You’re absolutely right! I should have known having changed enough of them in the past.
@Confused - The radiator valve works perfectly -= and is super quiet too.
How did you get on?
I’ll more than likely be ordering 4 more for the other radiators - haven’t decided what approach to take for the power feed - currently am just hanging off a lightwaverf power socket - but sonoff seems nice and cheap.
Mine was delivered today, so still getting it set up with OH - will hopefully have a bit more of a play tonight.
Game plan is a simple xiaomi temperature measurement in each room and an On
/ Off switch for the Thermostat via sonoff or similar.
I’ll create a Single switch that governs whether any heating is required.
Each zone will have operating hours and desired temperatures (for this
hours only)
Each zone has a further switch to determine if THAT zone needs heating.
I suspect I’ll then have modes
The requirement for each zone will be determined as follows:
If (away){allzones = Off}
(I have nest, so can use the home/away functionality of this to dictate
status accurately)
If (home){
If (temp < desired temp && now > zonestarttime && now < zoneendtime) {set
zoneswitch = On}else{set zoneswitch off}
And then finally a wrapper that triggers if any zoneswitch changes and
simply says
If (any zoneswitch = On){masterswitch = On}else{masterswitch = off}
I’d need such a rule for each zone - and would either need to fire the the
evaluation every x minutes, or whenever a new temperature is received.
Xiaomi temps are reported when more than 0.5 degrees of change have been
detected, or about 50 minutes have passed.
I’ve not found any sample rulesets on the community, but this shouldn’t be
too tricky to code, just arduous.
If you code something up before me please share
Hi Garry,
I saw you ended up with knockoff Sonoff’s 
I am getting some LightwaveRf switches in the post today - a;lready have everything else, so will be good to go using these.
I also have an original Sonoff - but don;t have the USB adapter to flash the firmware (actually . . I should dig in all my old Arduino stuff . . maybe I have one)
Irrespective, when I get that, I’ll give you the rundown.
That said though, the price increase from Sonoff to LWRF is only about £5 a unit - not sure I want to be flashing things and getting all “hardware-guy” to save so little.
In a time where I was building controllers usding Arduino . . I learnt just how bad I am at soldering and how timeconsuming hardware mods are.
Let me know how you get on.
You actually don’t need to solder anything, or use a USB adapter, you can update the firmware to Tasmota over-the-air which takes only a few minutes to set up initially, then about 2 minutes per device.
I’ve now actually got 4 rooms under temperature control, and they’re working very nicely!
I’ll do a proper write-up of it soon, but the basics are the Thermal Acutator, and the Sonoff, and controlling my Nest (which I’ve disabled all the smart/learning stuff on, and am simply using it like an On/Off switch)
Only a temporary installation at the moment - when I move I will be doing it much more nicely, running cables through the floor etc.
With my setup, each room or zone can have 1 or more temperature sensors, which it will average out, and then use those to determine whether to switch those rooms on or off.
I am using an ESP8266 and DHT22 - my plan is to add a rotary encoder, PIR and OLED display to each one, and have this be used for displaying current temperature, setting the new temperature, and used for other purposes - controlling music, displaying weather information etc.
Like I said, I’ll do a proper write-up soon of it 
2 Likes
Garry,
That’s awesome.
I have almost an identical setup.
I’ll try find the Tasmota OTA firmware update guide.
Do you mind sharing your rules?
I have inbound temperatures off Xiaomi Temp sensors up and running,
Upstairs is on its own Nest circuit (which will be changed to a dumb device like yours)
I won’t bother with the rotary / digital displays. I am simply presenting the data in habpanel – so can provide each room tenant their own page and they can control / read temps on their smartphone.
Looks absolutely perfect!
Yep I’ll share all my rules etc - just need to sort out how I deal with “Away” mode with the Nest, which I’ll hopefully get sorted over the next few days 
I have 2 nests - have a few rules tied into away mode already. What probs have you got?
Managed to set up an mqtt/sonoff - flashed ota with Tasmoto. I like it!!
Hi all, very new to this, I’ve been thinking about this for a while, looking for a cheap solution, was looking at this thread and have a question.
If you need to run power to the trv, why use the sonoff, couldn’t you just go back to a relay board?
Sonoff is just a cheap relay with some clever firmware onboard
Guys, thanks for all the posts above, just been fighting with TRV’s and would rather cook my own solution!
@Confused - Could you do your writeup - avid Sonoff user here!
Also does anyone know of any PWM models so one can reduce the flow instead of On/Off - Have a nodemcu unit that i have almost fully working to control PWM gating so if someone finds a PWM model !
Any links to what models of actuators you are using - please do post, all the ones above are unavailable.
Thanks !
James
James - I use on / off via a Sonoff and a £12 trv - I switch on when temps are 0.5 below target and off when temps reach target.
My one room cycles once per night, the other, three times - but it’s more than sufficient - wouldn’t bother trying to be any more granular
Cool, which trv are you using ?
I have been looking for some mains powered ones - threr are lots - not sure which to trust (have 14 rads to wire up!)
£12 that’s very cheap
FWIW I have 1x Devolo (Was my first TRV) which is really good at keeping temp (The variation is very small) but was an absolute PITA to get included and installed. Like hours and lots of cursing. It also feels a little less physically robust than I feel it should. It does report back temp, so not a complete
I also have about 4x Eurotronics Spiritz TRV’s. They feel better built. Way easier to access the battery compartment, the display is clearer, controls are better. It also reports back temp. And was way easier to include.
I really like this idea. Looks cheap, reliable, platform independent and easy to realise.
I think Confused/Garry Mitchell’s idea of DIY modulation is really cool. From what I understood the valve is controlled by a wax expanding/shrinking depending on whether power is On or Off, taking approximately 3 minutes in total to go from fully expanded to fully shrunken. The time it takes also depends on ambient temperature it seems. Mind you, it’s close to the valve, so it the ambient temperature there might range from 15C to 50C/85*C, depending on max supply temperature of your boiler, heating on or off, and heating duration. This might really be of influence. But you could imagine something like this.
Mode 0: Sonoff Off
Mode1: Sonoff alternating 45s On, 135s Off (alternating for as long as valve should be open)
Mode 2: Sonoff alternating 90s On, 90s Off (alternating for as long as valve should be open)
Mode 2: Sonoff alternating 135s On, 45s Off (alternating for as long as valve should be open)
Mode 4: Sonoff On
Not sure if it works. And not sure if the Sonoff and the Actuator will like the alternating treatment, but it could be a solution… The lower your boiler supply temperature, the less you will likely need this modulation option.
Numbers above all based on 3 minutes to go from fully open to fully closed. You can check how long it really takes for your actuator by just turning it on without it being mounted, and just see how long it takes to fully expand/shrink. Once in the middle of the room (+/- 20C) and once while placing it on a tea towel or something on top of the radiator fully opened (>50C)
@Confused Thank you very much for sharing! Some questions though: Do you know what’s the Central Heating (maximum) supply temperature in the case of this image: https://community-openhab-org.s3-eu-central-1.amazonaws.com/optimized/2X/6/63e6046d59119e302a2f472c6446dc5bf70963a4_1_690x362.png
The fluctuation of 1*C are quite large…
And what’s the latest news? Still happy with your setup? Did you tweak it?
@dabachata The Operation you described above is common in professional room temperature control. I have a LCN System installed (from German firm Issendorf) which uses 230V (AC) thermo-electric control for radiator control and under-floor heating valves (called LCN-AVN). These valves are controlled by the control module, which could be parameterized to a mode called “PPS” (german: Puls-Paket-Steuerung / engl: pulsed packet control). this mode is an adaption from PWM for AC voltage. You specify a time frame (less than the maximum open/close time of the valve) and the control calculates the on- and off-time of the output for the valve.
For your example it is
Mode 0: 0%
Mode 1: 25%
Mode 2: 50%
Mode 3: 75%
Mode 4: 100%
The LCN system calculates the on-/off-time via a regulator with a resolution of 2% or 0,5% (dependend of the module)…
1 Like
Hi,
I have used exactly the same solution. Thermal actuator normal closed and Sonoff.
I control 6 radiators around the house with mysensors temperatures and humidity sensors in each room.
I control the target temperatures and times with node-red and the ramp thermostat node.
I have all the different profiles for each room in a json file the node-red read and applies the profile to the node according to the day of the week and/or house mode (AWAY, HOLIDAY…)
Very reliable and I have touched any of the devices for months.
Regards
1 Like
@vzorglub You use simply On/Off and not the above mentioned “Puls Paket Steuerung” / “Puls Packet Control”?
Sounds like you have City/District Heating, right?
Do you know what the heating water supply temperature is? (The temperature of the water before entering the radiator.)
I’m very interested to know the temperature fluctuation you experience with this setup. So say your target temperature is 19.C, how much does is fluctuate around 19.C once the temperature in the room is already near target (e.g. target 19.C, range 18.6C-19.7C) Depends also on the temperature of the heating water flowing through your radiator, so that would be great to know too.