Smart Thermostatic Radiator Valves (eTRV's by MiHome) following Nest Thermostat


(Andy) #1

Hi all,

Please be gentle, this is my first post. Although I’m not the best at coding I’ve been having quite a bit of success creating basic codes that control various home automation tasks around my home; motion detection, intruder detection, lighting schedules etc.

I’ve really come to a dead end though with a little project that I’ve been working on and was wondering if anyone out there could help?

To simplify, the hardware I have is;

  • A nest thermostat named “Nest Thermostat Kitchen”, the thermostat works in Celsius. It shows current temperature and you can adjust it to a higher or lower set point by an Integral scheduler or manually.

  • A MiHome eTRV (Smart Thermostatic Radiator Valve) named “Kitchen Radiator eTRV”- this device can measure the ambient temperature and increase or lower the ambient temperature in the room by opening and closing the radiator valve based on a set point temperature (the valve compares the ambient temperature versus the set point temperature and if its lower it opens the valve letting heat through, and if its higher it keeps the valve shut stopping the heat).

I have added both devices to “my devices” in the Smartthings API and they show in the Smartthings app and in Webcore, both allow access to ambient temperature and set point settings.

What I want to do is get the TRV to copy the Nest device set points as and when the Nest set point changes, so if the nest set point rises (due to a schedule change or manual change) the radiator set point changes with it (follows it).

I absolutely don’t want the Nest to change its settings based on the TRV, I want the TRV to follow the Nest.

If anyone could help I would be very grateful.

Andy


(Yves Racine) #2

Hi, there is already an app for that based on the concepts of rooms/zones/schedules.

You can elect the Nest to be the master thermostat and all your eTRVs will follow its mode (cool, heat, eco, off) and its setpoints.

You can even turn on/off your eTRVs automatically according to your scheduled zones.

Refer to this thread:

All the use cases are described at the ST community wiki:

http://thingsthataresmart.wiki/index.php?title=ScheduleTstatZones#Configuration

The code is available for download at:

P.S. I’d recommend this Nest implementation to take advantage of all the ST standard capabilities and its resilience under any ST or Nest outages:

So, you should choose the Nest bundle at my store (which includes My Next Tstat and the ScheduleTstatZones smartapp).
Regards.


(Mark C) #3

can you just not set it to follow in the mihome app - a change to nest would then be a change to the trv


(Andy) #4

Hi Mark,

Tried that, its hit and miss for some reason…doesn’t work all the time.

Andy