> For the complete documentation index, see [llms.txt](https://docs.betterbuilding.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.betterbuilding.io/user-guide/2d-building/building/hvac/space-hvac/vrf-terminal-unit.md).

# VRF Terminal Unit

A VRF (Variable Refrigerant Flow) Terminal Unit connects to the VRF system and controls the flow of refrigerant to modulate the temperature in specific zones. These units typically include a fan coil and may offer heating or cooling functions based on the system's mode.

<figure><img src="/files/zChtFmCzSbLoSs3U87jb" alt=""><figcaption></figcaption></figure>

## Sizing

<figure><img src="/files/b9yDrVCffY1HnWv7b27u" alt=""><figcaption></figcaption></figure>

### Heating Capacity Sizing Ratio&#x20;

Specify the Heating Capacity Sizing Ratio, indicating the ratio of the heating coil to cooling coil size when using autosizing.

### Sizing Method

Specify the 'Sizing Method' by selecting from 'Autosize' or 'Manual'. Manual sizing requires completion of all numerical fields with valid entries.

### Supply Air Flow Rate - Cooling

Specify the Supply Air Flow Rate - Cooling as the terminal unit’s operating volumetric air flow rate in cubic meters per second during cooling mode.

### Supply Air Flow Rate - No Cooling

Specify the Supply Air Flow Rate - No Cooling as the terminal unit’s operating volumetric air flow rate in cubic meters per second when the cooling coil is inactive, and the previous mode was cooling.

### Supply Air Flow Rate - Heating

Specify the Supply Air Flow Rate - Heating as the terminal unit’s operating volumetric air flow rate in cubic meters per second during heating mode.

### Supply Air Flow Rate - No Heating

Specify the Supply Air Flow Rate - No Heating as the terminal unit’s operating volumetric air flow rate in cubic meters per second when the heating coil is inactive, and the previous mode was heating.

### Outdoor Air Flow Rate - Cooling

Specify the Outdoor Air Flow Rate - Cooling as the outdoor air volumetric air flow rate in cubic meters per second during cooling mode. This field is set to zero flow when the VRF terminal unit is connected to an AirTerminal:SingleDuct:Mixer object.

### Outdoor Air Flow Rate - Heating

Specify the Outdoor Air Flow Rate - Heating as the outdoor air volumetric air flow rate in cubic meters per second during heating mode. This field is set to zero flow when the VRF terminal unit is connected to an AirTerminal:SingleDuct:Mixer object.

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