In my quest to optimise home heating, I’ve been trying to find the perfect smart thermostatic radiator valve (TRV) that meets my needs. There’s plenty of different systems out there, however they all have their advantages and pitfalls. Here’s what I’ve tried so far: TUYA smart TRVs, Tado Smart Radiator Thermostat, Hive Smart Radiator Valves, Shelly Wifi TRVs and finally the Drayton Wiser Smart TRV.

My view of perfect:

• Good battery life (6 months minimum)
• Aesthetically inoffensive
• Work locally without specific app, or internet connection, as I’m already married and don’t need another commitment
• Good support in HomeAssistant
• Able to act ‘dumb’ and be told to open or close fully, or set valve position

I’ve chosen to use Zigbee2MQTT to integrate. I’m aware there are other options which have their pros and cons, but right now I’m sticking with this. My Controller of choice is a Zig-a-zig-ah from Electrolama, after having not much luck with a Sonoff bridge due to less than stellar support within ZB2MQTT/HomeAssistant, even when flashed with Tasmota.

Tuya Smart TRV

Tuya isn’t a brand but rather a cloud platform supporting IoT development and services. There’s all sorts of devices supported, from curtain tracks (which we have, and work magnificently) through to smart heating, such as the Thermostatic Radiator Valves. It’s well supported in HomeAssistant, either through the Tuya integration (which requires setting up a developer account and a few manual hoops to jump through) or through Zigbee2MQTT. There is an integration called TuyaLocal, available through HACS, however it only supports devices: Zigbee devices are subdevices of the gateway, and hence are not supported as of 3.4.

I bought mine from AliExpress, and it arrived quickly along with a Zigbee gateway. After validating it worked, I bought another 4. Shipping took a week or two, but was cheap and efficient.

To prove they worked, I used the Tuya smart app (available on iOS or Android), which supports setting schedules and temperatures, boost, lock outs etc. It’s well featured, but does require connectivity, and privacy questions may remain for you. I’ve since changed them so they are paired with my main Zigbee network connecting to the ZZH stick, and they’re fully under the control of HomeAssistant via Zigbee2MQTT.

Physical controls are present, and are accessed through the ‘waffle’ button in the middle and the +/- at the top. They’re quite frustrating to use. Annoyingly, when you change batteries you need to set the time (or confirm the time if it’s already connected to the network) by pushing buttons multiple times.

Controls surfaced are plenty: target temperature, operation mode (auto, heat, off), preset mode (none, schedule, manual, boost, complex, comfort, eco), auto lock, away mode, child lock, valve operation mode (force open, force close, normal), valve detection, and open window detection mode. Sensors are temperature, current valve position, Window open, Force mode and week day, and configuration items include: away preset day count, away preset temperature, boost time, comfort temperature, eco temperature, max temperature, min temperature, and local temperature calibration, which gives you the option to provide an offset to the sensed temperature at the valve head.

I always use rechargeable batteries, and the Ikea LADDA 2450mAh batteries are cheap and good – however, within days the valves would warn of low battery, and I would need to recharge every two weeks or so as the valves would turn off. Rechargeables only provide 1.2v as opposed to 1.5v, and these valves are not happy at this level. You can either use normal batteries, or rechargeable Lithium batteries which do provide 1.5v – I have had success with the Kratax brand.

One valve has failed, and no longer works as it fails calibration. The motor is dead: I’ve stripped it down, and the motor is simply unresponsive. I could try to replace it, but that would be throwing money away as the motors are not particularly cheap. Other motors are definitely slowing down and sound laboured in their operations so I do question their reliability. There do seem to be other models available now, however I have not tried them. I have found that the valve it was installed on had become stuck, so it may have burnt the motor out trying to move this. There is no option to open/close valves periodically automatically: this could be configured within HomeAssistant. I’m going to look into doing this every week or so to try to prevent valves sticking and potentially damaging smart TRVs.

In conclusion, a well supported valve, with local integration options via Zigbee, with a plethora of controls and configuration. I do question the reliability but there is a mitigating factor.

tado

Tado does look neat, however it uses its own network technology that has its own gateway. It’s not Zigbee, and it’s a different frequency so simply isn’t going to work. There is an integration with Tado’s cloud service, or alternatively you can integrate with HomeKit which uses local calls to the gateway.

Physically, this is small and elegant, and the interface is simple: simply turn the top to change the temperature, that’s it. It does work well, The display illuminates when you interact with it.

Through HomeKit integration, it exposes a single control, target temperature, and 2 sensors: temperature, and humidity. The humidity in particular seems inaccurate, being 15% different from a Sonoff temperature/humidity sensor. There is no inbuilt temperature correction offset, or demand signal, valve position etc. Compared to others, it does not give much flexibility, but you can set the temperature. There’s no valve control at all.

Power is again 2AA batteries, and these seem to have lasted over a year. Rechargeables are supported.

Due to its requirement for yet another interface, and lack of exposed controls, I would not recommend these for integration via HomeKit with Home Assistant, and will be replacing mine with a Drayton Wiser Smart TRV.

Hive

Hive is a rebranded Danfoss device, supported in Zigbee2MQTT. Again, I bought 1 to see how well they’d work, then bought another 3 on ebay as a bundle. One of those was completely dead, again the motor had died so it would not pass calibration. As it was second hand I do not know how old this was, or what had caused the problem. Like the Tuya, the motor was completely unresponsive.

The physical interface is fairly good: there’s a button to wake that also serves as a pairing button, and you can set temperature by twisting the whole of the top. It’s a little clunky but better than the Tuya. The display illuminates when you interact with the device.

Of all the TRVs, this exposes the most controls: see the Zigbee2MQTT documentation for more. There’s no clarity on what various pieces such as room load, etc, do so if you want the advanced setup then you may be best off using the official app. The ability to have 2 radiators in the same room working collaboratively is interesting, as I do have 2 rooms in the house with multiple radiators, however I don’t really want to set up another app to test this. I do think the control to tell the TRV whether heat is available (ie boiler is on) is an interesting one as it may mean the TRV doesn’t waste power when it’s summer (and running on local schedule) and secondly it may also mean it can self calibrate better.

It does return heating demand (valve position), but does not allow valve position setting.

Power is provided from 2 AA batteries, which seem to have lasted over a year. No problems with standard rechargeables.

Overall, this is a nice device, simple to override manually with a display of set temperature, a good range of controls – not all of which are understood it seems – and good support. I’d consider these.

shelly

Shelly is quite possibly the device most geared towards those into home automation and DIY. The range of shelly products includes cheap Wifi (not Zigbee) connected switches, light bulbs, outlets, relays, temperature sensors, door sensors etc. The TRV was eagerly anticipated by the community, and by and large it’s now pretty good following improvements to the firmware. You can control it through the Shelly app, or it has its own web interface you can use to configure it, add it to your Wifi network, etc. I would recommend setting a static IP for these devices.

There’s two buttons on the top to alter temperature, and also a reset button around the back that you’ll need. You will need a blunt pointy thing to access the button. Thankfully the display only lights up when you push a button; you can set brightness in the app.

Setup via the app is a little hit and miss, so I’d recommend putting them in access point mode (which they default to), and manually configuring wifi settings, static ip etc using a browser. Through the app you can set schedules, set valve position directly (which is hugely useful if you’re trying to automate everything through external sensors). The situation is different in HomeAssistant though, as the integration only shows basic climate, allowing a choice of preset modes, and exposes the battery percentage.

There is an option to integrate via MQTT, which should expose more controls: I will update this review once I’ve tried this.

The valve is large. By far the largest here, however it does have its own built in rechargeable battery. Disappointingly, the rubber covers on the manual controls have yellowed in 6 months, suggesting they haven’t properly fixed the bromide-containing fire retardant.

Power is supplied via the integrated battery, which claims a battery life of up to 2 years. I’ve certainly had a year’s use out of them and they’ve not been flat, so this may be a credible claim. The charge port is USB-C, and that does appear to be for charging only as there’s no device recognised when plugging the cable into a PC.

This could be the ideal device, especially if it supported valve positioning through HomeAssistant. There’s no reason why it shouldn’t, it just needs the control exposing through the HomeAssistant integration. I do not know if this is planned. It is, however, not the prettiest of devices.

Drayton Wiser

The Drayton Wiser Smart TRV is a rebrand of the Schneider Electric Wiser TRV. Further details on the Zigbee2MQTT integration are here.

It’s a smart, small device. Physically the top can be rotated slightly, and springs back to central position. There’s no display, however there’s 3 LEDs which show status and actions – instructions on what the LEDs mean is here. Despite the lack of display, I think this is a good looking device.

Control-wise, it only exposes a climate card, with current temperature and target temperature, and erroneously shows fan/cool/dry/off options that AC units have. I’ve raised this as a bug on zigbee2mqtt. It also shows heating demand (or valve position). And that’s it.

Overall, I like this device, it’s only been installed for a day but seems to actively calibrate itself and not overshoot temperatures too badly.

Conclusions? There’s no perfect device, quite. I’d discount the Tuya on reliability grounds, and the Tado on the requirement for another interface rather than Zigbee. There’s annoyances with every device in one way or the other. Next steps are to set up scheduling, and then to replace my BEMS with a set of relays driven by HomeAssistant. (Gulp)