Safety Switch Input (A42−Optional) - Lennox Prodigy M2 Application Manual

3.10.2. Safety Switch Input (A42−Optional)
The M2 has a 24 volt optional input (DI−3) which may be used for additional safety switches (such as a blower overload, loss
of phase protector, or supply duct high pressure limit switch). Wire the safety switch in series with the input. When the input is
de−energized, the M2 will turn off all outputs and display error code #20 (ECTO 5.08). For normal operation, the input must
be energized with 24VAC.
ECTO ECTO
5.01 Single/Two Stage (2)
Blower
0 Off
1 On (1)
2 On (1)
3 On (1)
4 Off
5 On (1)
6 On (1)
7 Off
(1)−Blower with VFDs operation depends on ECTO 0.01 settings. If set to PID, supply static SP = ECTO 0.02, if set to staged, blower
speed = ECTO 0.02. For CAV units with bypass dampers, supply static SP= ECTO 0.13.
(2)−Both exhaust fan stages will operate on units with two stage fans.
4. Sensors
The M2 is only compatible with L connections sensors provided with the unit or purchased separately as specified in the
Engineering Handbook.
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. Zone 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.
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 resist-
ance vs. temperature table is shown below:
Temp. °F (°C) Resistance +/−2%
−40 (−40.0) 335,671
−20 (−28.9) 164,959
0 (−17.8)
20 (−6.7)
30 (−1.1)
4.2. Optional Zone Sensor
Zone sensors (A2) are two wire thermistor with 1k series resistor.
Temp. °F (°C) Resistance +/−2%
40 (4.4)
45 (7.2)
50 (10.0)
55 (12.8)
4.3. Optional Relative Humidity Sensor
The indoor Rh sensor (A91) is an analog sensor with a 0−10 Vdc output over an Rh range of 0−100%rh. The sensor is pow-
ered with 24Vac.
Table 7. Smoke Alarm Operation
Exhaust Fan
Off
Off
On Speed = ECTO 8.19
On Speed = ECTO 8.19
On Speed = ECTO 8.19
On Building Static SP=ECTO 8.19
On Building Static SP=ECTO 8.19
On Building Static SP=ECTO 8.19
Temp. °F (°C)
40 (4.4)
50 (10.0)
85,323 60 (15.6)
46,218 70 (21.1)
34,566 80 (26.7)
Temp. °F (°C)
27,102 60 (15.6)
23,764 65 (18.3)
20,898 70 (21.1)
18,433 75 (23.9)
Fresh Air Fresh Air
VFD Damper
Off Closed
Off Open
Closed
Open
Closed
Closed
Open
Closed
Resistance +/−2%
26,106
19,904
15,313
11,884
9,298
Resistance +/−2%
16,313
14,474
12,882
11,498
Page 15
4.
Description
Unit Off
Positive Pressure
Negative Pressure w/ Blower
Exhaust fan at fixed speed
Purge
Exhaust fan at fixed speed
Negative Pressure
Exhaust fan at fixed speed
Negative Pressure w/ Blower
Exhaust fan modulates
Purge
Exhaust fan modulates
Negative Pressure
Exhaust fan modulates
Temp. °F (°C) Resistance +/−2%
90 (32.2) 7,332
100 (37.8) 5,826
120 (48.9) 3,756
130 (54.4) 3,047
Temp. °F (°C) Resistance +/−2%
80 (26.7) 10,299
85 (29.4) 9,249
90 (32.2) 7,529
PRODIGYT M2 UNIT CONTROLLER
Sensors