HRV units (Heat Reclaim Ventilation) are indoors that handling external air flow.
They do not have a standard set of regular indoor units. The functions that can be controlled:
-On/off
-Modes: Heat exchange/Auto/ByPass
-Fan speed
In majority of the Home Automation drivers, those special modes are not implemented, and the only functionality that can be done is On/Off (and sometimes Fan Speed).