Default Thermostat Settings
Default Thermostat settings are in table 1.
Table 1
Default Thermostat Settings
Mode | Heat |
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Setpoint | 70°F (or 21°C) |
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Fan | Auto |
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Filter Reminder | OFF (reminder setting = 0) |
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Equipment Protection | reset back to zero |
Timers |
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Technical Specifications
Thermostat Type
Electronic nonprogrammable thermostat for 1H/1C, heat pump with electric or gas backup heat source, non−power robbing applications.
Power Supply Range
18VAC − 30VAC (24VAC nominal), 60Hz
Temperature Display
Display Scale: Fahrenheit or Celsius user selectable (via DIP switches)
Display range: 35°F (2°C) to 99°F (37°C)
Display resolution: 1°F (1°C)
Display Accuracy: +/−1°F
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.
Temperature Setpoint Range
Setting range: 50°F (10°C) to 90°F (32°C)
Setting resolution: 1°F (1°C)
Fan Control
AUTO or ON modes.
Backup Heat Source Selection
Electric or gas furnace, selectable via DIP switch #5 (Aux or Dual, respectively). See also Thermostat Output section.
I/O Relays
All thermostat relays are latching type to minimize power consumption. See table 2.
| Table 2 |
51M33 Terminal Designations | |
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Connections | Description |
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O | Reversing valve, cool active |
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B | Reversing valve, heat active |
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R | 24VAC |
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G | Fan control |
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Y1 | First stage cooling/heating, compres- |
| sor generated |
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W1 | Auxiliary heating, furnace generated |
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L | Service Indicator |
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C | 24VAC common |
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E | Emergency heat |
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T | Outdoor temperature sensor |
| connection 1 |
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T | Outdoor temperature sensor |
| connection 2 |
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Equipment Protection Timers
Minimum Compressor OFF time: 5 minutes
Minimum Compressor ON time: 4 minutes
Minimum Furnace ON time: 3 minutes
Minimum backup furnace cycle time (elapsed time be- tween any furnace activation and the next furnace activa- tion): 6 minutes.
Minimum elapsed time between any compressor activation and the next compressor activation: 6 minutes.
NOTE − All protection timers (except the compressor OFF timer) can be over−ridden if a heating or cooling demand is initiated or terminated using the UP, DOWN, HEAT, or COOL buttons.
Equipment Protection Override
Both the minimum compressor OFF timer and the mini- mum equipment cycle timer can be over−ridden by press- ing and holding either the HEAT or COOL button down for 4 seconds.
Over−Temperature Protection
Thermal mechanical switch opens W1 at 93°F+/−6°F.
Filter Reminder
Settings of 0 (Off), 1, 3, 6 or 12 months are available. When programmed time has elapsed, a FILTER indicator is dis- played.
Balance Point
0°F (OFF) to 55°F, user selectable.
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