Lennox International Inc 51M37 51M42 Terminal Designations, Equipment Protection Timers

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Table 5

51M42 Terminal Designations

Term. Description

BReversing valve, heat active

O Reversing valve, cool active

R24VAC

Y1

First-stage cooling/heating, compressor

 

energized

 

 

W1*

Auxiliary heating, furnace energized

 

 

Y2

Second-stage cooling/heating, compressor

 

energized

 

 

E*

Emergency heat

GFan control

LService Indicator

C 24VAC common

T Outdoor temperature sensor connection 1

T Outdoor temperature sensor connection 2

*For most applications, E will be jumpered to W1. If sep- arate wires are not provided for both E and W1, jumper the E terminal to the W1 terminal on the thermostat sub- base. For applications involving the use of a balance point (whereby the outdoor temperature is to be used to restrict either heat pump operation or backup heat source operation), the outdoor sensor (part number X2658) MUST be installed.

Equipment Protection Timers

Minimum Compressor OFF time: 5 minutes

Minimum Compressor ON time: 4 minutes

Minimum Furnace ON time: 3 minutes

Minimum furnace cycle time (elapsed time between any furnace activation and the next furnace activation): 6 min- utes.

Minimum elapsed time between any compressor activa- tion 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, Y1, Y2, and E at 93°F+/−6°F.

Filter Reminder

Settings of Off, 1, 3, 6 or 12 (months of fan run time) are available. When programmed time has elapsed, a FILTER indicator is displayed.

Maintenance Reminder

Settings of Off, 6 or 12 (months of chronological time) are available. When programmed time has elapsed, a mainte- nance indicator

Service Reminder

The SERVICE indicator is displayed only under the follow- ing conditions:

Sif the thermostat Y1 terminal has been activated with 24VAC for at least 5 minutes, AND the L terminal is shorted to the R terminal;

OR

Sif the thermostat Y1 terminal has been activated with 24VAC for at least 5 minutes, AND the L terminal is shorted to the C terminal.

Power Loss/Recovery

Thermostat memory is retained for a minimum of 24 hours during a power loss (includes retention of clock setting, program information, HOLD status, programmed temper- ature setpoint, heat/cool and fan mode settings, filter re- minder status, maintenance reminder status, and equip- ment protection timers). After 24 hours of power loss, programmed settings will be lost and replaced with default settings.

IMPORTANT

Power must be applied for at least six consecutive hours prior to a power loss in order for memory to be retained for the specified time.

LCD Backlight

Activated for 30 seconds when any button is pressed.

NOTE − During an electrical storm or similar disturbance, the backlight may activate for a few seconds. This is nor- mal and will no longer occur after the electrical disturbance has passed.

Thermostat Operating Conditions

35°F to 105°F, 5% to 90% RH

Thermostat Storage Conditions

−40°F to 185°F, 5% to 95% RH

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505069M 07/05

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Contents 51M37 Merit Series Thermostat Buttons Buttons, Backlight, Timers & SettingsDAY/TIME − Setting the Day and Time Home ScreenHeat − Using the Heat Mode FANCool Mode Disabled Cool − Using the Cool ModeEnabling and Disabling Cool Mode Turn Cool ON/OFFI036 FAN PM I036 FANSettings − Filter/Maintenance Reminders FAN − Controlling the Fan OperationThermostat Reset Settings − Balance PointService Indicator Removing/Installing ThermostatDefault Thermostat Settings Technical SpecificationsOver−Temperature Protection Smart Setback Recovery via DIP switch #6Equipment Protection Timers Maintenance ReminderCooling Demands Thermostat Output TableHeating Demands 51M35 Merit Series 51M35 Merit Series Thermostat505049M 5/1/05 Heat/Cool Mode Disabled Heat − Using the Heat Mode Cool − Using the Cool ModeEnabling and Disabling Heat Mode Turn Heat ON/OFFHold − Using Temperature Hold Modes 1st press Removing and Installing Thermostat I0i451M35 Terminal Designations Gas Heat, Continuous Fan Thermostat OutputsGas Heat, Auto Fan Electric Heat, Auto Fan51M34 Merit Series 51M34 Merit Series Thermostat505048M 5/1/05 51M34 Series 5/2 I036 FAN OFF I0i4 51M34 Terminal Designations Heat Demand Cool Demand No Demand 51M39 Merit Series 51M39 Merit Series ThermostatI026 530 Heat/Cool Mode Disabled Cooling DemandI030 Auto − Using the Autochangeover Mode Copy a Programmed Day to An other Day Filter Maintenance Indicators Displaying Outside TemperatureCheck Outside Temperature Service Indicator FlashingDefault Program Settings Time & Temp Autochangeover Deadband Selection via DIP switch #7 Indoor Temperature Measurement RangeOutdoor Temperature Measurement Range 51M39 Terminal DesignationsThermal-mechanical switch opens W1 and W2 at 93F+/−6F Page 51M42 Merit Series Thermostat 51M42 Merit Series−Day Programmable Thermostat 505069M 07/05 Large Heat Heating Demand FAN Auto MID Reminder Settings Display Using Fan on I026 Default Program Settings − Time & Temp With Electric Backup no outdoor sensorTechnical Specifications 51M42 Terminal Designations 51M38 Merit Series 51M38 Merit Series ThermostatY/TIME button 51M38 Series 5/2 Hold − Using Temperature Hold Modes Repeat steps a and B for as many days as you Settings Thermostat Output Table 51M38 Terminal Designations

51M37 specifications

Lennox International Inc, a prominent player in the heating, ventilation, and air conditioning (HVAC) market, has made significant strides in innovation and technology in recent years. Among its notable offerings is the Lennox 51M37, a well-engineered component designed to enhance HVAC efficiency and reliability.

The 51M37 is primarily known for its advanced motor technology, incorporating ECM (Electronically Commutated Motor) design, which significantly reduces energy consumption compared to traditional motor systems. This motor type is key to Lennox's commitment to sustainability, as it not only maintains optimal performance but also minimizes the carbon footprint associated with residential and commercial heating and cooling tasks.

A standout feature of the 51M37 is its intelligent control system, which allows for more precise management of airflow and temperature. This technology can adapt to specific environmental conditions and consumption patterns, optimizing performance and providing substantial cost savings on energy bills. The integration of smart technology aligns with modern demands for energy efficiency and control, making the 51M37 a vital component in achieving higher energy ratings for HVAC systems.

In terms of compatibility, the 51M37 is engineered to work seamlessly with a variety of Lennox heating and cooling units, ensuring versatility for both new installations and retrofits. This compatibility enhances system integration, resulting in improved overall performance.

The construction of the 51M37 emphasizes durability and reliability, featuring high-quality materials that withstand the challenges of constant operation. Its robust design is perfect for diverse environments, ensuring that it functions reliably in both residential settings and commercial applications.

Another characteristic worth noting is the user-friendly installation process, allowing HVAC technicians to install the 51M37 with relative ease. This not only reduces labor costs but also ensures that the system can commence operation quickly without extensive downtime.

Overall, Lennox International's 51M37 embodies innovation, efficiency, and reliability in HVAC technology. With its advanced ECM motor, intelligent controls, and durable construction, it stands as a prime example of how modern HVAC solutions can lead to enhanced performance and energy savings. As the industry continues to evolve, products like the 51M37 will play a critical role in shaping the future of heating and cooling, aligning with sustainability goals and meeting the needs of consumers.
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