I am looking to replace my current heating set up with a smart system. Specifically from here https://uk.store.tapo.com/collections/temperature-humidity-monitors because its in the sale and we already have their smart sockets!
This is for the upstairs of the house that is on a separate circuit to the downstairs underfloor heating system.
Currently we have the control unit for the Hot Water and heating in the utility room downstairs I do not want to replace this if possible. Upstairs there is a wired Thermostat in the hall which I assume would need to be replaced, but I cannot see a Tapo device to replace this with. All the radiators upstairs would then get a Smart TRV. What I don't understand is that without a smart thermostat if the hallway reaches temperature the heating would turn off even if other rooms were requiring heat? I could up the temperature cut off for the Thermostat and using a Smart TRV on the halls radiator not allow that room to ever get to the thermostats set temperature? But if I do this all the TRV's could be off as they have reached temp but the wired thermostat is still telling the boiler to send heat around which can't be a good thing.
There must be something I am not understanding? Or do I need a different system with a smart wired thermostat?
Not sure about the Tapo system but we have a hive with smart TRV which can be set to either head based on the main thermostat controller, and/or heat on demand for any of the smart TRV's. for example, if I'm the only one in the house and I'm working in my office, I can set the office TRV to heat on demand and the main thermostat to a comfortable low. That way I get heat where I want it.
problem is, and I think you’ll find that it's the same with the Tapo, is that any radiators that don't have smart TRV will be on when a smart TRV is calling for heat. so potentially, if a smart TRV is calling for heat upstairs, downstairs radiators will also be on.
IME the best way to run these systems is to have all radiators with smart TRV's, we don't. our hallway, kitchen and bathroom are normal valves, but I'm happy for those rooms to be heated even if the main thermostat isn't calling for heat.
so potentially, if a smart TRV is calling for heat upstairs, downstairs radiators will also be on.
..... if they are on the same circuit (but not if upstairs is on a separate circuit to downstairs.
Upstairs there is a wired Thermostat in the hall
Your hall is upstairs?
I don't have a smart system but I thought the smart TRVs on each rad removes the need for a 'central' thermostat as each room effectively has its own.
IME the best way to run these systems is to have all radiators with smart TRV's.
How do you deal with the radiator on a circuit that is 'permanently open', so should not have a TRV fitted?
Hi Thanks for your reply.
I think you sort of understand my issue/concern. My plan would be to have all radiators upstairs with a Smart TRV. Down stairs is on a completely different circuit and will be unaffected by what I do on the upstairs system. The bit I don't understand is that the original wall mounted wired thermostat in the hallway could conflict with what the smart TRV's want. If I turn up the wall thermostat to a higher temperature than the TRV in the hall this means when the hall gets to temperature heat can still get to the other rooms in the house, but when all rooms get to temperature the wired thermostat will still be calling for heat but it has no where to go.
If I go the other way and turn down the temperature in the hall the heating could turn off with the wired thermostat despite other rooms in the house still wanting heat. I can't see a way round it without replacing the wired thermostat with a smart one. But I don't know if that exists for TAPO, or I am missing something!
I have the Tado system and assumed at a glance this would be a sister company, I don't think it is and although the valves look similar, how much different can rad valves look!
I also dont get the bundles/equipment, as it looks like every valve also comes with a sensor, where as my Tado Valves can sense temperature themselves and ask for heat or switch off.
Hopefully someone who has some can come along and help!
If you have two circuits can't the downstairs thermostat be wired to only run the downstairs circuit?
What I don't understand is that without a smart thermostat if the hallway reaches temperature the heating would turn off even if other rooms were requiring heat?
Upstairs/bedrooms generally require less heat than downstairs so maybe it would be doubtful this situation would arise.
And if it was wired to only control the downstairs circuit then it wouldn't matter.
If you have two circuits can't the downstairs thermostat be wired to only run the downstairs circuit?
That is what already happens, downstairs has its own thermostat in each room. Upstairs has a wired thermostat in the hall and I want to make the upstairs a smart system. I just can't work out how to do it with a wired Thermostat.
Upstairs/bedrooms generally require less heat than downstairs so maybe it would be doubtful this situation would arise.
The downstairs heating is not connected to the upstairs. They have separate thermostats and I won't be changing anything on the downstairs heating. The upstairs thermostat is upstairs in the hall way
I just can't work out how to do it with a wired Thermostat.
You don't need a 'central' thermostat upstairs..... every room would have its own (the TRV) which would talk to the controller which would be fitted where the old upstairs wired thermostat would connect in the utility.
That's why you can't find a thermostat.... you don't need one.
I also dont get the bundles/equipment, as it looks like every valve also comes with a sensor, where as my Tado Valves can sense temperature themselves and ask for heat or switch off.
I was confused by that to begin with, the TRV has its own temperature sensor but you can pair it with a room sensor to give greater accuracy of temperature around the room not just around the radiator. I wouldn't bother with those sensors.
I think you want this kit from Tapo:
https://uk.store.tapo.com/products/kasa-smart-radiator-valve-room-thermostat-bundle
With their room thermostat replacing your wired thermostat.
You don't need a 'central' thermostat upstairs..... every room would have its own (the TRV) which would talk to the controller.
Currently the heating comes on when the thermostat kicks in. How would the TRV talk to the controller? The controller is dumb that is why it has a wired Thermostat.
Or just use one of their smart TRV just left loose in the hall way without connecting to radiator to replace the wired thermostat.
when the loose TRV senses it’s cold it will request heat from the boiler the same way your current wired thermostat does.
I think you want this kit from Tapo:
https://uk.store.tapo.com/products/kasa-smart-radiator-valve-room-thermostat-bundle
With their room thermostat replacing your wired thermostat.
This is what I thought, but I don't know how the room thermostat would talk to the controller to tell the boiler to kick in? Hence why I think I need a wired thermostat? Or do I need a new controller for the heating system?
Or just use one of their smart TRV just left loose in the hall way without connecting to radiator to replace the wired thermostat.
when the loose TRV senses it’s cold it will request heat from the boiler the same way your current wired thermostat does.
But how would the TRV talk to the controller for the boiler? The controller as far as I know has no way of connecting a smart system to it unless I use a smart wired thermostat? Or I just don't understand which is quite possible!
Currently the heating comes on when the thermostat kicks in. How would the TRV talk to the controller? The controller is dumb that is why it has a wired Thermostat.
Surely there is a receiver that is wired to the boiler controller to tell it to start and stop?
Your old wired thermostat is basically a switch that starts and stops the boiler.
A wireless thermostat is made up of two parts - the thermostat (the transmitter) and a receiver which is connected to the boiler controls. When the thermostat says it's too cold it sends a signal to the receiver which [does the same thing as a wired thermostat] and closes the contacts [switch] which then turns the boiler on.
Your smart system is similar to the wireless thermostat except you have multiple thermostats [transmitters] that talk to a single receiver. If any of them call for heat then the receiver switches the boiler on.
Ahh wait, I get it now!
Looks like the Tapo system does not include boiler controller ... I thought that Kasa hub talked to the boiler but it's just a hub for their smart TRVs.
There is nothing in the Tapo product range that talks to a boiler, they can only open or close radiator valves.
I'm not entirely sure I'm convinced with 'smart' heating systems... seems like a lot of effort and money for not marginal gains! What are you trying to achieve OP?
What I don't understand is that without a smart thermostat if the hallway reaches temperature the heating would turn off even if other rooms were requiring heat?
Not Tapo, but that's how our Honeywell Evohome smart system works. Smart TRV on every radiator throughout house, except for bathroom, downstairs WC and my tiny office - so each room and hallway is its own 'zone'. The central controller that's plugged into our router has a thermostat built in but we chose not to use it for the reason you're worried about, so switched it off in settings during setup.
Basically, you don't need or want a central thermostat that could needlessly override the smart TRVs. I assume that could be achieved in Tapo but I don't know that system.
Sidenote: the Honeywell system works great! The app is brilliant with 7-day programmes for each zone/smart TRV. Really happy with ours.
Surely there is a receiver that is wired to the boiler controller to tell it to start and stop?
Your old wired thermostat is basically a switch that starts and stops the boiler.
A wireless thermostat is made up of two parts - the thermostat (the transmitter) and a receiver which is connected to the boiler controls. When the thermostat says it's too cold it sends a signal to the receiver which [does the same thing as a wired thermostat] and closes the contacts [switch] which then turns the boiler on.
Your smart system is similar to the wireless thermostat except you have multiple thermostats [transmitters] that talk to a single receiver. If any of them call for heat then the receiver switches the boiler on.
Yes my current wired Thermostat is a switch, this is why I assume I need a wired smart thermostat to talk to the boiler controller to tell it to turn on the heating. As far as I can tell the Tapo system doesn't directly communicate with the boiler, to get around this my assumption is the requirement for a smart wired Thermostat but it doesn't exist for this system.
It looks like a different system is required.
I'm not entirely sure I'm convinced with 'smart' heating systems... seems like a lot of effort and money for not marginal gains!
I wish I could compare directly for a before/after, but we installed our Honeywell system within 6 weeks of moving into current house so don't have 'before' comparison. However, we moved from a 2007 modern 220sqm 6-bed, to a 178sqm 3/4-bed late-1800s detached villa and our gas usage reduced by just over one third. I didn't expect that moving from a modern new build to an old sandstone house with solid walls and little insulation - we were expecting the opposite.
What't it achieved for us? Reduced gas usage. More pleasant to live in - we have each room programmed to only heat as and when needed, e.g. kitchen/living room heated 7-9am then off again til 3pm when kids arrive home from school, bedrooms only heated from just before bedtime until after normal bedtime, 'posh' lounge we only use in evenings is only heated for the evenings. Can override any programme at any time, remotely via app if necessary. can also set minimum temp if necessary to prevent frost damage etc. Bloody brilliant for us.
Example of a programme:
I assume I need a wired smart thermostat to talk to the boiler controller to tell it to turn on the heating
No you don't need a thermostat (as you call it) at all - that's what the smart TRVs do. You have a receiver that controls the boiler (i.e. switches it on and off).
I'm not sure there are any TRVs that talk directly to a boiler.
I assume I need a wired smart thermostat to talk to the boiler controller to tell it to turn on the heating
No you don't need a thermostat (as you call it) at all - that's what the smart TRVs do. You have a receiver that controls the boiler (i.e. switches it on and off).
^What he says. Receiver is attached to boiler and does the interaction with that. The smart TRVs talk to the receiver. No need for any central thermostat. At least, that's my understanding of our system in layman's terms.
What't it achieved for us? Reduced gas usage. More pleasant to live in - we have each room programmed to only heat as and when needed, e.g. kitchen/living room heated 7-9am then off again til 3pm when kids arrive home from school, bedrooms only heated from just before bedtime until after normal bedtime, 'posh' lounge we only use in evenings is only heated for the evenings. Can override any programme at any time, remotely via app if necessary. can also set minimum temp if necessary to prevent frost damage etc. Bloody brilliant for us.
I'm certainly not going to dispute any of the above.... but you've moved to a smaller house and your heating requirements have gone down 😉
I can see that not heating upstairs until later in the day is beneficial but that could be achieved with a circuit for upstairs and another for downstairs.
There is also the unresolved argument that heating should be on all the time. Who knows!
I did think about it years ago (and the Honeywell system as that seemed to be the best at the time) but just couldn't really justify the cost. I may have been wrong, but now that my three girls have left home I just turn the TRVs down in their rooms when they're not around.
My feeling is that if the boiler is running for one room* then you may as well heat all of them (within reason).
* I can't get my head around the idea that a single room calling for heat entails firing up the boiler!
No you don't need a thermostat (as you call it) at all - that's what the smart TRVs do. You have a receiver that controls the boiler (i.e. switches it on and off).
I'm not sure there are any TRVs that talk directly to a boiler.
With that Tapo system I don't see any receiver that i would attach to my boiler. My current controller does Hot water and heating, do these receivers replace the current controller?
There's a lot of dross on the market that adds the word "Smart" to their marketing and does nothing smart.
I've had Nest and Hive thermostats and their smart credentials are a basic example of enshittification; nothing that is automated comes up with the right answer more often than I'd expect of a dimwitted monkey, with the added bonus of the Hive from time to time losing track of the ability to tell the temperature unless you plonk it in a freezer drawer for five minutes. I've persevered with these because I can check I haven't left the heating on remotely. That's the only actual benefit besides automatically coping with daylight savings.
I've played around with a HomeAssistant TRV automation scheme for a guest annex at home that doesn't get used much and it has its own separate oil boiler. The boiler control panel gave up the ghost and the local chap was out of salvaged spares... so I replaced the control panel with two zigbee relays (hot water and heating). The automation looks at the zigbee TRVs and sees if any of them are calling for heat. If so, boiler pops on. Having something genuinely smart mediating the call for heat from TRVs to the boiler demonstrates how trivial the control model is.
I guess Honeywell Evohome does this but most of the others didn't when I last looked. Price tag on Evohome is daunting. I'm not going to pretend that the entry cost and learning curve for setting up a full smart home setup is nil, so my distinctly niche solution only made sense because from my POV I just had marginal costs (TRVs from AliExpress; relays from Amazon).
(disclaimers: not a gas boiler so no gas-safe regs breached; non-TRV radiator on the circuit so flow is always possible).
I'm certainly not going to dispute any of the above.... but you've moved to a smaller house and your heating requirements have gone down
😀
(19% smaller floorspace but similar cubic volume to heat due to high ceilings downstairs 😉)
We expected any size-related reduction in gas usage to be wiped out (and more...) by the move from new/efficient to very old/inefficient house. If it'd been like-for-like newbuild to newbuild fair enough, but surprised in a good way at how our leaky old non-insulated house performs.
I did think about it years ago (and the Honeywell system as that seemed to be the best at the time) but just couldn't really justify the cost.
Can't put a price on avoiding grief from my wife/daughters who don't know how to handle the cold 😀
But quick search suggests the components for our set up (controller plus 8 TRVs) is now £700 - we were a bit less 8 years ago - plus any install costs. Can't find what we paid our plumber to wire the receiver bit to the boiler, we fitted the TRVs to the rads ourselves.
I guess Honeywell Evohome does this but most of the others didn't when I last looked.
My Tado system does this, but also not cheap.
My feeling is that if the boiler is running for one room* then you may as well heat all of them (within reason).
Yeah, when I installed my Tado system to give me per room control years ago, I have to admit I naively though being able to heat individual rooms would save me loads of money. It turns out that that is unlikely - when you fire up the boiler you want to take advantage in as many rooms as possible. The bigger the temp drop between the hot water exiting the boiler and it returning, the more efficiently the system is.
Having said that, I still think the Tado system saves me money purely on how much better a geolocation based system is compared to a dumb timer - why heat the house if you are not in it - or are you really adjusting things manually every time you leave the house? I believe there are 'Smart' systems that still don't implement this well, or at all, which blows my mind.
My current controller does Hot water and heating, do these receivers replace the current controller?
My wireless thermostat receiver is wired into the pre-existing external controller (I have an old super-dumb oil boiler) - do smart systems even control hot water production?
I'm certainly not going to dispute any of the above.... but you've moved to a smaller house and your heating requirements have gone down 😉
I can see that not heating upstairs until later in the day is beneficial but that could be achieved with a circuit for upstairs and another for downstairs.
There is also the unresolved argument that heating should be on all the time. Who knows!
I did think about it years ago (and the Honeywell system as that seemed to be the best at the time) but just couldn't really justify the cost. I may have been wrong, but now that my three girls have left home I just turn the TRVs down in their rooms when they're not around.
My feeling is that if the boiler is running for one room* then you may as well heat all of them (within reason).
* I can't get my head around the idea that a single room calling for heat entails firing up the boiler!
I fitted a Tado "smart" set up which has Combi Boiler control and Tado TRV's on all 7 radiators in December '24. Being able to control when each room gets hot vs heating the whole house has allowed me to reduce my overall gas usage, Nov'24 vs Nov'25 was 210 kWh less, Dec '24 vs Dec '25 was a draw, however we were home more this December in the day due to lurgy and had the heating on more.
I'm expecting the gas usage to reduce 15%-20% and pay for itself over a couple of years, my OG Ideal Halo Thermostat had died and I was being priced £200 to get the latest one from Ideal, think I paid £350 for all the Tado stuff around black friday-ish.
I do like the Tado set up with some very minor grumbles, I like the geo fencing, it pops up each month and I recall in Nov and Dec it was around a 100 hours of heating saved each month using Geo Fencing.
The system also does some stuff with Opentherm which the last controller didnt and is meant to save on Gas, there is also a Flow Temp Optimisation which I can see has lowered the boiler set value of 65degrees to 58 degrees which I guess also saves Gas
One of the deciding factors for this system was WFH, I used to use a small electric heater which was nosey, pricey and quite rubbish or heat the whole house, this Tado set up allows me to heat the one room only and like for like costs less too and isn't nosey so I can be on calls and hear people!
just to chime in with ive installed a tapo (similar) recently and it can do what you are after. Theres also an offer via octopus that may help?
Nov'24 vs Nov'25 was 210 kWh less, Dec '24 vs Dec '25 was a draw, however we were home more this December in the day due to lurgy and had the heating on more.
I'm not doubting your numbers but don't forget that November '24 could have been warmer overall than Nov '25 which would reduce the amount of heat required.
There are a number of variables so it's pretty hard to pin any reduction on just one thing.
Geofencing: agreed
Lowered the boiler set value: agreed but couldn't you have jut done this yourself?
Small electric heater which was nosey: an electric oil rad is silent
This Tado set up allows me to heat the one room only: This I struggle to comprehend - running a boiler big enough to heat the entire house (and pumping water all round the house) simply to heat one room 🤯
But if you needed a new something anyway and you're happy with it then that's good 👍
REading with interest for my mums house. She is there by herself so could help her manage better.
running a boiler big enough to heat the entire house (and pumping water all round the house) simply to heat one room
I think I understand this in that yes, hot water will be going around the system pipes but not into all radiators so the temp drop from boiler output to boiler return will not be as great so the boiler runs for less time... or have I got it wrong?
No you're probably right.... But it still seems bonkers even though it may not be.
I think I'm just very wary of "new" tech that is supposed to make life better, but in fact the only people it makes life better for are those selling the tech!
IME the best way to run these systems is to have all radiators with smart TRV's.
How do you deal with the radiator on a circuit that is 'permanently open', so should not have a TRV fitted?
At least one radiator should be open to prevent boiler flow stopping, for us it's a towel radiator.
At least one radiator should be open to prevent boiler flow stopping, for us it's a towel radiator.
You can have a bypass valve installed as an alternative.
At least one radiator should be open to prevent boiler flow stopping, for us it's a towel radiator.
Is this for all heating set ups? I just changed all my TRVs to Tado ones.
we were recently told by our service engineer that the one 'open' radiator was a relic of old boilers and new combi designs (say <3yrs, like ours) don't need them.
someone further up said that return temp should be significantly different to heat temp for the boiler to be efficient. I always thought it was the other way round, and that smart RV's not only puts heat where you want it, it means that return temp is higher due to not losing heat through lots of radiators so the boiler doesn't have to heat so much, thereby reducing fuel consumption?
we were recently told by our service engineer that the one 'open' radiator was a relic of old boilers and new combi designs (say <3yrs, like ours) don't need them.
Could well be true, but both my heating circuits have towel rails without TVRs in them.
someone further up said that return temp should be significantly different to heat temp for the boiler to be efficient. I always thought it was the other way round, and that smart RV's not only puts heat where you want it, it means that return temp is higher due to not losing heat through lots of radiators so the boiler doesn't have to heat so much, thereby reducing fuel consumption?
That would be me, and was half remembered! Having very quickly checked, it's not the drop in temp as such, but the water returning should be at 54 deg or below for your boiler to be operating in condensing mode, which is a bazillion time more efficient. This can be achieved by either setting your water temp lower, the water dropping in temp as it cruises round round your house (much more likely if it is going through lots of rads rather than just a couple) or both. If your flue is belching out steam all the time then it's not running in much more efficient condensing mode.
https://www.theheatinghub.co.uk/why-our-condensing-boilers-do-not-condense
I think the OP’s confusion should now be resolved by the thread. But at the risk of repetition, adding smart TRVs that have no boiler control (receiver) to turn the boiler up or down or on or off is just like having regular TRVs: you’ll get radiator control but add no other benefit. To make ‘proper’ use of a smart TRV you need a receiver that can control the boiler and heating circuit activity.
This could be an on/off receiver-controller to replace the current wired thermostat, or something more local to the boiler. Keeping the existing wired hallway thermostat could negate some of the ‘smart’ TRV benefits as it may create upstairs demand when none of the TRVs are asking for any heat if it is set to a higher temp.
In a statement that will surprise no one, room temperature has a floor to ceiling gradient in a draft free room. https://protonsforbreakfast.wordpress.com/2026/01/06/variation-in-room-temperature-with-height/
Running a condensing boiler at lower temperatures tends to increase efficiency. As was said, a return temp of <=55°C is needed. Running our condensing system boiler at 50°C for heating over the last few years has been sufficient. https://www.viessmann.co.uk/en/heating-advice/boilers/what-temperature-to-set-condensing-boiler.html#What%20is%20the%20best%20temperature%20for%20a%20condensing%20boiler?
We have a Hive controller. Aside from the Hive account no longer working and the hub therefore being fairly useless this has been an OK setup. 1 room thermostat that is wireless and is in a commonly used but cool room and ‘dumb’ TRVs elsewhere to limit heating to appropriate levels in other rooms. We have a bypass valve in the system for if all TRVs close. I’ll not complicate this picture by adding in the way our UFH system integrates.
I can see smart TRVs being handy if you want individual room heating control.
To make ‘proper’ use of a smart TRV you need a receiver that can control the boiler and heating circuit activity.
SNIP
Running a condensing boiler at lower temperatures tends to increase efficiency. As was said, a return temp of <=55°C is needed. Running our condensing system boiler at 50°C for heating over the last few years has been sufficient.
I would also add that I fitted an outside temperature sensor to my last boiler. It made a huge difference as the boiler ran at different return flow temperatures depending on outside temperature. The dial to 'turn up' the heat flow actually increase the 'heat slope' in that graph. If you came into the house on a freezing day the radiators felt hot. On a cool day they were tepid.
I had a plumber refuse to fit it, claimed it was not worthwhile. The sensor cost £30 iirc and took under an hour to fit. Saved about 10% / £120 annually off my gas bill...