If you're looking for something to help plan and conceptualize how the HVAC system is represented in an energy model, there are a number of good suggestions in answers to this question.

If you're looking for a program to produce plans or schematics for design, here is a big comparison table of computer-aided design programs.

It's not totally clear to me whether you want to draw the HVAC system inside the energy modelling software or use another tool first? If within the energy modelling tool and you want to model the HVAC performance using EnergyPlus then DesignBuilder provides a godd schematic graphical representation of the EnergyPlus system as the example attached here C:\fakepath\DB FCU+VRF.jpg. This shows the schematic of an evaporatively cooled chiller (evaporative details not shown as schematic components but included in chiller data) serving one part of a building and a VRF system with heat recovery serving another. The DesignBuilder schematic shows how all these components and systems fit together in one schematic representation that is easy to navigate and edit.