When creating an HVAC family parameter, specify the parameter type in the Parameter Properties dialog.
In the Family Editor, click Create tab
Properties panel 
(Family Types). In the Family Types dialog, under Parameters, click Add. For Discipline, select HVAC. For Type of Parameter, select one of the following.
Properties panel (Family Types). In the Family Types dialog, under Parameters, click Add. For Discipline, select HVAC. For Type of Parameter, select one of the following. | Name | Description |
|---|---|
| Density | Used to define the density of air, which affects pressure drop calculations. |
| Friction | Used to report the pressure drop due to friction. |
| Power | Provides the ability to format power units for mechanical purposes. |
| Power Density | Used to express power per area. |
| Pressure | Used to report static, total, and excess pressure in the System Inspector. |
| Temperature | Used to define thermal set points for heating and cooling loads. |
| Velocity | Used to define the speed of air in a duct. |
| Air Flow | Used to define the volume of air in a duct. |
| Duct Size | Used to define dimensions associated with duct fittings. |
| Cross Section | Not used. |
| Heat Gain | Used to input heat gain for cooling loads. |
| Roughness | Used to define roughness on duct, which affects pressure drop calculations. |
| Dynamic Viscosity | Used to define dynamic viscosity of air, which affects pressure drop calculations. |
| Air Flow Density | Used to report the air flow volume per unit area. |
| Cooling Load | Used to report cooling load. |
| Heating Load | Used to report heating load. |
| Cooling Load divided by Area | Used to format heating/cooling load results. |
| Heating Load divided by Area | Used to format heating/cooling load results. |
| Cooling Load divided by Volume | Used for check sums in the Heating and Cooling Loads report. |
| Heating Load divided by Volume | Used for check sums in the Heating and Cooling Loads report. |
| Air Flow divided by Volume | Used for check sums in the Heating and Cooling Loads report. |
| Air Flow divided by Cooling Load | Used to format heating/cooling load results. |
| Area divided by Cooling Load | Used to format heating/cooling load results. |
| Area divided by Heating Load | Used to format heating/cooling load results. |
| Slope | Used to format the slope of a duct segment. |
| Factor | Used to format the coil bypass value. |
| Duct insulation Thickness | Used to format the thickness of insulation on duct components. |
| Duct Lining Thickness | Used to format the thickness of lining on duct components. |