Change Stelpro thermostat temperature for specific period of time

I have a Stelpro Maestro Smart Thermostat (ASMT402AD) which controls a convector heater in a small entryway to my house. Since there seems to be no way to turn off the heater entirely (ugh), we keep it at the minimum temperature of 40F.

We use the space unpredictably, so can’t program the thermostat with a regular schedule. I would like to be able to quickly trigger a sequence of events (by manually running a scene, automation, etc. in the ST app) as follows:

  1. Raise the thermostat temperature to a warmer set point
  2. Wait a certain amount of time - say 90 minutes
  3. Reduce the thermostat temperature to our standard 40F

Seems simple enough, but I can’t figure out how to do this via Scenes or Automations (both of which only let me control the thermostat in degrees C, and don’t seem to actually control the thermostat at all… but that’s a different issue, I suppose). Is there a SmartApp that would work? Am I missing something obvious?

I think may be looking for this app which uses a motion sensor to do what you’re looking to achieve.