I have a garage / workshop with its own gas heat. The insulation isn’t great so normally I leave the existing dumb thermostat off. In the winter this means that the garage is often below freezing. I’m looking for an HA-compatible thermostat that will tolerate being in the “off” state in below-freezing conditions, and has minimum setpoint when in the heat state no higher than 45 degrees. I also noted that some thermostats have an emergency mode where they will kick on the heat if the temperature is below 35 or 40 even if the thermostat is set to off. Obviously that won’t work for me.
Does anybody have recommendations for thermostats that meet these needs? I tried a Centralite Pearl and it was great in the fall, but it freaks out and reports very high temperatures if the actual room temperature goes below freezing. The Sinope models seem promising but the spec sheet shows a minimum operating temperature of 0C/32F.
I’d prefer to just buy something, but my backup plan is generic_thermostat with a relay, temperature sensor, and dumb thermostat wired in series as a max temperature failsafe.
I have been looking into thermostats lately, but found most stuff overly complex or designed for use within some ecosystem of devices. I have gone the generic thermostat way and it has been really solid. Only sometimes when I reboot HA I need to turn them back on.
I wonder how you wire a dumb thermostat in series…
I wonder how you wire a dumb thermostat in series…
It’s something I’ve seen people with DIY smart thermostats do. You take an old mercury thermostat and wire it in series with the smart thermostat. The setting on the dumb thermostat acts a max temperature in case your smart thermostat locks up and is constantly calling for heat.
You can do the same thing but wired in parallel to act as a minimum temperature backup.
You could go with a Shelly 1 with a temperature add on. It would be WiFi controlled and you would create a generic thermostat. As long as it doesn’t get wet you are good.
Been thinking about this some more. The garage rarely gets below freezing, only when the outside temperature is in the low 20s for multiple hours. Outside of serious cold spells like we are currently in, that shouldn’t happen very often. The thermostat seems to work OK otherwise, so I am going to cheat a little. I have an ESP8266 with a relay shield. I flashed ESPHome and set an automation so that if the thermostat is reporting a temperature above 120F (i.e., the low temp bug is active) AND the thermostat system_mode is heat AND the thermostat running_mode is idle, the relay will trigger and bypass the thermostat, forcing the furnace on. Eventually the garage will heat up enough that the bug will clear itself, the thermostat will take over and the running_mode will change to heating and the relay will open.
It’s a hack but it solves the problem I have with the parts I already have. I’ll still be keeping my eye out for a better thermostat, but I think outside of maybe industrial equipment they just don’t exist.
Why don’t you just add a (few) dallas temp sensors to you ESP? I have several ESP with several temp sensors to feed the thermostats. That way there is no need for buggy thermostats.
I use the wired waterproof version. Costs just a few dollars/euro.
