Component advice needed, garage door sensor + garage heater thermostat

I’d like to leave my garage heater on continuously to 55* but don’t want it to run continuously if my garage door is open.

Currently I have a dumb marantec garage door opener, and a simple 2 wire thermostat (no power wire) for my garage heater.

I already have a smartthings hub, and couple ge z-wave smart dimmer switches.

I was thinking of this combo, and hoping smartthings could get me the rest of the way. Sorry for being a newb!

You have to make sure your garage heater can accept that type of therm.

The opener will definitely work.

For something quick and dirty and way less expensive and if your garage heater is pluggable, then you can use a tilt sensor with temp and a power plug.

Just cut power to the heater once the door is opened.

You can use the garage controller to figure out up/down status of the garage door but what about a Z-Wave or Zigbee relay to interrupt one of the two thermostat wires to your dumb thermostat? The only time the heater starts is when the circuit is complete.

I purchased a multi purpose st sensor for the garage door sensor,and wired up my old honeywell wifi thermostat to the garage heater.

2 problems:
#1 I can set up a routine to change the temp set point but how do I change the mode from heat to off and off to heat

#2 I only want this to work if I have the heat on… I don’t want the heat to always kick on when the garage door closes

Can you expand on this a little? does the Zigbee modem have to be connected to a PC the entire time? I’m trying to do some quick reading on Zigbee right now. The goal is the same though. Low voltage thermostat and a chamberlin myQ garage. Kill the heater when the door is open since gas bills are something that my wife and kids believe are non-existent.