Appendix C: ApacheHVAC Component and Controller Limits
The limits on the number of component and controllers permitted in a single ApacheHVAC file support HVAC networks of approximately the numbers of zones indicated below. The actual number of zones will range from these values to approximately a dozen fewer than stated, depending upon the number of components and controllers outside of the multiplexed portion of the network.
4,000* zones in prototype single-zone systems, such as most 01–04 configurations, with each multiplex layer including the following:
- Principal room
- Non-principal room – separately exhausted space drawing air from the principal room (optional)*
- Return air plenum “room” component
- Active duct
- Heating coil
- Cooling coil
- Room unit (baseboard heater or similar)
- Junctions (1 to 4, depending on configuration)
- Proportional controllers (2 to 8, depending on configuration)
- On-off controllers (2 to 4, depending on configuration)
6,000 zones in prototype multi-zone systems, such as most 05–09 configurations, with each multiplex layer including the following:
- Principal room
- Return air plenum “room” component
- Active duct (2 per zone in dual-duct systems)
- Heating coil (2 per zone in stepped 2-stage electric reheat)
- Cooling coil (FCU and Chilled beam systems)
- Room units (1 to 2, depending whether for just heating or heating and cooling)
- Junctions (2 to 4, depending on configuration)
- Proportional controllers (4 to 10, depending on configuration)
- On-off controllers (2 to 6, depending on configuration)
4,000* on multi-zone DV systems, such as 09g, with each multiplex layer including:
- Principal room – occupied zone
- Stratified zone “room” component
- Return air plenum “room” component*
- Room units (1 to 2, depending whether for just heating or heating and cooling)
- Junctions (2 to 4, depending on configuration)
- Proportional controllers (3 to 5, depending on configuration)
- On-off controllers (2 to 4, depending on configuration)
3,000 on multi-zone UFAD systems, such as 07f, with each multiplex layer including:
- UFAD supply air plenum “room” component
- Principal room – occupied zone
- Stratified zone “room” component
- Return air plenum “room” component
- Cooling coil (fan-powered boxes and underfloor “chilled beams”)
- Heating coil (2 per zone in stepped 2-stage electric reheat)
- Junctions (5 per zone on UFAD systems)
- Proportional controllers (6 to 10, depending on configuration)
- On-off controllers (2 to 6, depending on configuration)
*The maximum number of single-zone systems in one ApacheHVAC file can be increased to approximately 6,000 by deleting the optional separately exhausted non-principal room component from all multiplex layers when this component is not needed. Similarly, the maximum number of zones within one ApHVAC file with all systems of configuration 09g could be increased to approximately 6,000 if the project had no return air plenums and these components were deleted from the systems.
The limits on numbers of specific component and controllers are as listed in the table below.
