VVT Zone Controller 17
Wiring a CO2 sensor
Part #33ZCSPTCO2LCD-01 (Display model)
Part #33ZCSPTCO2-01 (No display)
Part #33ZCT55CO2 (No display)
A CO
2
sensor monitors carbon dioxide levels. As CO
2
levels increase, the VVT Zone Controller adjusts the
outside air dampers to increase ventilation and improve indoor air quality. These sensors also monitor
temperature using a 10K thermister.
A CO
2
sensor can be wall-mounted or mounted in a return air duct. (Duct installation requires an Aspirator
Box Accessory - Part #33ZCASPCO2.)
The sensor has a range of 0–2000 ppm and a linear 4-20 mA output. This is converted to 1-5 Vdc by a 250
Ohm, 1/4 watt, 2% tolerance resistor connected across the zone controller's CO
2
input terminals.
NOTE Do not use a relative humidity sensor and CO
2
sensor on the same zone controller.
Wiring specifications
Cable from sensor to controller: If <100 ft (30.5 meters) 22 AWG, unshielded
If >100 ft (30.5 meters) 22 AWG, shielded
Maximum length: 500 feet (152 meters)
To wire the CO2 sensor to the controller
#33ZCSPTCO2
1 Wire the sensor to the controller. See appropriate diagram below.
2 Verify that the RH/CO2 jumper is set to 0-5Vdc on the VVT Zone Controller.
3 Verify the J7 jumper on the sensor is set to 0-5Vdc.
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