Prototype systems: System-specific descriptions and guidance
Packaged Terminal Air-Conditioning (PTAC)
Packaged Terminal Heat Pump (PTHP)
Single-zone air-conditioning system with furnace (PSZ-AC)
Single-zone heat pump system (PSZ-HP)
VAV-reheat using DX Cooling and HW boiler
VAV using DX Cooling and parallel fan-powered boxes with electric heat
VAV-reheat using water-cooled chiller and HW boiler
VAV using water-cooled chiller and parallel fan-powered boxes with electric heat
To understand this system, start by understanding System 7 VAV reheat, and substitute parallel fan-powered boxes with 2-stage ER heat for the HW reheat coil.
The zone re-heat coil is two stage because that is how most electric-resistance coils in zone-reheat fan-powered boxes are set up and controlled---as two on/off coils each with a fixed output. This allows users to model this type of control/operation.
Parallel fan powered boxes have a fan that can run as needed for heating purposes (not all the time) and also has both primary (mixed air from the AHU) and secondary (recirculated room air) paths that are mixed together in the parallel box. Read up on parallel fan-powered boxes to learn more. A parallel fan-powered box takes air out of the room, mixes that with the primary airstream, and runs both through a heating coil and back to the room. The node immediately downstream of the room component on the network is effectively "in" the room—i.e., it sees the fully-mixed condition of that room. This node is the location on the network where air at the current room condition can be drawn from the room and recirculated back to the room.
The zone-level recirculation loop is the parallel fan-powered box, as described above. Because System 8 is a multi-zone VAV system with economizer damper set, just like other VAV re-heat systems but with fan-powered reheat boxes using ER coils in place of HW reheat coils, and not a dedicated outside air system, it must therefore also have a path for recirculating air at the system level.
Dedicated outside air system (DOAS) with four-pipe fan-coil units, EWC chiller and HW boiler.
Indirect-direct evaporative cooling version of VAV-reheat system 5 above with backup DX cooling and zone-level CO2-based demand-controlled ventilation (DCV).
VAV-reheat with differential-enthalpy economizer set up for the public areas of a hotel or similar building with PTAC systems for individual guest/resident rooms drawing air from an atrium zone on the main VAV system.
Mixed-mode natural ventilation and VAV-reheat with zone temperature and zone CO2 overrides for nat-vent when it is insufficient
Temperature and CO2-based overrides when not enough cooling or ventilation is provided via operable windows, in spite of favorable indoor-outdoor thermal conditions
Single-fan dual-duct and with zone-level mixing boxes.
Dual-fan-dual-duct with zone-level mixing boxes.
Underfloor air distribution with parallel fan-powered boxes for perimeter zones, leakage path, and heating-mode re-mixing of PFPb zones.
Can be used for thermal displacement ventilation by simply omitting the PFPb’s, UFAD plenum, leakage path, and re-mixing in heating mode.
UFAD/DV system as above, plus heat pipe or run-around coil in AHU for free re-heat of sub-cooled (dehumidified) air after the AHU cooling coil.
Figure 1 - 10 : Many elements shown here are common to other pre-defined prototype systems. The sections below describe these and many others.
Active chilled beams and DOAS for ventilation using electric water-cooled chiller with waterside economizer and condenser heat recovery; HW boiler and recovered heat for DOAS and zone baseboard fin-tube convectors.
Radiant heating and cooling panels (i.e., four-pipe system), plus DOAS with airside energy recovery and DCV.
Radiant panels and DOAS as above with heat pipe or run-around coil in AHU for free re-heat of sub-cooled (i.e., dehumidified) air after the AHU cooling coil.
PLEASE NOTE: This section of the ApacheHVAC User Guide is presently still under construction. Please be sure to check for updates.
