Seeking a battery powered Zigbee wall thermostat that works with ZHA ? A bridge too far?

HI All,

Starting to feel like this is a “bridge too far”…

I have HA running in an ESXI Virtual machine in the attic with a Sonoff USB dongle on hardware passthrough.

Try as I might, I cannot get Z2MQTT to work in this way - ZHA? - no issue!. plugs and plays
But Z2MQTT refuses to acknowledge the existence of the Sonoff (I even built a separate VM with no ZHA and tried to integrate it with Z2MQTT. Simply will not play)

So it seems I have little option but to control the central heating with ZHA ?

OK I’m up for the challenge!

Where the legacy thermostat is mounted there is no mains and to drop a fused spur from the attic into the studded void would be a complete nightmare as the attic is fully floored with 25 years of our stuff on top of it !

But I can buy a battery thermostat with LPD433? so…surely… I can buy a zigbee one ?
(I do not want to run LPD433 due to high signal levels in the radio band - both I and next door are amateur radio buffs - We live on a hilltop and wifi is also saturated but Zigbee seems to get through)

Well thus far the only one I have found (a tuya) paired up first time but didn’t offer any zigbee functions other than firmware management via ZHA - so back it went.

Is anyone aware of a thermostat that

  • is battery powered
  • Is white in colour
  • offers a pair of dry contacts to drive a combi boiler
  • Integrates directly into ZHA and gives me as a minimum
    – Set temperature up / down
    – Read temperature
  • Has a front panel manual override for those times when I am working away and my missus wants
    to change settings
  • is wall mountable

or is this - as I fear - a bridge too far ?

Many thanks in advance

Regards

BB

and:

Makes it more or less impossible.

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if it can be done at 433/ 868 MHz - why not 2.4GHz please ?

A relay with 433 MHz and battery powered?
Ok… show me…

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we had a Honeywell branded one on LPD 433 here when we moved in - because I operate radios in 430-440 MHz we took it out (i was interfering with it) and replaced it with a manual one. (the 433 side wasnt actually used for the combi boiler)

Sorry but I dont recall any model number. quite a few years ago now

Did you remember to present the USB stick to the VM? Before I switched to a ethernet based coordinator I used the same setup as you are trying to, did not have any issues. If you want help on getting this to work let me know :slight_smile:

Think of the energy budget required.

  • Small batteries (like AA + a boost/ buck convertor)
  • Relay (240V 10A? 24V? you don’t meniton your location)
  • Radio.

2.4GHz WLAN requires either:

  • Mains power
  • a box of replacement batteries

However…

  • Zigbee Sonoff TH01 temperature + humidity sensor work well with ZHA
  • Mains-powered WLAN relay mounted on the boiler
    • Sonoff Matter or plain WLAN
    • Shelly WLAN - wide range, very small, dry contacts
  • Advanced Heating control blueprint

I’m also looking at replacing older controls with a 4x relay ESP32E-WROOM board, 1-wire DS18x20 sensors and ESPhome to put the control into an embedded device. These WLAN boards are cheap, low bandwidth, have loads of I/O, no display, and needs mains power (mount on the S-plan/ Y-plan/ Zoned “control centre”).

If the WLAN APs can’t handle 2.4GHz IoT trickles of data, you have larger issues than a thermostat!

(Don’t buy Aqara kit for ZHA - I have useless Curtain drivers and T1 temp/ humid/ pressure kit)

If this helps, :heart: this post!

yes I did - I rebuilt HA on a completely separate physical server. ESXi reports it as an unknown device but lsusb recognises it perfectly on both VMs . Z2MQTT however does not acknowledge its existence.

I have 8 TRVs and light switches working on it with ZHA , but Z2MQTT just says “co-ordinator not found”

Either solution is a moot point however if I cannot find a thermostat to fit the requirements

PS - I appreciate ZHA and Z2MQTT on the same coordinator are mutually exclusive!

A relay draws a lot of power.
If we believe Google

Add to this the radio, which does not have to be that much but it will not work battery powered.

I’ve heard people using separate thermometer and relay as thermostat with this integration: GitHub - Alexwijn/SAT: The Smart Autotune Thermostat (SAT) is a custom component for Home Assistant that works with many compatible gateways for your boiler.

So your relay can be mains powered, right next to the boiler.

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No offence intended James and Hellis81 - but can we put this theoretical discussion to bed please?

it’s a “side quest” to the main goal of my post, and I like to try and keep things
succinct for those that may google this thread in the future looking to follow in
my footsteps.

Here is a battery powered, wall mounted zigbee thermostat - with contacts to drive a combi boiler

I bought one - it paired via ZHA, but only gave me firmware update options as its zigbee capabilities
so I sent it back.

I seek to replace it with another that will integrate into ZHA and offer me appropriate controls.

If there are no other models so be it .

But if someone out there knows of a model that hits the goal I would be most grateful for the details please as I cannot find one thus far.

Many thanks

Thanks Cyberbeni - very interesting !

Thats probably something i could do with RPI-GPIO as well, and I confess that I had overlooked that there are 2 ends of the boiler control cable to integrate to!! :slight_smile:

but, the challenge comes with the way the house has been built.

to explain:

directly opposite the thermostat on the wall, is a small bathroom, but with a large towel rail radiator
the proximity of the two (when the bathroom door is open) trips out the thermostat on the landing whilst the TRVs downstairs are still calling for heat (the landing thermostat is the only control for the boiler) .

Whilst your suggestion would certainly work, and work well , my concern is to manage situations where I am working away and something goes wrong leaving my wife to manage the setup

If I had a commercial thermostat controllable by zigbee , when the downstairs TRVs call for heat (lets say 19C) I can script the thermostat to (say) 24C until the downstairs TRVs themselves trip out, and once detected, by HA ,I can return the landing thermostat to 19C . we have 2 radiators (one on each floor) that do not have TRVs to dump the excess heat into and should the landing reach 24C via the bathroom heater when the door is left open then the thermostat would cut out the boiler as a “fail safe”

perhaps I am overthinking this ? Clearly I need to look further into this !

Many thanks - great suggestion!