A quick write up of a recent project that turned out to be pretty handy.
My workshop/garage is heated with a forced air overhead furnace that's not very efficient so it's kept pretty low when not in use.
In fact it's normally kept at just below freezing by using a "variable calibration" with an old school mercury thermostat.
i.e. The thermostat is mounted on a lever that allows changing from a normal (calibrated) level orientation minimum 40F operation, to an angled ~25F (re-calibrated) minimum temperature.
One of the reasons I'd never installed a smart thermostat was nothing went low enough. At least nothing in my price range.
So this is the alternative solution that allows a basic automation of the furnace.
The costs were minimal since all this was sitting on a shelf.
An old Thermostat from a previous renovation.
Donor Tstat
A Sengled bulb that I'd picked up for cheap thanks to @smarthomeprimer and his Hack thread.
A high level trigger relay assembly that was left over from another project.
And a few wires, cables, etc.
The end result is a ZigBee controlled thermostat installed in parallel with the old re-calibrated thermostat that is either:
a. active and acts as a high temperature setpoint thermostat, or
b. inactive and the furnace is controlled by the old sub-zero calibrated thermostat.
The process was straightforward and relatively quick to implement.
- ZigBee module.
Pair the Bulb to Hubitat
Name it: "Shop Heat Thermostat"
Switch the driver to "Generic Zigbee Switch" to eliminate any on/off ramping.
1a. Harvest the ZigBee module from the bulb.
Again, thanks to @smarthomeprimer for his efforts.
-
Install module and relay in old thermostat using an old USB cable and some wires and velcro.
-
Mount the thermostat in your shop/garage wire in parallel with the old unit and plug into a 5V USB adapter.
Done.
No more walking into a cold shop and waiting for the heat or forgetting to turn off the heat.
This worked so well I did another one for someone without a hub using a Wi-Fi relay, works great as well.
