Configuration

The Configuration pane is where you set up the HVAC equipment for each system. Equipment is defined by its components: you enable the components each unit has (coils, outside air, energy recovery, return air) and configure each one. To start from a common arrangement instead of building it component by component, apply a system preset.

The pane works one tier at a time, and the switcher at the top of the sidebar offers two: Systems (central units) and Zones (terminal units). Per-space airflows are not set here — balance them in Air Balancing, the next pane in System Design.

Click a unit in the sidebar list to open its data panel. Cmd/Ctrl-click adds another unit to the selection and Shift-click selects a range, so you can configure several units together. A unit that has no equipment configuration yet carries a dot with a Not configured tooltip.

Apply System Preset

A preset writes a complete equipment arrangement to the selected central units and to every terminal unit they serve. Select one or more systems, then click Apply System Preset at the top of the data panel. The button is on the Systems tier only — a terminal unit takes its arrangement from the preset applied to its system.

The dialog has two steps:

1. Select — choose a preset. The list shows only the presets for the project’s Project Type: four on a Commercial project, two on a Residential project
2. Preview — check the central unit and terminal unit diagrams the preset builds, shown in a cooling mode and a heating mode side by side, then click Apply Preset

Project Type	Preset	What it builds
Commercial	AHU TO VAV (W/ REHEAT)	Central air handler with cooling and heating coils feeding VAV boxes with reheat coils
Commercial	DOAS TO FCU	Dedicated outside air unit tempers ventilation air for fan coil units that handle zone loads
Commercial	ERV TO FCU	Energy recovery ventilator preconditions outside air for fan coil units that handle zone loads
Commercial	SINGLE-ZONE RTU	Packaged rooftop unit with gas heat and DX cooling serving a single zone directly
Residential	RESIDENTIAL HEAT PUMP	Split heat pump: outside air ducted to a zone unit with DX cooling and DX heating coils
Residential	RESIDENTIAL AC (W/ FURNACE)	Split system: outside air ducted to a zone unit with a DX cooling coil and gas furnace

Applying a preset replaces the whole equipment configuration of the selected systems and of every zone they serve. Existing components, component settings, and energy settings on those units are discarded. The Preview step names the system and zone counts before you confirm. Undo reverts the whole apply in one step.

Central Unit Configuration

Components

Components live on the unit’s airflow diagram, not in a separate form. Use Add in the diagram header to add one of six:

• Outside Air - The unit brings in outdoor air for ventilation
• ERV - An energy recovery wheel preconditions outdoor air with exhaust air
• Return Air - The unit recirculates return air
• Cooling Coil - The unit provides cooling
• Heating Coil - The unit provides heating
• Fan Heat - Accounts for the heat the supply fan adds to the airstream

Click a component on the diagram to open its settings. Every component has an Enabled switch and a Delete button, and the two differ in scope: Enabled applies to the current equipment mode only, while Delete removes the component from all modes.

Equipment Modes

Component settings are stored per equipment mode. Pick the mode in the selector at the top of the pane — it switches the mode that configuration updates apply to — and the diagram header repeats the same selector. Check which mode is selected before you change a component.

Outside Air

Outside Air Method determines the outdoor airflow:

• Sum of Spaces - Total of each space’s ventilation requirement, with the system’s Occupancy Diversity applied to the people component of each space
• Multi-Zone - ASHRAE 62.1 multi-zone calculation using system ventilation efficiency
• Percent - A fixed percentage of supply air, entered under Percent of Supply. HVAKR tags 100% as DOAS
• Custom - A fixed flow rate you enter under Custom Flow Rate

Percent is dropped from the list on a central unit that serves a decoupled terminal, because that unit’s outdoor air goes straight to the space rather than as a fraction of its supply.

ERV

For units with an energy recovery wheel, set the ERV Wheel Effectiveness — the fraction of the exhaust-to-outdoor-air temperature difference recovered.

Return Air

The Return Air component carries the return-side settings:

• Relief - When on, excess return air beyond the supply target is exhausted as relief. When off, the excess recirculates into the supply stream. Central units default to on, terminal units to off
• Return Duct Leakage - Return air lost from the duct
• Return Duct Heat Gain/Loss - Temperature the return air picks up or loses on the way back

Cooling Coil

• Coil Type - Chilled Water or Direct Expansion
• CHW ΔT - Chilled water temperature rise, for chilled water coils
• Cooling Supply Air Temperature - Design temperature of air leaving the coil; typically 55°F (13°C) for dehumidification

Heating Coil

• Coil Type - Heating Hot Water, Direct Expansion, Gas Fired, or Electric
• HHW ΔT - Heating water temperature drop, for hot water coils
• Heating Supply Air Temperature - Design temperature of air leaving the coil

Fan Heat

Set Heat Gain Type to say how the supply fan’s heat is entered:

• Power - Enter the motor power as Fan Heat Gain
• Temperature Rise - Enter the air temperature rise across the fan as Temperature Rise

Supply Outlet

The dashed port at the right end of the diagram is the Supply Outlet — the air leaving the unit for the ducts. Click it to set:

• Supply Duct Heat Gain/Loss - Temperature the supply air picks up or loses between the unit and the spaces
• Supply Duct Leakage - Supply air lost from the duct. HVAKR inflates the unit’s design supply airflow to cover it

The outlet is not a component: it has no Enabled switch or Delete button, and its two values apply to every equipment mode.

The return-side equivalents are not here — Return Duct Leakage and Return Duct Heat Gain/Loss belong to the Return Air component, and fan heat belongs to the Fan Heat component.

General

One unit-level setting sits in the sidebar under General, outside the diagram:

• Other System Inefficiencies - Miscellaneous system losses

Energy Configuration

For energy estimates, configure:

• Heating Equipment Type - Heat Pump or Gas Furnace
• Cooling SEER (BTU/W·hr) - Cooling efficiency
• Heating COP - Heat pump coefficient of performance
• Heating AFUE - Gas furnace efficiency
• Operating Schedule - 24/7, 9am-5pm, or a custom hourly schedule
• Hours of Warm-up and Warm-up Capacity - Morning warm-up before occupancy

Airflows at Peak

At the bottom of the data panel, a read-only table named for the selected mode — Cooling Airflows at Peak or Heating Airflows at Peak — compares the unit’s Design and Required airflow for Supply, Return, Exhaust, OA, and Differential. A differential past the balance threshold is flagged in the Design column. The table appears for a single selected unit only. Before the project calculates, every row reads zero.

Terminal Unit Configuration

Select a zone to configure its terminal unit. Terminals use the same six components, the same Add menu, and the same component settings as central units. A terminal’s diagram is the whole editor — its data panel holds no form fields of its own, only the diagram, any warnings, and the same Airflows at Peak table:

• Return Air - Whether the terminal recirculates zone air, with the same Relief and return-duct settings
• Cooling Coil and Heating Coil - The same coil type, ΔT, and supply air temperature settings as central units
• Outside Air - The same Outside Air Method choice, applied to the terminal
• Supply Outlet - The same Supply Duct Heat Gain/Loss and Supply Duct Leakage settings, on the terminal’s own outlet port. Terminal leakage inflates the terminal’s supply target, and the central unit serving it sizes to that inflated target

For example, a VAV box with hot water reheat is a terminal with a heating coil (Heating Hot Water) and no cooling coil, while a four-pipe fan coil has both coils.

General and Energy Configuration are central-unit settings and have no terminal equivalent. A terminal’s Pressure Loss is not set here either — it lives on the terminal unit in Layout, where it feeds the duct pressure calculations.

Warnings

A warning callout appears under the diagram when:

• The selected units have mismatched components — the units in a multi-unit selection do not share the same components. Reordering or adding a component deletes every mismatched component from the selection
• The unit misses its supply target — the supply leaving the unit is above or below the served spaces’ design supply. The callout names the difference
• Return duct heat gain is undercovered — the return duct heat gain accounts for only part of the ceiling-plenum cooling load, so the unit may be undersized. Central units only

Airflow Diagram and Psych Chart

Selecting a central unit or terminal unit in the Configuration pane — or a space in Air Balancing — shows an airflow diagram above its data. Click the chart button (Open the airflow diagram and psych chart) in the panel header to open a larger dialog with the diagram and a psychrometric chart side by side.

• Central and terminal units — the diagram shows the unit’s air states: mixed, coil-leaving, and supply. Its components connect these states. The chart plots the same states. The unit’s mixing, coil, and recovery processes connect them.
• Spaces — the diagram shows supply entering on the left and return and exhaust leaving on the right, with the differential below. For a decoupled terminal, direct outside air also enters on the left. The chart plots the space type’s indoor setpoint against the supply air the serving equipment delivers.

Comfort Zones

The chart shades one or more comfort zones. Each zone is a design condition a served space’s space type asks for: its cooling or heating setpoint ± its temperature range, and its target relative humidity ± its humidity range. Spaces that share the same design condition combine into one zone. The zone with the most floor area shades darkest. Hover a zone to see its Dry Bulb Min, Dry Bulb Max, RH Min, and RH Max.

A space with no space type, no setpoint, or no target humidity has no comfort zone to shade.

Space SHR Line

When a served space’s sensible heat ratio is available, the chart adds a dashed Space SHR line at that ratio’s slope — the split between sensible and latent heat the room itself carries, not the coil’s total split.

• Central and terminal units — the line runs through the floor-area weighted average setpoint of the served spaces. Where the unit’s supply point falls relative to the line shows whether the supply air carries the space load at the ratio the rooms actually split it.
• Spaces — the line runs from the supply air state toward the setpoint’s dry bulb (right in cooling, left in heating) and marks where it lands with an ×, unless the line reaches the saturation curve first, in which case no marker is drawn. When the setpoint sits off that landing, the supply air reaches the room drier or wetter than the space’s load split.

Verification

After configuration, verify:

• Capacity meets peak loads
• Airflow is adequate for ventilation
• Pressure drop is within limits
• Equipment selections are realistic