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Bard Manufacturing Company, Inc.
Bryan, Ohio 43506
www.bardhvac.com
Manual: 7960-902
Supersedes:
NEW
Date: 3-1-21
8403-096 Carbon Dioxide Transmitter
(Dwyer
®
CDT-2N40-LCD-RLY 002 Sensor)
SUPPLEMENTAL INSTRUCTIONS
Series CDT Wall Mount Carbon Dioxide Temperature
Transmitters accurately monitor the CO2 concentration and
temperature in schools, office buildings, and other indoor
environments to help achieve LEED® certification. For
increased sensor life, a single-beam dual-wavelength non-
dispersive infrared (NDIR) sensor is used to automatically
correct the measurement in both occupied and unoccupied
buildings against aging effects. The single-beam dual-
wavelength sensor technology provides the highest level
of accuracy compared to Automatic Baseline Correction
methods, which can unintentionally shift the calibration
based on CO2 levels and barometric pressure conditions. In
order to achieve a higher level of accuracy, the Series CDT
includes digital barometric pressure adjustment and the
ability to field-calibrate the sensor.
Universal outputs allow users to select the transmitter
output to be 4-20 mA, 0-5 VDC, or 0-10 VDC to work with
virtually any building management controller. An optional
relay with user adjustable set points can be used to control
exhaust fans, open actuated windows or dampers, or signal
a light or horn.
For applications that require visual indication, the Series
CDT can be ordered with an integral LCD display, Model
A-449 or Model A-449A remote LCD display that can plug
into the mini-connector port on the side of the transmitter.
The CDT can be configured to display temperature only,
CO2 only or CO2 and temperature together. Push buttons
are standard on the transmitters for access to the menu
structure, but the transmitter can be ordered without the
buttons. To prevent tampering, the action of the buttons
can be locked out using an internal dip switch selection.
Menu items that can be accessed include: engineering
units, relay output set points, display configuration,
transmitter output scaling, ambient barometric pressure
and field calibration of the transmitter.
Single-beam dual-wavelength sensor advantages:
•
Automatically corrects for aging effects in occupied
and unoccupied buildings*
-
Perfect for hospitals and manufacturing plants
that are occupied 24 hours per day
•
Measures actual unfiltered light intensity directly
-
Eliminates error from incorrect assumptions of
gas concentration in theoretical logic assumption
methods
* For buildings occupied 24 hours per day, it is
recommended that calibration be verified every 6 to 12
months depending on application.
