gas coil not turning on

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I'm thinking that the reheat coil may be picking up all of the load. Or perhaps there is no heating load for another reason. Like the heating thermostat setpoint is exceptionally low, there are high loads and/or warm climate, or the gas coil has no capacity. It is true, that the HVAC library does not include an instance of the AirLoopHVACUnitarySystem with DX cooling, gas heating, and no reheat, but try setting the reheat coil's availability schedule to an "always off" schedule. You may then see unmet hours, but at least you'll be closer to diagnosing your system with the reheat coil disabled.

It will be helpful if you report back here with your findings. We can adjust the HVAC library to avoid setting the availability schedule if necessary.