in the thermostat and I'm going deaf! Or the relay has somehow failed in the correct state to allow a permanent connection, and so the extension kit is the sole trigger, which just so happens to mean everything still works. Although it may be indicative that the thermostat is on its way out! (Although I assume it must be a latching relay, so perhaps it's configured to stay in the same state? In which case why couldn't they do that for you?).

The other final option, which I will double check later, is if as you say somebody has bridged the connection at the junction box, which would've been the previous owners. Although not sure why they would've as that would've made the old rotary wall stat irrelevant, but I shouldn't rule it out!

 

[KSS_1977]

Many thanks for responding so quickly. In answer to your question, I installed it myself a couple of years ago following instructions provided by Tado. At the time I didn't give much thought to whether both relays were working, I just assumed that they did as everything has been fine all this time.

What worries me based on what you've pointed out is a couple of things:

Either the relay is working in the thermostat and I'm going deaf! Or the relay has somehow failed in the correct state to allow a permanent connection, and so the extension kit is the sole trigger, which just so happens to mean everything still works.

Although it may be indicative that the thermostat is on its way out!

No worries , according to Tado, the relay seldom fails.

From our experience we know that our relay in the Smart Thermostat is very reliable. And in the very rare cases where it fails, it fails 100% of the time.

(Although I assume it must be a latching relay, so perhaps it's configured to stay in the same state? In which case why couldn't they do that for you?).

Indeed, this was the basis of my argument with them (same state config) Else why would they need to know if it's wired or wireless? Since it's battery powered anyway, it's just going to be a case of if that relay is doing anything or not. Yet, they made a point in asking me about this.

I'm guessing in your case they knew from the off, that it was a EK & ST install at the same time. As such, it was probably configured so that the ST is relay is closed and the EK relay does the work.

Otherwise, as you point out, it would have never have worked

I guess from their point of view, if they can get systems hardwired so only one relay is 'doing the work' in the system, it's less things to go wrong from their end. Perhaps their installation procedure has changed now and they are less likely to bend over backwards to get their system to work, without some rewiring. ( they used to be very helpful)

In your case, if theres no wiring changes in the JB , I think it's a case of the ST relay is latched closed and you should have no issues moving forward.

The other final option, which I will double check later, is if as you say somebody has bridged the connection at the junction box, which would've been the previous owners. Although not sure why they would've as that would've made the old rotary wall stat irrelevant, but I shouldn't rule it out!

Always worth checking, my old honeywell used to have an amber light on it if it had 'clicked' so I know it was in use ( or at least was connected)