Page 1
Series CDT and CDTR Duct Mount Carbon Dioxide/
[84.14]
11-49/64˝
®
Temperature/Relative Humidity Transmitter
Specications - Installation and Operating Instructions
Bulletin AQ-CDT/CDTR-3
Series CDT and CDTR Duct Mount Carbon Dioxide/ Temperature/Relative
Humidity Transmitters accurately monitor the CO
in schools, ofce buildings, and other indoor environments to help achieve LEED
certication. A non-dispersive infrared (NDIR) sensor is used to automatically correct
the measurement in both occupied and unoccupied buildings against aging effects. In
order to achieve a higher level of accuracy, the Series CDT includes digital barometric
pressure adjustment.
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 conguration purposes, the Series CDT and CDTR can be ordered with the Model
A-449 remote LCD display that can plug into the mini-connector port on the internal
circuit board. Menu items that can be accessed include: engineering units, relay output
set points, display conguration, transmitter output scaling, and ambient barometric
pressure.
Automated CO
The Series CDT and CDTR CO
with the ability to adjust the CO
intermittently occupied spaces. The ABC algorithm accounts for long term drift by
making small adjustments to it’s zero calibration point based on the lowest CO
readings it measures. CO
ABC algorithm. For environments occupied 24 hours per day it is recommended to
periodically expose the CO
2 Baseline Correction (ABC)
2 transmitters are maintenance free instruments
2 calibration by using the on-board ABC logic for
2 calibration adjustments are made every eight days by the
2 sensor to outside ambient air.
2 concentration and temperature
Ø1-15/64˝
[31.35]
[298.85]
1/8˝
[3.17]
Ø3-5/16˝
SPECIFICATIONS
Sensor: NDIR, 15 year life expectancy.
®
Range: CO
(for units congured with humidity output); Temperature: 32 to 122°F (0 to 50°C).
Accuracy*: ±40 PPM + 3% of reading (2000 PPM CO
(5000 PPM CO
±1°C @ 25°C.
Response Time: 2 min for 90% step change.
Temperature Limits: 32 to 122°F (0 to 50°C).
Humidity Limits: 0 to 85% RH (non-condensing).
Power Requirements: 16-35 VDC/19-28 VAC.
Power Consumption: Average: 2 watts; Peak: 3.75 watts.
Output: Current: 4-20 mA (max 500 Ω); Voltage: 0-5 VDC or 0-10 VDC (min 500
Ω); Relay: SPST NO 2A @ 30 VDC; RTD or thermistor per r-t curves (depending on
model).
Weight: 5.6 oz (158.8 g).
Agency Approvals: CE.
*The specied CO
operation in environments which are intermittently occupied.
INSTALLATION
2
Make sure all connections are in accordance with the job wiring diagram and in
accordance with national and local electrical codes. Use copper conductors only.
4-25/32˝
[121.44]
4-9/32˝
[108.74]
2: 0 to 2000 or 0 to 5000 PPM (depending on model); RH: 0 to 100%
2); RH: ±2% (for units congured with humidity output); Temperature:
2 accuracy is only guaranteed after three weeks of continuous
WARNING
Disconnect power supply before installation to prevent electrical
shock and equipment damage.
2-13/16˝
[71.44]
2); ±50 PPM + 5% of reading
DWYER INSTRUMENTS, INC.
P.O. BOX 373 • MICHIGAN CITY, INDIANA 46360, U.S.A.
CAUTION
CAUTION
CAUTION
NOTICE
transmitter to adjust to the current CO
NOTICE
days.
Use electrostatic discharge precautions (e.g., use of wrist straps)
during installation and wiring to prevent equipment damage.
Avoid locations where severe shock or vibration, excessive
moisture or corrosive fumes are present.
Do not exceed ratings of this device, permanent damage not
covered by warranty may result.
Upon powering the transmitter, the rmware version will ash on
the display. A warm up period of 30 minutes is required for the
Self calibration feature of the transmitter requires exposure to
normal outdoor equivalent carbon dioxide level once every thirty
Phone: 219-879-8000
Fax: 219-872-9057
2 concentration.
www.dwyer-inst.com
e-mail: info@dwyermail.com
Page 2
MOUNTING
TURE
CO
OUT1
OUT2
RL
SEN
SEN
ENTER PUSH BUTTON
OUTPUT SELECTION
RH OUTPUT SELECTION
TVO
0-20 mA
4-20 mA
0-10 mA
2-10 mA
1. Cut hole into duct large enough to insert probe.
2. Attach housing ears to duct using the two self-tapping screws provided.
3. Knock out an opening in the housing and attach an electrical tting to route
electrical wiring. PG11 and PG16 knockouts are molded into the housing.
WIRING
Use maximum 18 AWG wire for wiring to terminals. Refer to Figure 4 for wiring
information.
UP PUSH BUTTON
REMOTE DISPLAY
CONNECTOR
DOWN PUSH
BUTTON
CONFIGUATION
SWITCHES
Figure 1: Diagram of circuit board
Selection of Current and Voltage Outputs
Prior to wiring, verify that the current/voltage conguration switches (positions 1 and
2) are set to the desired output type. Refer to Figure 1 to locate the conguration
switches. See Figure 2 for diagram of the current/voltage selection switches. For
voltage output selection, the output can be 0-10 VDC, 0-5 VDC, 2-10 VDC or 1-5
VDC. See Figure 3 for the type of voltage output selection switches (positions 3 and 4).
TERMINAL
BLOCK
Current/Voltage Outputs
The transmitter may be wired for current or voltage output for both carbon dioxide and
temperature. The transmitter can be powered with either 16-35 VDC or 19-28 VAC.
Wire the transmitter according to Figure 4.
NOTICE
Thermistor and RTD Outputs
Thermistor and RTD passive outputs are located on terminals 7 and 8 and do not
require any power. Passive temperature outputs are not polarity sensitive.
Optional relay can be used as either a dry contact or low voltage
switched circuit up to 2 A at 30 VDC.
POWER
SUPPLY
12 34567
Figure 4: Active output wiring diagram
TEMP OR RH
M
RECEIVER
CO2
RECEIVER
RELAY
CONTACT
PASSIVE
TEMPERA
SENSOR
8
Y
RLY
LTAGE CURRENT
CO2 CONCENTRATION
0-10 V
Figure 3: Output range selection jumper
VOLTAGE CURREN
TEMPERATURE/
Figure 2: Current/voltage output
Selection jumper (PJ1 And PJ2)
2-10 V
0-5 V
1-5 V
ACCESSING MENU PARAMETERS
Step 1: To enter the menu structure, press “Up” and “Down” simultaneously for 5
seconds (display will show RON parameter).
Step 2: Press “Up” or “Down” to cycle between menu items.
Step 3: Press “Enter” to edit the value for the displayed menu item (SET will appear
on display).
Step 4: Press “Up” or “Down” to adjust the value of the menu item.
Step 5: Press “Enter” to save the changes (SET will disappear).
Step 6: Repeat Steps 2 through 5 for each of the parameters.
Step 7: To exit the menu at any time, press and hold “Down” and “Up” simultaneously
for 5 seconds or wait 10 seconds without pushing any buttons.
Page 3
Menu Descriptions
Maximum CO2 value
MAX
Displays the highest CO
2 concentration value observed by the sensor since
the last power cycle or reset.
Reset the MAX CO
2 concentration by pressing and holding the ENTER button
for 1 second.
Relay on set point
RON
Sets the CO
2 concentration which the optional relay is energized.
Low limit: 0 PPM
Factory setting: 1000 PPM
High limit: 2000/5000 PPM (depending on model)
Relay off set point
ROF
Sets the CO2 concentration which the optional relay is de-energized. Setting
value lower than RON provides direct action for detecting high concentrations
2. Setting value higher than RON provides indirect action for detecting
of CO
low concentrations of CO
2. “Up” or “Down” on the LCD display will be lit to
indicate when the relay is energized.
Low limit: 0 PPM
Factory setting: 950 PPM
High limit: 2000/5000 PPM (depending on model)
Display conguration
DSP
Determines the LCD display conguration during normal operation. The LCD
display can indicate the CO
(CDTR only) and CO
2 concentration, temperature, relative humidity
2 concentration combined with temperature or relative
humidity (CDTR only).
CH CO
CT CO
C CO
2 concentration and relative humidity (CDTR only)
2 concentration and temperature
2 concentration only
T Temperature only
H Relative humidity only (CDTR only)
Units selection
UNI
Temperature and barometric pressure measurements can be displayed in US
engineering units or SI engineering units. The factory default is to display US
engineering units.
US units °F for temperature and in Hg for barometric pressure
SI units °C for temperature and hPa for barometric pressure
TOL
Temperature low output range (CDT with active temperature only)
Sets the temperature for the lowest output (4 mA or 0 VDC).
Low limit: 32.0°F / 0.0°C
Factory setting: 32.0°F / 0.0°C
High limit: 122.0°F / 50.0°C
TOH
Temperature high output range (CDT with active temperature only)
Sets the temperature for the highest output (20 mA, 5 VDC or 10 VDC).
When TOH is set above TOL, the transmitter is direct acting and the output
will increase with an increase in temperature. When TOH is below TOL, the
transmitter is reverse acting and the output will increase with a decrease in
temperature.
Low limit: 32.0°F / 0.0°C
Factory setting: 122.0°F / 50.0°C
High limit: 122.0°F / 50.0°C
HOL
Humidity low output range (CDTR only)
Sets the temperature for the lowest output (4 mA or 0 VDC).
Low limit: 0.0%
Factory setting: 0.0%
High limit: 100.0%
HOH
Humidity high output range (CDTR only)
Sets the temperature for the highest output (20 mA, 5 VDC or 10 VDC).
When HOH is set above HOL, the transmitter is direct acting and the output
will increase with an increase in temperature. When HOH is below HOL, the
transmitter is reverse acting and the output will increase with a decrease in
temperature.
Low limit: 0.0%
Factory setting: 100.0%
High limit: 100.0%
BAR
Barometric pressure
Sets the typical barometric pressure for the location where the transmitter is
mounted. The factory setting is for standard pressure at sea level. Adjusting
the barometric pressure gives a more accurate measurement, especially
at higher elevations. Refer to the elevation charts in Figure 6 for typical
barometric pressures at a given elevation.
Temperature offset
OFT
Allows the user to add an offset to the measured temperature.
Range: ±5°C in 0.5°C increments (±9°F in 1°F increments)
Factory Default: 0°C
Humidity offset (CDTR only)
OFH
Allows the user to add an offset to the measured relative humidity.
Range: ±10% in 1% increments
Factory Default: 0% RH
CO
COL
2 low output range
Sets the CO
2 concentration for the lowest output (4 mA or 0 VDC).
Low limit: 0 PPM
Factory setting: 0 PPM
High limit: 2000/5000 PPM (depending on model)
CO
COH
2 high output range
Sets the CO
2 concentration for the highest output (20 mA, 5 VDC or 10 VDC).
When COH is set above COL, the transmitter is direct acting and the output
will increase with an increase in CO
2 level. When COH is below COL, the
transmitter is reverse acting and the output will increase with a decrease in
2 level.
CO
Low limit: 0 PPM
Factory setting: 2000/5000 PPM (depending on model)
High limit: 2000/5000 PPM (depending on model)
Low limit: 20.0 in Hg / 600 hPa
Factory setting: 29.9 in Hg / 1013 hPa
High limit: 32.0 in Hg / 1100 hPa
ABC
Automated baseline correction
Enables/disables the Automated Baseline Correction algorithm for disabling
in locations that experience elevated levels of CO
2 due to constant occupancy
of the area. Select “ON” to enable ABC and select “OFF” to disable ABC.
Factory Default: ON
Reset to factory defaults
RST
Resets all menu settings to their default value, and clears zero and span.
YES - Press and hold - button for several seconds to reset settings
NO - Press button to exit this menu item without resetting
Page 4
MAINTENANCE/REPAIR
Upon nal installation of the Series CDT/CDTR, no routine maintenance is required.
The Series CDT/CDTR is not eld serviceable and should be returned if repair is
needed. Field repair should not be attempted and may void warranty.
This symbol indicates waste electrical products should not be disposed
of with household waste. Please recycle where facilities exist. Check with
your Local Authority or retailer for recycling advice.
WARRANTY/RETURN
Refer to “Terms and Conditions of Sales” in our catalog and on our website. Contact
customer service to receive a Return Material Authorization number before shipping
the product back for repair. Be sure to include a brief description of the problem plus
any additional application notes.
US Customary Units
ft in Hg
0
400
800
1200
1600
2000
2400
2800
3200
3600
4000
4400
4800
5200
5600
6000
6400
6800
7200
7600
8000
8400
8800
9200
9600
10000
29.92
29.50
29.10
28.69
28.29
27.90
27.51
27.13
26.76
26.39
26.02
25.66
25.30
24.95
24.60
24.26
23.93
23.60
23.27
22.94
22.63
22.31
22.00
21.70
21.40
21.40
Figure 5: Elevation chart
SI Units
m hPa
0
100
200
300
400
500
600
700
800
900
1000
1100
1200
1300
1400
1500
1600
1700
1800
1900
2000
2100
2200
2300
2400
2500
1013
1002
990
979
968
957
946
935
924
914
904
893
883
873
863
853
844
834
824
815
806
797
787
779
770
761
RESISTANCE VS TEMPERATURE TABLE
Temperature Resistance Curves (in Ohms)
°C °F A B C D E F
-55
-67.0
-50
-45
-40
-35
-30
-25
-20
-15
-10
-5
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
105
110
115
120
125
130
135
140
145
150
-58.0
-49.0
-40.0
-31.0
-22.0
-13.0
-4.0
5.0
14.0
23.0
32.0
41.0
50.0
59.0
68.0
77.0
86.0
95.0
104.0
113.0
122.0
131.0
140.0
149.0
158.0
167.0
176.0
185.0
194.0
203.0
212.0
221.0
230.0
239.0
248.0
257.0
266.0
275.0
284.0
293.0
302.0
607800.00
441200.00
323600.00
239700.00
179200.00
135200.00
102900.00
78910.00
61020.00
47540.00
37310.00
29490.00
23460.00
18780.00
15130.00
12260.00
10000.00
8194.00
6752.00
5592.00
4655.00
3893.00
3271.00
2760.00
2339.00
1990.00
1700.00
1458.00
1255.00
1084.00
963849.00
670166.00
471985.00
336479.00
242681.00
176974.00
130421.00
97081.00
72957.00
55329.00
42327.00
32650.00
25392.00
19901.00
15712.00
12493.00
10000.00
8057.00
6531.00
5326.00
4368.00
3602.00
2986.00
2488.00
2083.00
1752.00
1480.00
1255.00
1070.00
939.30
816.80
712.60
623.60
547.30
481.80
425.30
376.40
334.00
297.20
265.10
237.00
Figure 6: Resistance vs temperature
915.50
786.60
678.60
587.60
510.60
445.30
389.60
341.90
301.00
265.80
235.30
208.90
186.10
289154.70
201049.80
141595.50
100943.70
72804.30
53092.20
39126.30
29124.30
21887.10
16598.70
12698.10
9795.00
7617.60
5970.30
4713.60
3747.90
3000.00
2417.10
1959.30
1597.80
1310.40
1080.60
895.80
746.40
624.90
525.60
444.00
376.50
321.00
274.65
235.98
203.58
176.28
153.18
133.59
116.88
102.57
90.30
79.74
70.59
62.67
55.83
100.00
101.95
103.90
105.85
107.79
109.74
121.32
123.24
125.16
127.08
128.99
130.90
132.80
134.71
136.61
138.51
140.40
142.29
144.18
146.07
147.95
149.83
151.71
153.58
155.46
157.33
78.32
80.31
82.29
84.27
86.25
88.22
90.19
92.16
94.12
96.09
98.04
111.67
113.61
115.54
117.47
119.40
783.2
803.1
822.9
842.7
862.5
882.2
901.9
921.6
941.2
960.9
980.4
1000.0
1019.5
1039.0
1058.5
1077.9
1097.4
1116.7
1136.1
1155.4
1174.7
1194.0
1213.2
1232.4
1251.6
1270.8
1289.9
1309.0
1328.0
1347.1
1366.1
1385.1
1404.0
1422.9
1441.8
1460.7
1479.5
1498.3
1517.1
1535.8
1554.6
1573.3
2394000.00
1646200.00
1145800.00
806800.00
574400.00
413400.00
300400.00
220600.00
163500.00
122280.00
92240.00
70160.00
53780.00
41560.00
32340.00
25360.00
20000.00
15892.00
12704.00
10216.00
8264.00
6722.00
5498.00
4520.00
3734.00
3100.00
2586.00
2166.00
1822.60
1540.00
1306.40
1112.60
951.00
815.80
702.20
606.40
525.60
N/A
N/A
N/A
N/A
N/A
LEED® is a registered trademark of the U.S. Green Building Council
©Copyright 2022 Dwyer Instruments, Inc. Printed in U.S.A. 3/22 FR# 444657-00 Rev. 1
DWYER INSTRUMENTS, INC.
P.O. BOX 373 • MICHIGAN CITY, INDIANA 46360, U.S.A.
Phone: 219-879-8000
Fax: 219-872-9057
www.dwyer-inst.com
e-mail: info@dwyermail.com
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