Rowlett

I’ve owned this unit for about a year and I can’t figure out how to turn the furnace on. I’ve gone as far as testing the furnace power. There is no thermostat to run the furnace anywhere, only a “system heat” Button. Ive only Ran the heat pumps in the ac units, I’ve never figured out how the furnace turns on. The thermostat for ac is dual zone and does not switch to a furnace mode. Am I missing something?