Lennox ComfortSense™ 3000 Series Model L3532H 5/2 Day Programmable Thermostat

L3532H 5/2 Day Programmable Thermostat

The Lennox ComfortSense™ 3000 Series model L3532H 5/2 day programmable electronic thermostat features a large, easy-to-read display and provides excellent temperature control. It includes a programmable filter change reminder, an equipment maintenance reminder, and a system check indicator to notify the user when the equipment requires service. The L3532H thermostat is suitable for heat pump, 3-stage heat/2-stage cool applications using a gas or electric auxiliary heat source. An optional outdoor temperature sensor provides auxiliary heat lockout, balance point operation, and dual-fuel compatibility.

General

These instructions are intended as a general guide and do not supersede local codes. Consult authorities having jurisdiction before installation. Check equipment for shipping damage. If damage is found, contact the last carrier immediately.

Introduction

This document describes the operation of the Lennox model L3532H thermostat. Refer to the installation manual for instructions regarding installation and wiring.

Initial Thermostat Power-up

When power is initially applied, the display will appear as shown in Figure 1. All display segments are momentarily activated as a normal part of thermostat initialization.

Home Screen

Within seconds, the Home Screen appears (Figure 2) with default settings. After approximately 1 minute of initialization, the actual room temperature is displayed. The default temperature setpoint is 70°F. The thermostat is now fully functional. If the equipment is powered and a heat demand is present, it will begin operating.

Note: Temperature scale defaults to Fahrenheit but can be reset to Celsius (see page 8).

Buttons, Backlight, Timers & Settings

Buttons are located behind the small door on the right-hand side of the thermostat (Figure 3).

Important Note: Do not press buttons until reading the following descriptions.

A pale blue display backlight illuminates for 30 seconds each time a button is pressed. When PROG or DAY/TIME is pressed, a field flashes, expecting input. Changes must be made within 15 seconds, or the HOME screen returns. When an Arrow, HOLD, HEAT, or COOL button is pressed, SETPOINT and the temperature setting appear for 15 seconds. Changes can be made within this time, or the HOME screen returns. The backlight turns off 15 seconds after the HOME screen reappears.

DAY/TIME - Setting the Day and Time

Press the DAY/TIME button to set the current hour, minute, and day of the week:

1. The screen will flash "AM 12”. Use the Up/Down arrow buttons to change the hour (ensure AM/PM is correct). Press DAY/TIME. Alternatively, pressing ENTER stores the change and exits to the HOME screen, bypassing minutes and day of week (useful for daylight savings time).
2. Minutes will flash. Use the Up/Down arrow buttons to set the minutes. Press DAY/TIME.
3. The day "MO" (Monday) will flash. Use the Up/Down arrow buttons to display the current day. Day selections are abbreviated: MO, TU, WE, TH, FR, SA, SU. Press DAY/TIME.
4. The HOME screen reappears. Confirm the day and time are correct.

HEAT - Using the Heat Mode

Normal Heat Mode

In normal heat mode, both the heat pump and the backup heat source are used. If the heat pump cannot provide sufficient heat (e.g., in very cold weather), the backup heat source is activated.

Emergency Heat Mode

In emergency heat mode, only the backup heat source provides heat; the heat pump is disabled. This mode is activated only when there is a heat demand.

Enabling Normal Heat Mode

Use the HEAT button to select normal heat mode, emergency heat mode, or to disable heat modes. If the thermostat is in OFF or COOL mode, pressing HEAT enables Heat mode, indicated by "HEAT" in the SYSTEM box (Figure 4).

Enabling Emergency Heat Mode

If the thermostat is in heat mode, pressing HEAT enables EMG. HEAT mode (Figure 5). If the thermostat is in normal heat mode when HEAT is pressed, emergency heat mode is enabled.

Disabling Heat Mode

If the thermostat is in emergency heat mode and HEAT is pressed, heat modes are disabled, indicated by "OFF" in the SYSTEM box (Figure 6).

Heating Demand

The thermostat must be in normal or emergency heat mode to control heating equipment. When the room temperature is lower than the setpoint (Figure 7), a heating demand is detected, and the heating equipment activates. Heating operation is indicated by a flame icon in the SYSTEM box.

When the room temperature rises above the setpoint, the flame icon disappears, indicating the demand is satisfied and heating has turned off. Heat pump operation is locked out for 5 minutes after a demand is satisfied. If another demand occurs during this interval, the flame icon will flash, but the heat pump will not run until the 5-minute delay elapses.

Note: The heat pump operates for at least 4 minutes, and the backup heat source for at least 3 minutes, if no buttons are pressed during a demand interval.

If the system supports 3-stage heating, various heating levels may be delivered. For small heat pump heating demands, "Lo" is displayed; for large demands, "Hi" is displayed (Figure 8).

COOL - Using the Cool Mode

Enabling and Disabling Cool Mode

Use the COOL button to enable or disable cool mode. If the thermostat is in HEAT or OFF mode, pressing COOL enables cool mode, indicated by "COOL" in the SYSTEM box (Figure 9).

If the thermostat is in cool mode, pressing COOL disables it, indicated by "OFF" in the SYSTEM box (Figure 10).

Cooling Demand

Set the thermostat to cool mode. If the room temperature is higher than the setpoint (Figure 11), a cooling demand is detected, and the cooling equipment activates.

Cooling operation is indicated by flashing snowflake icons. When the room temperature drops below the setpoint, the snowflake icons disappear, indicating the demand is satisfied and cooling has turned off. If the system supports 2-stage cooling, various cooling levels may be delivered. For small cooling demands, "Lo" is displayed; for large demands, "Hi" is displayed (Figure 11).

Note: If no buttons are pressed during a cooling demand, the equipment operates for at least 4 minutes. After a demand is satisfied, cooling operation is locked out for 5 minutes. If another cooling demand occurs during this interval, "COOL" and snowflakes will flash, but the equipment will not operate until the 5-minute delay elapses.

HOLD - Using Temperature Hold Modes

When HOLD is displayed on the HOME screen, the thermostat is in a temperature hold condition, ignoring program data and functioning like a non-programmable thermostat.

Adjusting Temperature Setpoint in Hold Mode

The setpoint represents the desired space temperature. The default setpoint in Hold mode is 70°F. To adjust, press the UP or DOWN arrow buttons (Figure 12). Each press adjusts the setpoint by 1 degree. The HOME screen reappears after about 15 seconds.

Permanent Hold Mode

From the HOME screen, press the HOLD button to set a permanent hold (program override). Use the Up/Down arrow buttons to adjust the hold setpoint. Press HOLD again to return to the program.

Temporary (2-Hour) Hold

From the HOME screen, press the Up/Down arrow buttons until the desired setpoint is displayed. "HOLD" flashes (Figure 13), overriding the program for 2 hours from the last button press, then returning to the program.

PROG - Thermostat Programming

The L3532H thermostat can be programmed for heating or cooling events (not both combined) for 5 consecutive days using 4 unique events per day. The remaining 2 days can have a different set of 4 events. The homeowner sets the days and temperatures.

To Change Consecutive Days

Press and hold the PROG button for 5 seconds. The 5-day period is displayed (default is Monday-Friday). Use the Up/Down arrow buttons to change to a different 5-day span (e.g., Saturday-Wednesday). Press PROG when finished (Figure 14).

To Set Program Events and Temperatures

Figure 15 provides an example of programming for a workweek and weekend. The 5-day bar graph shows programs A and C for occupied times (72°F), B for unoccupied (less heat), and D for sleeping (cooler). The 2-day graph supports day-long occupancy.

Note: Pressing ENTER during programming saves changes and exits to the HOME screen.

To program events and temperatures, perform the following steps once for Cool and once for Heat:

1. Press and release PROG. "AM 6:00", period "A", and the 5 consecutive days are displayed; "AM 6" flashes.
2. Use Up/Down arrows to select the desired hour; press PROG.
3. Use Up/Down arrows to select the desired minute; press PROG.
4. Use Up/Down arrows to select the desired temperature setpoint; press PROG.
5. Repeat steps 2-4 for periods B, C, and D.
6. Repeat steps 1-5 for the 2-day program.

Note: The thermostat does not automatically switch between heating and cooling. Manual selection is required at the change of seasons or for abnormal temperature swings.

FAN - Controlling the Fan Operation

Use the FAN button to select either continuous fan mode (ON) or auto fan mode (AUTO). Pressing the FAN button toggles between modes. A fan icon in the FAN box indicates the fan is running.

If continuous fan mode is enabled (ON displayed), the fan runs continuously regardless of heating or cooling equipment operation (Figure 16).

If auto fan mode is selected (AUTO displayed), the fan runs only when the heating or cooling equipment is running (Figure 17).

SETTINGS - Filter/Maintenance Reminders

The L3532H thermostat can remind you when the filter needs changing or when routine maintenance is required. These reminders are optional and must be activated.

Press the Settings button (Figure 17) once for Filter reminders or twice for Maintenance reminders (Figure 18), then use the Up/Down arrows to select intervals (Table 1). The default setting is OFF.

Table 1. Filter and Maintenance Reminders

Note: The HOME screen reappears about 15 seconds after the final arrow button press, or press ENTER to save and exit.

After the programmed interval elapses, the reminder is displayed (Figure 19).

After changing the filter or performing maintenance, reset the reminder by pressing the SETTINGS button for 4 seconds. The screen will blink to indicate the timer has been reset.

SETTINGS - Balance Point

Note: The balance point feature is only available with the optional outdoor sensor (X2658).

The balance point feature allows the measured outdoor temperature to govern heat pump and backup heat source operation. Use the SETTINGS button to access balance point settings. If the outdoor sensor is attached, press SETTINGS three times to access the Balance Point Settings screen (Figure 20).

The balance point can be set between 1°F and 55°F (-17°C to 13°C). A setting of zero disables the function. The default is 55°F.

To adjust, use the Up/Down arrow buttons. Each press increases or decreases the setting by 1°F. The HOME screen reappears after about 15 seconds.

Note: The balance point feature allows the outdoor temperature to vary by 3°F above or below the balance point to prevent excessive equipment cycling. For example, if the balance point is 40°F and the outdoor temperature is 35°F, the temperature must rise to 43°F before adjustment. If the outdoor temperature is 45°F, it must drop to 37°F before adjustment.

Service Indicator

When abnormal equipment operation is detected, the SERVICE indicator will flash on the screen (Figure 21). This signifies that the equipment requires service from a qualified technician.

Thermostat RESET

In rare cases of malfunction or after electrical disturbances (like storms or power outages), a thermostat reset may be necessary. This will delete all programming and settings.

Caution: When the RESET button is pressed, all settings revert to defaults, including the default program (see Tables 2 and 3).

The RESET button is recessed and unlabeled, located behind the door, below the SETTINGS button (Figure 3). Use a paper clip or small pencil to press it. All settings will reset to the defaults listed in the Default Thermostat Settings section.

Removing/Installing Thermostat

The thermostat hinges on tabs at the top of the subbase. No tool is needed for removal. Pivot the bottom of the thermostat outward (releasing snaps), then lift to remove.

To replace, position the top tilted toward the wall bracket, aligning tabs and slots. Pivot the bottom toward the wall until it snaps into place.

Default Thermostat Settings

Default settings are shown in Table 2, and default programs in Table 3.

Table 2. Default Thermostat Settings

Table 3. Default Program Settings

Technical Specifications

Thermostat Type

Electronic programmable thermostat for heat pump, 3-stage heat/2-stage cool. Supports 2 stages of heat pump heat and one stage of auxiliary (gas or electric) backup heat.

Power Supply Range

18VAC - 30VAC (24VAC nominal), 60Hz.

CAUTION

24VAC is present on thermostat bracket terminals. Use caution when removing the thermostat from the wall to avoid touching terminals. When working with DIP switches, use a non-conductive tool and avoid contact with the circuit board and its components.

Temperature Display

Display Scale: Fahrenheit or Celsius (user selectable via DIP switch, Figure 22).

Display Range: 35°F (2°C) to 99°F (37°C).

Display Resolution: 1°F (1°C).

Display Accuracy: +/-1°F.

To change Fahrenheit/Celsius display, use a plastic, non-conductive tool to push the DIP switch to the right position (Figure 22).

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 are 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).

Smart Setback Recovery (via DIP switch #6)

Smart Setback Recovery (SSR) affects how the thermostat responds to program events. If SSR is disabled, events occur at the scheduled time. If SSR is enabled, the thermostat reacts before the event time to ensure the desired temperature is reached exactly at the event time.

Fan Control

Available modes: AUTO or ON.

I/O Relays

All thermostat relays are latching type to minimize power consumption.

Table 4. L3532H Terminal Designations

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 furnace activations): 6 minutes.
• Minimum elapsed time between compressor activations: 6 minutes.

Note: All protection timers (except compressor OFF timer) can be overridden by initiating or terminating a heating or cooling demand using the UP, DOWN, HEAT, or COOL buttons.

Equipment Protection Override

The minimum compressor OFF timer and minimum equipment cycle timer can be overridden by pressing and holding either the HEAT or COOL button for 4 seconds.

Over-Temperature Protection

Thermal-mechanical switch opens W1, Y1, Y2, and E at 93°F +/-6°F.

Filter Reminder

Settings: Off, 1, 3, 6, or 12 months (of fan run time). When programmed time elapses, a FILTER indicator is displayed.

Maintenance Reminder

Settings: Off, 6, or 12 months (chronological time). When programmed time elapses, a "MAINT" indicator is displayed.

Service Reminder

The SERVICE indicator is displayed under these conditions:

• If 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
• If 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 retains programming, HOLD status, setpoints, mode settings, and reminder statuses for a minimum of 24 hours during a power loss. After 24 hours, programmed settings are lost and replaced with defaults.

Important Note: Power must be applied for at least six consecutive hours prior to a power loss for memory to be retained.

LCD Backlight

Activated for 30 seconds when any button is pressed. During electrical storms, the backlight may activate briefly; this is normal and stops after the disturbance passes.

Thermostat Operating Conditions

35°F to 105°F, 5% to 90% RH.

Thermostat Storage Conditions

-40°F to 185°F, 5% to 95% RH.

Table 5. L3532H Thermostat Outputs

Table 5 depicts the L3532H thermostat output states for various input conditions. The following notes describe terms used in the table:

• X = output is activated with 24VAC.
• BBP: outdoor temperature is below balance point.
• ABP: outdoor temperature is above balance point.
• In all cases, the state of the B terminal is opposite that of the O terminal.
• Data are tabulated for AUTO fan setting. If the fan setting is ON, the G output is activated in all cases.
• Upstage timers: 30 minutes (when upstaging from small to large demand); 15 minutes (HEAT MODE ONLY - when upstaging from large to very large demand).
• Temperature ranges for "SMALL/LARGE/VERY LARGE" demands are for guidance only; actual temperatures may vary.
• Small HEAT demand: below setpoint –0.5°F but above setpoint -1.5°F AND 30-minute upstage timer HAS NOT expired.
• Large HEAT demand: less than setpoint –1.5°F OR 30-minute upstage timer HAS expired.
• Very large heat demand: below setpoint –2.5°F OR 15-minute 2nd upstage timer HAS expired.
• Emergency heat demand: temperature is below setpoint –0.5°F (only if emergency heat is enabled).
• Small COOL demand: above setpoint +0.5°F but below setpoint +1.5°F AND 30-minute upstage timer HAS NOT expired.
• Large COOL demand: above setpoint +1.5°F OR 30-minute upstage timer HAS expired.