The hvac element is a child of the systems element. You can submit one or two instances of the hvac element. 
NameDescriptionTypeLengthRequiredOptions / Range
hvac_nameName of this system instancestring20Yeshvac1, hvac2
hvac_fractionFaction of conditioned floor area served by this systemfloatNo0 - 1
heatingInputs about the heating systemelementNo0 - 1 instance
coolingInputs about the cooling systemelementNo0 - 1 instance
hvac_distributionInputs about the ductselementNo0 - 3 instances
  • The hvac_name element must be submitted so that the correct instance of hvac is modified.
  • The total of both the hvac_fraction values must be equal to 1
  • If the heating/type is central_furnace, heat_pump, or gchp or the cooling/type is heat_pump, gchp, or split_dx, you must submit an hvac_distribution element