Remove redundant thermostat and power Smart Home Hub instead

[Susi]

Hi, I have installed a Tado system by replacing a couple of old fashioned Honeywell thermostats. Everything is working fine. However, I still have two old Honeywell Thermostats which are redundant - they control a heating circuit each (for each floor) and are always "on", and the Tado room thermostats now actually control the heating.

I would like to get rid of the old Honeywell thermostats as they don't serve a function anymore and are ugly. In addition to this, I would like to use the existing wiring for the thermostat to power a Samsung tablet for a smart home hub. Is that possible? In other words, I would like to remove the old Thermostat, change the wiring that heat is always on (without actually having the thermostat mounted), and use the wires/electricity to permanently power a Samsung tablet. How can I do this? Any ideas? I have quite limited knowledge of electric circuits and connections. I have attached a picture of the current 1-channel Honeywell thermostat which I would like to get rid of.

I am aware that it is probably not best practice to power a consumer unit through the heating circuit, but bear in mind that we are talking about powering a 7 inch tablet, not a vacuum cleaner. I am looking forward to your thoughts or inputs. However, if you think that powering the tablet through the heating circuit is silly, there is a light switch next to the thermostat - maybe the tablet can be powered from that instead? However, I still wouldn't know how to do that as I somehow would need a socket to connect the tablet charger and USB cable to it, and I don't want these things to be visible. And the thermostat wiring would need to change as well.

 

[SPECIAL LOCATION]

Welcome to the forum...

What you want to do may be possible...

BUT the big problem is that fact that there is NO standard wiring method for heating control circuits...
(e.g. cables / colours used can often be down to the personal preference of whoever first installed it)

Often there will be a large junction box / heating control centre, where all the individual cables from Supply, Boiler, Thermostats, Motorised vales etc.. are all connected together..

It may help, (or may not), having a photo of this box with its lid off?

 

[michael8554]

Appears to be a Honeywell ST9100C.


When you take the face plate off there's a diagram on the back plate.

 

[Susi]

What you want to do may be possible...

BUT the big problem is that fact that there is NO standard wiring method for heating control circuits...
(e.g. cables / colours used can often be down to the personal preference of whoever first installed it)

Often there will be a large junction box / heating control centre, where all the individual cables from Supply, Boiler, Thermostats, Motorised vales etc.. are all connected together..

It may help, (or may not), having a photo of this box with its lid off?

Thank you for the welcome. I have attached photos from the heating control centre above to my first post. To my understanding I have two heating circuits, one for the ground floor and one for the first floor. The ground floor is controlled by a Honeywell ST9100C 1-channel programmer which is always on after having installed Tado wired thermostats to control each room on the ground floor.

 

[Susi]

Appears to be a Honeywell ST9100C.

View attachment 15753
When you take the face plate off there's a diagram on the back plate.

Yes, it is a Honeywell ST9100C 1-channel programmer.

 

[Geoff1946]

That's a lovely neat wiring centre; They usually resemble something built by a rodent.
Is it an underfloor system? The item half on the picture looks like a UFH manifold with control valves.

I'm a bit puzzled as to how you are controlling the system; my ignorance as I've never heard of Tado.
However, to focus on your question, everything you want is there. The programmer live and neutral are just that and would feed any low power item. The ON command is simply the two relevant wires being connected together, (one of which is probably the live supply).
The outstanding question is how you do it physically to look neat. It looks like the programmer is over a flush box, so a surface item could be fitted over it leaving all the redundant wires behind it.

 

[Susi]

That's a lovely neat wiring centre; They usually resemble something built by a rodent.
Is it an underfloor system? The item half on the picture looks like a UFH manifold with control valves.

I'm a bit puzzled as to how you are controlling the system; my ignorance as I've never heard of Tado.
However, to focus on your question, everything you want is there. The programmer live and neutral are just that and would feed any low power item. The ON command is simply the two relevant wires being connected together, (one of which is probably the live supply).
The outstanding question is how you do it physically to look neat. It looks like the programmer is over a flush box, so a surface item could be fitted over it leaving all the redundant wires behind it.

Yes, the ground floor has underfloor heating. The first floor has radiators. I understand that I have two separate heating circuits to control these.

Tado is a competitor to Hive and other smart control producers. I just have a preference for German manufacturers, so I went with Tado. I have three Tado smart Thermostats on the ground floor controlling the underfloor heating, and a few Tado smart radiator thermostats controlling the radiators on the first floor. There is a Tado hot water/heating control unit connected to the boiler, I have upgraded it from a Honeywell STC9400 2-channel programmer earlier. The Tado system is working well. I can fully recommend it and even a dummy like me managed the self install as they have detailed installation videos.

Are you saying that I need to change something in the main heating unit? There are 4 wires to each Thermostat Zone 1,2 and 3. (I actually thought I have 2 zones?)

With regard to the programmer, it is just screwed to the wall and the wires come out of an app. 2x2 inch hole. Yes, I am both interested in how to wire this, and how to do it physically neatly. Again, there is a light switch next to the Honeywell programmer if that is better to power the tablet. Should I perhaps change the wiring at the main unit to put the programmer "always on", and just close the existing hole in the wall, i.e. bury the wires? I could then power the tablet from the light switch (somehow).

With regard to the physical appearance, I thought to install the tablet in a frame like e.g. this one. I could probably hide the wires behind that. The seller also suggests different charging options (click on the 3rd picture).

https://www.etsy.com/uk/listing/703...nt&ref=sr_gallery-1-10&organic_search_click=1

 

[BorisJ]

You cannot simply bury live wires.
You probably cannot power from a light switch as there is probably no neutral at the switch.

 

[Susi]

You cannot simply bury live wires.
You probably cannot power from a light switch as there is probably no neutral at the switch.

I don't think that I have suggested to bury live wires. I said that I could perhaps make the required wiring changes at the central main unit to change the circuit to always "on", and then cover the hole with the non-live wires after that.

The light switch wiring looks as attached. There doesn't seem to be a neutral wiring, but it's hard to believe that I can't use the existing wiring to additionally power a tablet.

Apologies if I am misunderstanding anything, I don't know a lot about electricity, but I have good reasoning skills.

Can't I use a Volt converter like this one?

https://www.amazon.co.uk/Isolation-...6&sprefix=240v+to+5v+converter,aps,111&sr=8-6

 

[SPECIAL LOCATION]

From what I can see on your photos, I would assume there are single direct 3core+E cables from each of the thermostats back to the wiring centre.

These could be physically removed from the wiring centre and reconnected externally to a separate supply.. (e.g. via 5A fused 3pin plug)..

Then where your old thermostats are you could fit a USB charger plate, , which is what I assume your tablet(s) would need to keep them powered?
(may need a deeper back-box fitted?)

e.g. quick google brought up something like this..
https://www.cef.co.uk/catalogue/pro...ket-charger-stainless-steel-with-black-insert

(Think these things tend to come with multiple USB outlets, even though you only need 1 socket)

You would need to shop around as as a general rule CEF are not the most cost effective supplier!!!

 

[Susi]

From what I can see on your photos, I would assume there are single direct 3core+E cables from each of the thermostats back to the wiring centre.

These could be physically removed from the wiring centre and reconnected externally to a separate supply.. (e.g. via 5A fused 3pin plug)..

Then where your old thermostats are you could fit a USB charger plate, , which is what I assume your tablet(s) would need to keep them powered?
(may need a deeper back-box fitted?)

e.g. quick google brought up something like this..
https://www.cef.co.uk/catalogue/pro...ket-charger-stainless-steel-with-black-insert

(Think these things tend to come with multiple USB outlets, even though you only need 1 socket)

You would need to shop around as as a general rule CEF are not the most cost effective supplier!!!

Thank you, this is very helpful. I am happy to google around once I know what is needed.

I was thinking to install a standard power socket fed from the main switch, and then to plug in a charger for USB into that socket. Do you think this is possible? I have marked this in orange in the attached picture.

With regard to the existing wiring: Do you mean that the area in green marks the thermostat circuits?
I need the circuit feeding the Honeywell programmer to be always on, even after it is removed physically. Is my understanding correct that the connections in the green circles are the actual thermostats, while the Honeywell programmer is wired in series between the actual thermostats and the motorised valve?

I am asking because I need to either bridge the existing Honeywell programmer, or have it always on as the Tado controllers do the work now. At the moment the Honeywell programmer is just always on. I would like to go one step further and remove the programmer, however, do I have to do the bridging in the heating centre to make this work? Is that possible? If so, where would I have to do this?

https://support.tado.com/en/article...ridge-my-existing-room-thermostat-or-receiver
Maybe it's also worth going a step back: Are you able to identify what sort of wiring system I have? Is it Y or S or any other wiring? Once I have that I am happy to educate myself on the circuit and on the use of the wires.

 

[Murdoch]

That isolator is purely that a 3 pole isolator which is fed from elsewhere.

Are you sure you know what you are doing?

 

[SPECIAL LOCATION]

I was thinking to install a standard power socket fed from the main switch, and then to plug in a charger for USB into that socket. Do you think this is possible? I have marked this in orange in the attached picture.

[1] No I would consider your "main switch" idea as a bad choice.
[2] I would be looking to keep ALL heating control supplies and wiring separate from any tablet supply wiring.
[3] I would not contemplate using a standard socket + charger.. poor solution IMHO..
[4] See my previous post..

e.g. Assuming you can confirm 100% that there are individual direct cables to the thermostat positions:-

These could be physically removed from the wiring centre and reconnected externally to a separate supply.. (e.g. via 5A fused 3pin plug)..

Then where your old thermostats are you could fit a USB charger plate, , which is what I assume your tablet(s) would need to keep them powered?

Why would you want a 3-pin USB charger, when an integral USB faceplate can do a neater job..?

You probably need a competent electrician to pop round and verify exactly what you do have and what is feasible, as heating wiring can often have a few non-standard lash-ups that are not always noticed on first investigations...

And the heating controls are still using 230v mains voltage that can kill a healthy adult in less than a second!

First course of action should be, get old thermostat wiring disconnected,
do any strapping, alterations to make sure the whole of the heating system is still working OK via the new Wi-Fi, kit...

Then you can look at re-purposing the old thermostat cables as tablet USB power supplies.

 

[Susi]

Thank you very much for your help. I can confirm 100% that there are 3 individual direct cables to the thermostat positions on the ground floor. There is an additional (fourth) slot to the Honweywell programmer - that 's the unit I would like to get rid off.

The Tado smart thermostats which I have installed a year ago are all wired - it's not all wifi. They are wired to the three thermostat positions on the central heating board/switch, and should remain there. The wifi aspect of the smart thermostats is only to introduce a remote control/time programming via an app - other than that the Tado thermostats remain connected to the central heating board/switch, so I shouldn't remove that wiring. The wiring which I would like to remove pertains to the Honeywell programmer (which is simply a timer for the underfloor heating thermostats - regardless of whether they are smart or non-smart)

I also found out that the central heating switch/board (that I have posted photos of) only controls the underfloor heating downstairs. I was wrong to assume that the central heating switch/board controls the entire house. There is a second/separate control board which controls the radiators on the upper floor. So the pictures I have sent so far are for the ground floor underfloor heating only - they control three thermostats, one programmer, and 4 motorized valves (1 kitchen, 1 hall, and 2 lounge - all underfloor heating). The three (smart & wired) thermostats are working fine - I would like to get rid of the Honeywell 1-channel programmer (and wiring).

Let me do some further testing and provide you with an update as soon as I have it.

Thanks a lot again for your inputs.