Relative Humidity Operation - Tekmar Invita Installation, Operation And Maintenance Manual

Relative Humidity Operation

Relative Humidity Sensor
The thermostat includes an internal relative humidity (RH) sensor and has the option to connect to an
external RH sensor . The installer has the option to disable the internal RH sensor when an external
RH sensor is installed . When both the internal and external RH sensors are enabled, the RH reading
is averaged .
Humidifier Operation
The thermostat controls the relative humidity (RH) by operating either the Accessory 1 or Accessory 2
relays . This is an installer configurable setting . When the RH is below the Humidify To setting by 3%,
the Accessory 1 or 2 relay is closed to operate a humidifier . The humidifier is shut off when the RH
reaches the Humidify To setting .
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 . This feature requires a wired outdoor
sensor to be installed .
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 .
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