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51M38 SERIES 5/2
Table 3
Default Program Settings (Time & Temp.)
Programs Time Temp. − Heat Temp. Cool
All days − A 6:00am 70_F / 21°C 78_F / 26°C
All days − B 8:00am 62_F / 17°C 85_F / 29°C
All days − C 6:00pm 70_F / 21°C 78_F / 26°C
All days − D 10:00pm 62_F / 17°C 82_F / 28° C
Thermostat Output Table
Table 4 depicts the 51M38 thermostat output states for var-
ious input conditions.
Table 4
Thermostat Outputs
Condition W1 Y1 G
Gas Heat, Auto Fan
Heat Demand X
Cool Demand X X
No Demand
Gas Heat, Continuous Fan
Heat Demand X X
Cool Demand X X
No Demand X
Electric Heat, Auto Fan
Heat Demand X X
Cool Demand X X
No Demand
Electric Heat, Continuous Fan
Heat Demand X X
Cool Demand X X
No Demand X
NOTE − X = output is activated with 24VAC.
Technical Specifications
Thermostat Type
Electronic programmable thermostat for 1-Stage
Heat/1-Stage Cool, gas or electric heat, non−heat pump,
non−power robbing applications.
Power Supply Range
18VAC − 30VAC (24VAC nominal), 60Hz
CAUTION
24VAC is present on the terminals of the thermostat
bracket. If removing the thermostat from the wall,
use caution and avoid touching any of the connec-
tor terminals on the wall bracket.
Also, when working with the thermostat dip
switches, use a non−conductive tool and take cau-
tion to avoid making any contact with the circuit
board, its imprinted circuitry and its connector
prongs.
Temperature Display
Display Scale: Fahrenheit or Celsius user selectable (via
DIP switch; see figure 17)
Display range: 35°F (2°C) to 99°F (37°C)
Display resolution: 1°F (1°C)
Display Accuracy: +/−1°F
If the Fahrenheit/Celsius display must be changed, use a
plastic, non−conductive tool to push the dip switch to the
right position (see figure 17).
F/C (Fahrenheit/Celsius) switch
shown in Celsius position
Figure 17
Changing Fahrenheit/Celsius Setting
1
2
3
4
5
6
7
PLUG IN (Use Care To Avoid Bending Prongs.)
Indoor Temperature Measurement Range
Measurement Scale: Fahrenheit
Measurement Range: 35°F to 99°F
Measurement Resolution: 0.5°F
Measurement Accuracy: +/−1°F
Field Offset: via DIP switches to +/−3°F
Sampling Method: temperature measurements sampled
every 15 seconds. Displayed temperature is the average
of the last four measurements.
Outdoor Temperature Measurement Range
Measurement Scale: Fahrenheit
Measurement Range: −22°F to 122°F
Measurement Resolution: 1°F
Measurement Accuracy: +/−2°F
Temperature Setpoint Range
Setting range: 50°F (10°C) to 90°F (32°C)
Setting resolution: 1°F (1°C)