Vent-Axia HR500 Heat Recovery Ventilation Controller has been designed specifically for use with Vent-Axia heat recovery ventilation units but may also be used to control other equivalent loads up to the stated rating. Facilities include on/off, heat recovery intake and extract, high and low volume extract, variable speed control and automatic control via electro-mechanical ON/OFF switched sensor, e.g. thermostat, timer relay, etc.