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The thermostat can operate 3 types of humidifiers:
Stand Alone
• The humidifier is not connected to the HVAC system.
• The thermostat Mode can be set to Heat, Cool, Auto or Off.
Steam
• The steam humidifier is ducted to the HVAC system.
• The thermostat Mode can be set to Heat, Cool, Auto or Off.
• Requires the system fan to turn on when operating.
Evaporative
• A drum style humidifier which requires the heating system to
operate to evaporate the water.
• This system requires the system fan to operate.
• The thermostat Mode must be set to Heat or Auto.
Humidifier Window Protection
During cold weather, condensation will form on windows when the relative humidity
(RH) is too high. The optional window protection feature automatically calculates the
indoor dew point based upon the outdoor temperature and the quality of the windows
installed. The humidifier is then operated to the highest possible RH that is below the
Humidify To setting.
Dehumidifier Operation
The thermostat controls the relative humidity (RH) by operating either the Accessory
1 or Accessory 2 relay. This is an installer configurable setting. When the RH is above
the Dehumidify To setting by 3%, the Accessory 1 or 2 relay is closed to operate the
dehumidifier. The dehumidifier is shut off when the RH reaches the Dehumidify To setting.
The thermostat can operate 2 types of dehumidifiers:
Stand Alone
• The dehumidifier is not connected to the HVAC system.
• The thermostat Mode can be set to Heat, Cool, Auto or Off.
DX Coil
• The HVAC cooling system is used for dehumidification.
• The Accessory 1 or Accessory 2 relay activates the DHUM
operation on the air handling unit to operate the system fan at low
speed.
• The cooling compressor Y1 and Y2 relays are operated. The
chilled DX coil condenses moisture from the air.
• The cooling system can over cool the room temperature by 2°F
(1°C) during dehumidification.
Ventilation with fresh outdoor air is important for maintaining indoor air quality. The
thermostat can operate a heat recovery ventilator (HRV) or energy recovery ventilator
(ERV) on a timer by closing the Accessory 1 relay to operate the ventilator fan at low
speed.
The thermostat supports water-to-air heat pump systems that absorb or reject heat to a
hydronic building loop. Whenever the heat pump compressor Y1 or Y2 relay is turned
on, the Accessory 1 relay closes to open a hydronic zone valve. This allows variable
speed pumps on the hydronic loop to operate at lower speeds when the heat pump is
off, thereby saving electrical energy.
HRV / ERV Ventilator Operation
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Heat Pump Loop Valve Operation
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