Experiences with smart thermostats / TRVs

Hi all,

I’ve got a plumber coming soon to install a smart thermostat. He’s recommended Nest.

I’ve been reading on posts here and some have suggested having smart TRVs which through HA can simply turn on or off the boiler (via a switch or something).

I have a regular (not combi, 2 yr old) boiler with a hot water tank, so need the thermostat to control the hot water too. Not sure if there’s anything that can be done in HA with this? I’m happy to leave that up to the thermostat though I think.

As I’m in the research stage, can anyone please share their set ups on this? I have around 8 rads. I’m also wondering do people run the heat based on average temp across all TRVs or would you switch the boiler on to just heat one room which drops below the desired temp?

Thanks in advance!

I don’t have a boiler, but I made generic thermostats of each TRV where I use an external temp sensor.
It works great for us, the only problem I have is the TRVs have a schedule that I can’t remove.

No experience with TRVS. I do have a hot water heating system with three zones plus hot water tank. I have a NEST, 2 zwave thermostats, a relay, and a CT sensor.

NEST - the nest build is good, it is a cloud based solution, so if you lose internet connectivity you lose the ability to monitor and control. Currently I’m working on bugs in the integration, as when it loses connectivity the integration reports stale data forever. NEST drops about 2% of the setpoints, so if your doing automated setpoints you’ll need to check and verify. The plus is there’s a nice app that can be easily used to control remotely and it has a proximity sensor to turn on its display when you walk by.

Zwave Thermostats - Honeywell. These work locally with zwave. There are a couple of automations needed to refresh data periodically. They have been reliable and don’t suffer from the stale data problems that NEST has. They drop maybe 0.1% of the setpoints, so again a retry mechanism is needed.

Relay - I put s low voltage relay in series with the hot water thermostat 24vac loop, this allows me to turn off hot water when away and then turn it back on before I get back.

Current Sensor - I put a current sensor on the AC for the furnace. This allow me to know when the furnace is actively running and calculate oil use (it has a 0.8gph nozzle). Also put s CT sensor on the hot water thermostat loop, to know when HW is in demand.

With this instrumentation I can calculate overall oil usage and per zone oil usage.

A way to get better efficiency is to have the furnace run longer and less often. What I noticed is zone 1 would come on, 10 minute later zone 2, then zone 3… So I implemented a zone coordinator to get zones to come on together, Basically, when a zone comes on, I’ll boost the temperature by 1 degree on the other zones (subject to some rules), when that leading zone turns off, the boost is removed. I now have all my zones coordinated.

No experience with TRVS. Since you’ll be doing control (whereas in my system the thermostat does the actual control), you’ll need to have it be reliable and consider what happens if the temperature sensor stops reporting, HA crashes, etc.

Happy to post code for any of the items above including sensor health, thsr you want.

That is not what a TRV is as a “TRV” are just a “Thermostatic Radiator Valve” which controls flow control for individual radiators in a hot-water heating-system where that TRV is located (“Radiator Valve” being the keywords as each radiator needs its own TRV as they all have their own valve), so they are only used for controlling the temperature in a single room instead of the whole house. So a TRV is not a device that controls your boiler directly, instead, they only control the physical valve located on each radiator which means that they need to be installed directly on the radiators themselves.

Wikipedia article on TRV → https://en.wikipedia.org/wiki/Thermostatic_radiator_valve


Wikipedia article on Thermostat → https://en.wikipedia.org/wiki/Thermostat

I recommend combining a smart house thermostat (such as for example the Nest Thermostat) with many TRVs which are installed on each individual radiator in your house, as that way you get the best of both worlds with a smart house thermostat which controls the general temperature in your whole house and then each TRV control the temperature in just the room it is in. That way you can have a hotter or colder temperature set on individual radiators located in different rooms like for example hallways, bedrooms, home office, and launch-room. Note though that in such a house thermostat + multiple TRV combination setup the main smart house thermostat (such as for example the Nest Thermostat for the central heating system + some kind of TVRs for all radiators) does not know anything about the TRVs or vice versa, so there is no communication between them whatsoever, but they still compliment each other anyway.

Personally, I am currently combining a cloud-based smart thermostat for the whole house t(Ngenic Tune) and a total of 15 individual TVRs (Eurotronic Spirit Z-Wave Plus) that I have installed on the valve of each individual radiator in our home in order to control the temperature in each room separately as well as set a general temperature in the house.

For a TVR example that used Zigbee see example these:

Aqara Radiator Thermostat E1 → https://www.aqara.com/eu/product/radiator-thermostat-e1

Moes ZigBee TRV (BRT-100-TRV) is another → Using Moes ZigBee TRV (BRT-100-TRV) in my old heating system - NotEnoughTech

An alternative to a Nest Thermostat is a Zigbee thermostat like example this → A budget ZigBee thermostat? - NotEnoughTech

If you instead want all-in-one smart solution (usually meaning cloud-based) that is not a DIY setup then Zigbee is probably not for you, and instead, check out other non-Zigbee solutions such as Tado or Netatmo which also have both TRVs as well as smart house thermostats.

Check out this discussion posted on the blog which specifically brings up TRV as a concept and mentions some specific products → Short-term solutions on how to use smart home tech to save energy and money in Europe - Home Assistant

Here is btw a whole list of ZHA / Zigbee compatible TRV (Thermostatic Radiator Valve) models and Zigbee thermostats → https://github.com/zigpy/zigpy/discussions/653#discussioncomment-314395

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The sponsored channel made a review of Nest TRV’s that can control the boiler also.

Install This On Your Radiator

No. That just shows a TVR from Tado which is installed on the valve of an individual radiator in a single room (and not a Nest branded TVR product from Google), and even if it was, being a TRV it would by definition not be controlling your boiler (water heating / water heater) for your central heating system.



Nest Thermostat (any generation of Google Nest Learning Thermostats) is a product that does control your boiler directly, so do not confuse those two as again, TRV does not control your boiler directly.

Read → https://support.google.com/googlenest/answer/9259740

How radiator valves work with Nest thermostats

Google Nest thermostats, namely Nest Learning Thermostat (all generations) and Nest Thermostat E, work alongside your existing radiator valves to help you stay comfortable and save energy. Nest thermostats are compatible with various radiator valve types, including Smart thermostatic radiator valves (Smart TRVs).

Your Nest thermostat controls whether the hot water flows to your radiator, and your radiator valve controls the pressure. Once you adjust your radiator valves to your preference, you can use your Nest thermostat to control the temperature so you don’t have to adjust your valves often. Note that when your radiator valve is closed, hot water doesn’t flow through your radiator.

## Radiator valve basics

Radiator valves reduce or increase the amount of hot water that enters the radiator. Radiator valves don’t turn the boiler on or off.

When you turn your thermostat up, your boiler provides hot water to the radiators in your home. Since each room in your home heats up differently, radiator valves are used to fine-tune the temperature of each radiator. Nest thermostats and radiator valves work together. The thermostat heats your home to the temperature you like, and the valves balance each room individually.

When you set up your heating system, adjust your radiator valves properly to help tune your home for even heating and save energy in rooms that are rarely used. When your Nest thermostat is first installed, make sure that your radiator valves are tuned the way you like them.

There are 4 main types of radiator valves:

** Manual radiator valves*
** Thermostatic radiator valves (TRVs)*
** Electronic programmable radiator valves*
** Smart thermostatic radiator valves (Smart TRVs)*

## Tune the valves during installation

When you install your Nest thermostat, it’s recommended that you or a professional sets the valves in each room for even heating. Most manufacturers have recommended settings which you can use as a guide. You can also try different settings to find out what’s right for you.

1. Set your Nest thermostat to a comfortable temperature on a cold day. Check which rooms are too cold or warm. Turn the radiator valves up or down, as needed. You may need to wait a few hours for the temperature to stabilize.
2. If some rooms are still too cold and the valves are open all the way, turn the thermostat up. Turn the valves down in warmer rooms to even out heating between different rooms.
3. Make sure the valve on the radiator closest to the Nest thermostat is open. If it’s closed, your thermostat can’t sense the temperature change and your boiler might run inefficiently.
4. To save energy, turn radiator valves down in rooms that are rarely used, like guest rooms or storage rooms.

## Manual radiator valve|autoxauto Manual radiator valves

Manual valves work the same way as a water spigot. To allow hot water to enter your radiator, turn the valve.

If you have manual valves, make sure the valves are open for each radiator so that the radiators get warm when your Nest thermostat heats. You can also close valves that are in rooms you don’t use very often, like spare bedrooms, so that your Nest thermostat doesn’t heat empty rooms.

## Thermostatic radiator valve|autoxauto Thermostatic radiator valves (TRVs)

Thermostatic radiator valves (TRVs) control the amount of water that enters a radiator. Unlike a manual valve, a TRV can regulate the temperature with a range instead of just on or off. The range is usually set between 1 to 7.

If you have TRVs, make sure to set them so that your home heats evenly. You can also turn the TRVs down to a lower value in rooms that aren’t used often so that you don’t waste energy heating an empty room.

## electronic programmable radiator valve|autoxauto Electronic programmable radiator valves

Electronic programmable radiator valves can be programmed from a central hub to heat to a specific temperature at different times of day.

It’s usually easiest to set programmable radiator valves to one value that provides even heat throughout your home. To adjust the heating, use a Nest thermostat’s schedule instead of the radiator valves’ schedule.

When you use the radiator valves’ schedule to turn down the temperature while you’re away, you save less energy than when you turn down the temperature on your Nest thermostat.

## Smart thermostatic radiator valves (Smart TRVs)

Smart thermostatic radiator valves (Smart TRVs) are also compatible with Nest thermostats. When your Nest thermostat turns the hot water on or off, the water flows in compliance with the Smart TRVs’ settings.
How radiator valves work with Nest thermostats - Google Nest Help

True… I wrote from my poor memory.

a bit confused. I am like many other people want to save money and purchase the ideal solution for they home.

I have just purchase and installed a Nest Gen 3 Thermostat to heat my Radiators, and I am looking at a smart radiator values to control the flow through my radiators, as I understand that the radiator can’t control the Nest directly, which is why I am looking at using Home Assistant to manage that side of this. and create zones within my house and have schedule heating of zones.

the area I am confused about is getting the right smart radiator value, as I don’t want to spend a lot of money on them, and I want them to connect to the current ZigBee network, and not have a second Hub just for them.

any suggests ?

also does anyone know of a good source of information that will help me to create my automation / scripts for the control of my heating.

You left out the most important part.
What ZigBee controller do you have, what integration are you using?

My recommendation is to get TRV that is as dumb as possible but still controllable.
There doesn’t need to be any logic at all in the TRV, no schedules are needed, nothing really. As long as you can send the commands from HA then you put all the “brains” in there.

sorry I have a DeCONZ i/II dongle Controller - that and if I am reading you right, the integration will be ZigBee

TRV that is as dumb as possible

what type of dump TRV would u look at ?

I saw someone else mention it, and it’s nothing that I knew existed.
But a radiator valve that just did want it was told to do.
Can’t remember the name of such device.

Now I do… radiator actuator.
I just searched for them when it was mentioned and most seem wired, perhaps there are wireless versions.

I didn’t invest more time in it since I already have TRVs in all rooms.
I bought my TRVs very cheap, but had they been more expensive I might have thought about replacing them and sold my existing.

This is a very well documented scenario, with one important assumption - that you’re in control of both your radiators (and therefore you have the option to install xTRVs) and your boiler.
In my case, actually in the city where I live, by Central Heating we understand city-wide heating. The utility company flips on their ‘super-Nest’ sometimes late Octoberish and keeps it on till late March/April whatever. Plus there are local (per building) ‘sub-statitons’ that regulate hot water flow based on i.e. local thermo sensors and building size and probably other stuff.
So as a condo resident all I’m left with are the TRVs at the radiators themselves and to a huge extend they do a pretty good job of managing the temperature.
This year I’ve invested in Smart TRVs (Zigbee based), not to save additional energy (I doubt this can be done easily in my particular setup) but to automate stuff I’m now doing manually - i.e. turn down the temperature when there’s nobody home, bring it back up just before we’re back, sync with door/window sensors, etc.
Plus the ability to use a temp sensor that can be positioned where I need it, not glued to the radiator and therefore potentially more representatives of the ‘feels like’ temperature in the room.
Oh and by the way, having multiple sTRVs allows you to create an i.e. Generic Thermostat in HA and use them all at once - obsoleting the need for a Google Nest or whatever.

I have the same setup, if you really did all that work manually then hats off for you.
Most people set the radiators on and then only adjust when desperately needed and don’t turn them of when going to work etc.

Since we have access to the individual radiators usage and the average of all condos in the house I can say you get a big difference with TRVs.

The graph of usage shows that when we installed ours we went from being one of the biggest consumers in the house (since we have the largest apartment) to be below average.
This change happened from one week to the next (or possibly one more week).

But we did not do all that work manually of turning the radiators off every day when we leave home or when we open a window.

Ciao ho acquistato delle valvole termostatiche Tuya anche io, le TV02, le ho integrate in 2Mqtt e fino a qui tutto ok…premetto che ho fatto il tuo stesso ragionamento prima dell’acquisto, ottimizzare la spesa nelle bollette e dato che durante il giorno non c’è’ nessuno a casa accendendole quando voglio è un bel risparmio.
Quello che ti chiederei è: come potrei gestirle al meglio creando un’automazione con accensione e spegnimento al mattino e accensione pomeridiana con spegnimento serale?
Avresti voglia di darmi una mano?
Grazie in anticipo.

around a month ago I installed 14 TRVs - the new SONOFF ones at the launch price. I set up a calendar for the heating and a simple automation to turn on / off the TRVs at the start / end time of the calendar entry for that room. This is working well and will get more smarts - absence detection - in due course.

At the moment, the boiler is controlled by a simple digital timer with up to three periods per day - it’s hard to read and awkward to program.

I’m looking for some advice - do I set the boiler to continuous and rely on the TRVs or should I look for a boiler stat that connects to HA?

If I do have a smart boiler stat how does that look in HA - each room effectively will have central control and local control - both need to be active to heat up…?

Do not set the boiler to run heating continuously if all radiator valves are closed. The boiler will continuously cycle the burner on and off with only the water in the pipes being heated, this may damage your boiler. You need a programmable thermostat. If you want to DIY it then you could use a simple smart switch/relay connected to short out the thermostat wiring terminals in the boiler (which is effectively what a wired ‘click’ type room thermostat does), this can be switched on via an automation every time one of the valves calls for heat.

I was concerned about this, but found that the majority of boilers made in the past decade handle this condition and will stop the central heating pump automatically when all radiator valves are closed.

Hi Steve,

I have a similar setup, in my case I found that the boiler automatically shuts off and stops providing heat when all the valves are closed, but doesn’t start up again unless you physically press some buttons.
I use Popp TRV’s, which report the valve state, and I added an automation that opens one of the living room thermostats if the added valve position is below a certain number, which is typically the case when none of the rooms needs heat and the boiler is off. In my case I have a programmable thermostat to do the central control of the boiler but in the past I’ve used a relay controlled from a Raspberry Pi with GPIO and also a Zigbee relay to control the boiler. You can make an automation that reads the setpoint and current temperature and shuts the boiler off when there is no demand for heat, this will save energy.

My boiler’s programmer is starting to have issues, so I will need to replace it when we move from winter to spring (24h on to timed on / off periods).

So far I have not been able to find something suitable.

I want it to have some level of Smart Control - i.e. reporting the central heating is on or off, and perhaps controlling the timer. What I keep finding are thermostats, but my boiler is in a small utility room where a thermostat will not read a useful room temperature. All the rest of the house has the SONOFF TRVs reporting their state using ZHA.

Can some of the smart TRV’s like hive be set to ignore the room temp and just program the on / off schedule?