Systems

Systems in HVAKR represent the HVAC equipment that conditions your building. Each system includes central equipment and serves one or more zones.

System Concepts

What is a System?

A system includes:

• Central unit - AHU, RTU, or other central equipment
• Terminal units - VAV boxes, fan coils, etc.
• Ductwork - Air distribution network
• Zones - The spaces being served

System Types

Common system configurations:

• Single-zone - One thermostat controls the entire system
• Multi-zone - Multiple zones with terminal units
• VAV - Variable air volume with zone control
• VRF - Variable refrigerant flow

Creating Systems

Automatic System Creation

HVAKR can automatically create systems from unassigned zones:

1. Navigate to Building Model > Systems
2. Click Auto Group Zones (the wand icon) in the toolbar
3. HVAKR creates systems and groups unassigned zones into them immediately — there is no strategy dialog — and shows a toast with how many systems were created and zones grouped
4. Review the results on the canvas and adjust zone assignment as needed

Create a System

1. Navigate to Building Model > Systems
2. In the Systems panel, click Create System (or press N)
3. A new system named New System is added and selected automatically
4. Rename it and set its color in the System Data panel
5. Assign zones to the system (see below)

Systems are created empty — there is no system-type template to pick at creation. Configure the central unit, coils, and outdoor air afterward using the System Properties described below.

Assigning Zones

Assign Zones to a System

1. Select a system in the Systems panel
2. In the System Data panel, click Assign Zones
3. Click zones on the canvas to toggle their assignment — the hint bar reads Click a zone to toggle system assignment
4. Assigned zones appear in the system’s Zones list; remove one with the ✕ button
5. Click Done when finished

Zone Requirements

When zones are assigned:

• Airflow is calculated based on zone loads
• Terminal units are sized
• Ventilation is distributed to zones

System Capacity

The system calculates total capacity based on:

• Sum of zone peak loads (with diversity)
• Ventilation requirements
• Safety factors

System Properties

Central Unit

Configure the main air handling equipment:

• Components - Outside air, energy recovery, return air, cooling coil, heating coil
• Supply temperature - Leaving air temperature for cooling and heating
• Outdoor air - Ventilation airflow method

Terminal Units

For multi-zone systems, each zone’s terminal unit is configured by its components:

• Return air, cooling coil, and heating coil components
• Coil types and supply air temperatures
• Pressure loss

Ductwork

Duct system parameters come from the project’s duct types:

• Max velocity and max pressure drop
• Max height and liner thickness

System Calculations

Load Aggregation

System load combines zone loads:

• Sensible cooling load
• Latent cooling load
• Heating load
• Ventilation load

Airflow Calculation

Supply airflow based on:

• Peak sensible load
• Supply air temperature
• Minimum ventilation

Equipment Sizing

Size central equipment for:

• Peak system load
• Coincident outdoor air
• Part-load performance

Multiple Systems

System Per Floor

Common approach:

• Separate AHU for each floor
• Easier maintenance access
• Simpler duct routing

System Per Exposure

Alternative approach:

• Interior system (cooling only)
• Perimeter systems (heating and cooling)
• Better load matching

Central Plant

For large buildings:

• Central chiller plant
• Central boiler plant
• Systems connect to plant loops

Best Practices

1. Match system to building - Use appropriate system types
2. Consider maintenance - Accessible equipment locations
3. Plan for future - Size systems with growth capacity
4. Check diversity - System capacity vs. sum of zones
5. Verify ventilation - Adequate outdoor air for all zones