# Using a controller for a simple heating system

I am new to control modeling. Given the following problem: I want to control the heating of a house. Therefore, a top unit should be switched on (nominal load, no ramp up) as soon as the production of the main unit is above a certain level. How would you do this? Is it possible to set the output of a p-controller to a fixed value?

if main_unit < level:
top_unit = 0
else: