Combining the best of Tado and Nest?

BryanW

I realise the title of this post may sound odd or even controversial but here goes. My system is very conventional (read old fashioned) consisting of a 16 year old Viessman 100 WB1 boiler, gravity fed (tank in roof space) and I believe what is called a Y plan layout with separate two-way valves controlling the heating and the hot water. About ten years ago I bought a Nest 3rd gen thermostat and it was a revelation with it ability to set precise schedules , its learning capabilities and of course its gorgeous looks. Last year things moved on even further with the purchase of Tado Smart Radiator valves to fit most of my radiators (left off the ones in the two bathrooms to allow the water to circulate).

So far so good but as brilliant as the Nest is it does not of course have smart radiator valves as part of its system or have the ability to "talk" to Tado or other systems (for understandable but annoying commercial reasons). To gain this functionality I could of course ditch the Nest and replace it with the Tado smart thermostat. Many on here appear to have done that but I am quite reluctant. In my view the Nest thermostat beats the Tado hands down in every department other than smart radiator valve integration. It looks better, it is better built , the Farsight facility is really useful etc etc.

So, how to resolve this quandary? It then occurred to me what if I kept both? My first idea was to just have the Nest "receiver" (the hard wired bit) powered up with live and neutral (and earth if there is one) simply to act as a transformer to the Nest thermostat. However the switching would be done by the Tado receiver (same live, neutral powering it as the Nest) but with the actual on/off for the hot water and central heating done by Tado using its receiver and (wireless) thermostat. The latter could be in the vicinity of the Nest thermostat and would be doing the work but I would assume the Nest would continue to show the temperature, whether it is heating or not etc since it does not know that it is no longer connected to the boiler.

Having got so far my second thought was why bother with the hot water control on the Tado since the Nest performs that function the same - so just leave that as it is and have just the central heating controlled by the Tado.

My final thought - and it has only just occurred to me while typing this is why not duplicate everything between the two receiver boxes. So either or both can call for heat at the same or different times. Presumably the boiler won't know or care where it gets its power from. This way ensures that the Nest continues to be useful and the Tado is there to provide the smart integration with the valves.

Any thoughts anyone? Am I completely mad? The cost after all- of buying the Tado thermostat will be the same if I am replacing the Nest or have it running alongside the Tado.

I can't think the electrics will be a problem since it will be the same live and neutral going to their respective terminals in both receiver boxes and the same outputs to the central heating part of the boiler (I won't bother to duplicate the hot water) so the boiler will simply respond to the first box to turn it on and the last to turn it off.

I hope I have described things clearly enough for you to comment - if you wish.

BryanW

I thought I would update this thread as I have since bought a further three Smart Radiator valves and, most importantly the wireless thermostat and receiver (with yet another Internet Bridge so I now have a spare.) I wired the receiver up simply by "bridging" the live and neutral from the Nest to the same terminals on the Tado (they are virtually identical). In the end I chickened out of mirroring all the connections and so disconnected the feed to the boiler/central heating valve from the Nest and connected it to the equivalent terminal on the Tado. I left the hot water connections on the Nest since it works well on there and the Tado offers me no additional functionality. The process was simple and quick although I did have a problem getting the wireless receiver to connect to the Internet Bridge despite following the instructions to the letter. In the end I put the bridge into pairing mode (not mentioned in the instructions) and hey presto, connection. All fired up as expected.

The good news is that I now have control of the central heating through the Tado system (so unlike the Nest individual rooms/radiators can call for heat as needed) but I also have the Nest thermostat still showing the current temperature, Farsight still works, and when Nest "thinks" it is calling for heat the display goes orange as before. The two thermostats are close enough and set to the same temperature and schedule to each other so that for all intents and purposes the Nest continues to be the display we use. I have made no secret of my dislike for the Tado thermostat and this just sits on a shelf nearby. I have made my wife aware that she can no longer wizz the Nest thermostat round if (when!) she feels cold and she is happy with that. We don't in any event use the Nest much for that as we tend to control things either via the app or by voice commands (Google). So far this is working OK.

The one thing that Nest does not appear to be replicating with any accuracy is the amount of energy used in the "history tab". It has only been one day and so too early to say but my guess is that Nest is calling for heat more than Tado and it is therefore showing an overuse of gas. It may only be my imagination but Tado seems to offer a "gentler" rise in temperature (witness the three wavy lines on the heating screen) whereas Nest was simply on - full pelt - or off.

The main reason I did not wire them both in parallel was because I read somewhere that boilers needed to have a period of hysteresis which they may not be able to get if they were being "fed" from two thermostats. So far I have not been tempted to add the Nest back in and the system as it now is is close to perfect for my needs.

One thing we have noticed is that the upstairs is warmer with the Tado system. We do have a wood-burning stove which gets lit on cold nights and/or weekends. With the Nest system the thermostat was shutting down the whole central heating once the stove got warm and the heat reached the thermostat in the adjoining hall. The radiators upstairs however were being shut down so it could be on the cold side when going to bed. The Tado avoids that problem absolutely since individual rooms can respond as their settings determines.

Sorry this has been long-winded but if it helps anyone thinking of doing the same then I am happy.

Bryan

PS. Tado products are available cheaply at the moment from Screwfix (and no doubt others) because of Black Friday deals.

Tewy59

Very useful Bryan, thanks very much. I've been pondering this issue for a little while now. It just seemed a shame to ditch a Nest system to get better control of room my room schedules. The fact that you run the 2 in parallel makes sense, but I think I may as well ditch the nest altogether, even though, like you, I think the nest is so much nicer looking than the Tado thermostat controller.

Leo_Gr

I had the nest(i am sad because i had to return it due to a common malfunction in it’s wifi board) and i have to say that its Ai feature will learn your home in some weeks and will provide you with better economy and gas consumption than tado.I have the tado for 2 weeks now and it doesn't t have any AI technology.Nest is indeed a learning thermostat.The bad thing is that since nest was sold to Google they announced some years later that they will stop investing in the product

BryanW

We are agreed that Nest is a "learning" thermostat ( by which I take it to mean it calculates how long it takes to heat your house over a period of days/weeks and then through some clever algorithm in its servers which take account of the weather forecast for your area applies that so that the house, or the room, has reached the temperature you want at the time you want it). What surprises me is your assertion that Tado is not self-learning. (which is what I understand from your statement that Tado has no AI technology). Agreed, I can find nothing in the Tado literature (albeit from a very quick internet search) where Tado claim it is self learning but at least one reviewer (Good Housekeeping) claims it is when it declared "When we tried the system, we were impressed by the self-learning and how it effectively amended our schedule." (review dated November 2023). Can you please advise me on what basis you are making your assertion, or for that matter if anyone on here reading this - and preferably someone form Tado themselves - can clarify this point. I hope that your view is not based on two weeks of usage which surely cannot be sufficiently long enough to form any meaningful conclusions.

johnnyp78

Tado is not self learning in the way that nest is when it comes to altering schedules. What it should learn to do is learn how long rooms take to get to target temperature and how long they remain at target temperature before it starts to drop, rather than just heating to the target temp and switching off the boiler like a dumb thermostat.

Nirwin

I have been using tado for 3 years and am considering replacing it because it has not ever 'learned' anything. It overshoots everyday, sometimes by more than 1 degree and sometimes hovers at half a degree below setpoint. I've had enough of overheating and my wife has had enough of being cold. By the way, my wife doesn't use it, she voice commands me to adjust it. I realised early on that the early start function was useless as it was bringing the boiler on an hour and a half before required and then overshooting 25 minutes later...still more than an hour before required. The boost function is also a waste as 25 degrees for half an hour resulted in my house being 26 degrees after 20 mins. I addressed all this with the help team early on and got fobbed off with explanations that made no sense. I made the best of it with clever scheduling, heating for 15 mins and then turning off for 25 mins to allow radiators to raise temperature. I also created shorter boost functions of 5 and 10 mins for when it allowed the rooms to get too cold. Works partially but it's more like being manually controlled. Worst thing I can say is that it is terrible at maintaining accurate temp which should be its main purpose.