WattMaster MG331-21-VAVCAV - Manual (Page 30)

Form: WMS-OE255-6-CO2Sensor-1B.doc
Page 1 of 3
VAV System
Description
The OE255 & OE256 CO
2
Sensors are
used in conjunction with various other
WattMaster controllers to monitor and
control CO
2
levels in the building envi-
ronment.
Some typical applications are:
•
Controlling ventilation in a building
where the occupancy varies fre-
quently
•
Controlling ventilation to ensure ex-
cess outside air is not causing en-
ergy waste
•
To ensure good air distribution
throughout building zones
The OE256 is used for monitoring room
CO
2
levels and is designed for wall
mounting in the required space. The
OE255 is designed to be mounted on the
return air duct of the HVAC unit and in-
cludes a aspiration box with a probe that
samples air from the return air stream.
Both models use the patented dual beam Absorption Infrared ™ technology. This technology provides a very accu-
rate and stable sensor that is guaranteed to maintain its accuracy for a minimum of 5 years between calibrations.
The OE255 & OE256 CO
2
Sensors accuracy is
±
50 ppm @1000 ppm. Annual drift is 10 ppm per year. Repeat-
ability is
±
20 ppm.
Application
Both models utilize a sub-base mounting plate with terminal blocks providing for quick and easy mounting and
wiring. The OE256 wall mounted sensor’s sub-base is compatible with standard junction boxes for ease of wall
mounting and wiring. A locking screw secures the whole assembly to the wall. The OE255 duct mounted sensor
has a enclosure with pickup probe assembly that is mounted to the ductwork. The standard sensor sub-base and
housing is then attached to the enclosure to provide for secure mounting of the sensor. The OE255 also is sup-
plied with a clear enclosure cover to seal the sensor from dust and dirt.
Technical Data OE255 & OE256 – CO
2
Sensor
Input Power 18-30 VAC RMS, 50/60 Hz
Half Wave Rectified
Power Consumption 1.75 VA Maximum Average
2.75 VA Peak Power
Operating Temperature 32 ° F to 122 ° F Operating Humidity 0-95% RH Non-Condensing
Sample Method Diffusion Or Flow –through
50-100 ml/min
Measurement Range 0 to 2000 ppm
(Adjustable to 10,000 ppm).
Sensitivity ± 10 ppm Resolution ± 1 ppm
Analog Output 0-10 VDC
4-20 mA
Agency Certification FCC Part 15 Class B
One Year Warranty WattMaster reserves the right to change specifications without notice
OE255 & OE256 – CO2 Sensor
3-1/4"
1-1/8"
5-5/8"