23
4. Sensors
The M3 unit controller is only compatible with L-Connection sensors provided with the unit or purchased separately as
specified in the Product Specification.
IMPORTANT
All 0-10VDC sensors require two separate twisted pair cables with shield. One cable is used for the 24VAC power and
one cable is used for the 0-10VDC output. Room sensors require a single twisted pair cable with shield. The shield
drain wires must be connected to the common at the unit field wiring terminal block only. The shield drain wires must
not be connected to common at the sensor. Non-communicating temperature sensors require single twisted pair wire
only.
4.1.
Temperature Sensors - Provided With Unit
The return air (RT16) and discharge air (RT6) duct probes and the outdoor air (RT17) are all two wire thermistors. The
resistance vs. temperature table is shown below:
Table 12. Resistance vs. Temperature
Temp. °F (°C)
Resi/-2%
Temperature °F
(°C)
Resi/-2%
Temp. °F (°C)
Resi/-2%
-40 (-40)
335,671
40 (4.4)
26,106
90 (32.2)
7,332
-20 (-28.9)
164,959
50 (10)
19,904
100 (37.8)
5,826
0 (-17.8)
85,323
60 (15.6)
15,313
120 (48.9)
3,756
20 (-6.7)
46,218
70 (21.1)
11,884
130 (54.4)
3,047
30 (-1.1)
34,566
80 (26.7)
9,298
4.2.
Room Sensor - Optional
Room sensor (A2) is a two-wire thermistor with 1k series resistor.
Table 13. Two-Wire Thermistor
Temp. °F (°C)
Resi/-2%
Temperature °F
(°C)
Resi/-2%
Temp. °F (°C)
Resi/-2%
40 (4.4)
27,102
60 (15.6)
16,313
80 (26.7)
10,299
45 (7.2)
23,764
65 (18.3)
14,474
85 (29.4)
9,249
50 (10)
20,898
70 (21.1)
12,882
90 (32.2)
8,529
55 (12.8)
18,433
75 (23.9)
11,498
4.3.
Relative Humidity Sensor - Optional
The indoor relative humidity sensor (A91) is an analog sensor with a 0-10VDC output over a relative humidity range of
0-100% relative humidity. The sensor is powered with 24VAC.
4.4.
Carbon Dioxide (Indoor Air Quality) Sensor - Optional
The indoor carbon dioxide sensor (A63) is an analog sensor with a 0-10VDC output over a carbon dioxide range of 0-2000
ppm as shown in the following table. The sensor is powered with 24VAC.
Table 14. Carbon Dioxide Range
Carbon
Dioxide PPM
DC Voltage
Carbon
Dioxide PPM
DC Voltage
Carbon
Dioxide PPM
DC Voltage
Carbon
Dioxide PPM
DC Voltage
0
0
600
3
1200
6
1800
9
200
1
800
4
1400
7
2000
10
400
2
1000
5
1600
8
