How to model a simple rule based heating system in OpenStudio

I am a beginner with Open Studio and try to model a house with a simple rule-based furnace for my research project. I want to model a heating system that has a thermostat in one zone of the building that turns the heating system on and off. The logic is simple if the thermostat is set to 21C, when the room temperature reaches 20C the furnace and fan will turn on to provide the heat and when the zoon temperature becomes 22C the fan and furnace turn off. I have tried many different HVAC systems in Open Studio such as Airloop unitary system and gas furnace with different set points, but none of them can apply the same logic in my model. I really appreciate if someone can help me what I am missing here.

EnergyPlus has a fairly recent feature that can model this. You'll want to use the ZoneControl:Thermostat's Temperature Difference Between Cutout And Setpoint. So you would specify the setpoint as 21C and then specify this temperature difference field as 1C. When you use this feature, you will probably want to run EnergyPlus with very short timesteps to get the desired behavior. I don't know offhand if the openstudio application exposes this input.

Note that this is not a commonly used feature. Most use of EnergyPlus relies on longer timesteps (10 mins to an hour), where EnergyPlus calculates the fraction of the timestep that the HVAC system needs to operate to perfectly maintain the desired setpoint (21C in your case).