Most of the available sensors as well as radiator valves work on batteries. This is something I like to avoid, there is always something not working because one of the many batteries requires replacement.
Now about the radiator valves, I have several radiators which are placed behind a ‘panel’ or at a location where it is not easy to replace a battery.
A wall outlet near a radiator is never a problem, so I was planning to us a USB power supply and a 3V step down converter to power the radiator valve.
I initially bough a Tuya, however it turns out, that after a power outage, the button must be pressed twice (calibration ?) before it starts working. This makes the external power supply rather useless.
Another option might be a Sonoff TRVZB. I do not want to buy this as well; it might have the same ‘feature’. Anynone here who has and knows the behaviour after
the batteries are replaced. Does it require button presses as well ?
Anyone else who did (or wants something similar) with a TRV ?
I was not planning to use the valve for autonomous temperature control. Like to have the temperature reading and be able to open or close it.
Some other options I have in mind:
Leave rechargable batteries in and trickle charge with a current source and a few mA. This is safe for the batteries and would keep them charged.
Use a mains powered thermal radiator valve and something to control it (e.g. wall socket)
Any other ideas ? or sugegstions for other valve. Preferably Zigbee, Tasmota would be fine as well.
The Sonoff TRVZB requires a single click after losing power to go from In to Ad, it then comes online, but it always needs that single click, othervise i’d install a “fake battery” that provided correct voltage via a battery-shaped placeholder.
If you are otherwise happy with your setup, you could add UPS module to it. They have commonly USB input, 18650 battery holder and 5V output. ~$2 in AE.
Some models have 3V output option, but for lower current…
I had Hive from a previous house, so when I moved and setup the CH I continued to use Hive including 5 new TRVs. but I did not want to worry about batteries.
They have been working great. The Hive TRVs do not need any interaction when coming back online. They do however lose the state of the child lock, but that’s a minor issue that can be fixed in the app (if needed).
However you are then locked into Hive. I am looking at migrating over to Hive2MQTT Local HA. Which will allow me to use the Hive TRVs without the cloud.
If I were to start over I’d not go with Hive, before this post at least, Hive do work seamlessly after a power cut.
Since you are using external power anyways then I would suggest a thermal actuator.
They are cheaper than TRVs and don’t have any buttons or other “smart” things that can be an issue.
Thermal actuator + smart plug + temperature sensor is generally cheaper than a TRV but give you a better temperature reading and (generally) a quieter experience.