Lennox ComfortSense 3000, ComfortSense C0STAT05FF1L Operation Manual

E2017 Lennox Industries Inc.

Dallas, Texas, USA

THIS MANUAL MUST BE LEFT WITH THE OWNER

FOR FUTURE REFERENCE

WARNING

Improper installation, adjustment, alteration, service or
maintenance can cause property damage, personal injury
or loss of life. Installation and service must be performed
by a qualified installer, service agency or the gas supplier

OPERATION MANUAL

C0STAT05FF1L CS3000

Commercial Programmable

Thermostat

CONTROLS

507518-02
5/2017
Supersedes 507518-01

C0STAT05FF1L 5/2 Day Programmable
Thermostat

The Lennox ComfortSense® 3000 Series Commercial
Programmable Thermostat, Model C0STAT05FF1L
(11Y05) is a 5/2 day programmable and 2-heat / 2-cool
electronic thermostat. 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.

This thermostat is suitable for 2‐stage heat / 2‐stage cool
applications using a gas or electric auxiliary heat source and
can also be used with an economizer.

Page 2

507518-02

The remote indoor sensor when connected and configured
will act as a room temperature sensor instead of internal
temperature sensor available with the thermostat. The dip
switch is used to select either built-in or external remote
indoor temperature sensor used for temperature control.

Table of Contents

5/2 Day Programmable Thermostat 1..............

General 2......................................

Initial Thermostat Power‐up 2.....................

Buttons, Backlight, Timers & Settings 3............

DAY/TIME - Set Day and Time 4..................

HEAT - Heat Mode 4............................

COOL - Cool Mode 5............................

HOLD - Temperature Hold Mode 6................

PROG - Thermostat Programming 7...............

FAN - Controlling Fan Operation 9.................

SETTINGS - Filter and Maintenance Reminders 10...

SETTINGS - Balance Point 11.....................

Service Indicator 12..............................

Thermostat RESET 12............................

Removing/Installing Thermostat 13.................

Default Thermostat Settings 13....................

Technical Specifications 13........................

General

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

Initial Thermostat Power‐up

When power is initially applied to the thermostat, the display
will appear as shown in figure 1.

FAN
ON
AUTO

SYSTEM
COOL
OFF

HEAT

12:88

88

AM
PM

ROOM

88

MO TU WE TH FR SA SU

SETPOINT

°

°

SERVICE

FILTER

MAINT

Hi
Lo

PROG A | B | C | D HOLD

Figure 1. Initial Power-Up Display

NOTE - Tables 3 on page 13 lists all of the system defaults.

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5/2 DAY PROGRAMMABLE COMMERICAL THERMOSTAT

At this point, the thermostat will be fully functional; its default
temperature set point (not shown) is 70°F. At this point, if the
equipment has been fully powered and if a heat demand
were present, the system would begin operating. UC
indicates unoccupied and OC indicates occupied.

NOTE - Temperature scale default is Fahrenheit units but
may be reset to show Celsius, if desired. See page 14.

Buttons, Backlight, Timers & Settings

Buttons are located behind the small door on the right-hand
side of the thermostat (see figure 2).

Heat

Prog

Fan

Settings

Cool

Day/Time

Hold

Enter

(DOOR
OPEN)

10:36

72

UC

HOLD

AM

PM

ROOM

MO

°

FAN

AUTO

SYSTEM
COOL

Figure 2. Thermostat Buttons

IMPORTANT

Do NOT begin pressing buttons until after you read the fol
lowing section describing each button.

A pale blue display backlight illuminates for 30 seconds
each time any button is pressed.

When PROG or DAY/TIME is pressed, a field begins
flashing, expecting another input. Start making changes
within 15 seconds or the HOME screen will return.

When an Arrow, HOLD, HEAT, or COOL button is pressed,
setpoint and temperature setting appears for 15 seconds. If
desired, start making changes within 15 seconds or the
HOME screen will return. The backlight will turn off 15
seconds after the HOME screen reappears.

WARNING

This product contains a chemical known to the State of
California to cause cancer, birth defects, or other
reproductive harm.

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507518-02

DAY/TIME - Setting the Day and Time

Press the DAY/TIME button and set the CURRENT hour,
minute, and day of week as follows:

1. “AM12” will flash on the screen. Press the up or down
arrows buttons to change the hour. (“AM” or “PM” must
correspond to time of day.) Press DAY/TIME OR, if

adjusting for daylight savings time, pressing ENTER
stores the single change and exits to the HOME screen,
bypassing minutes and day of week.

2. Minutes will flash. Use the up or down arrow buttons to
display the minutes past the hour. Press DAY/TIME.

3. Day “MO” (Monday) will flash. Use up or down arrow
buttons to display the current day. Day selections are
abbreviated as “MO“, “TU”, “WE”, “TH”, “FR”, “SA”, and
“SU”. Press DAY/TIME.

4. The HOME screen reappears; confirm day and time are
correct. This completes day and time setting.

HEAT - Using the Heat Mode

Enabling Normal Heat Mode

Use the HEAT button to enable or disable heat mode. If the
thermostat is in OFF or COOL mode, pressing the Heat
button enables Heat mode. This is indicated by HEAT in the
SYSTEM box as shown in figure 3.

Heat

Prog

Fan

Settings

Cool

Day/Time

Hold

Enter

5:30

UC

70

HOLD

AM

PM

SETPOINT

FAN

AUTO

SYSTEM

HEAT

MO

°

Figure 3. Turn Heat ON/OFF

Disabling Heat Mode

If the thermostat is in heat mode when the HEAT button is
pressed, then heat mode is disabled. This is indicated by
OFF in the SYSTEM box as shown in figure 4.

SYSTEM

COOL

OFF

75

ROOM

UC

°

Figure 4. Heat Mode Disabled

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5/2 DAY PROGRAMMABLE COMMERICAL THERMOSTAT

Heating Demand

The thermostat must be in heat mode in order to properly
control the heating equipment. In heat mode, when the
actual temperature is lower than the temperature set point
the thermostat detects a heating demand and activates the
heating equipment to satisfy the demand. Heating operation
is indicated by a flame icon in the SYSTEM box.

When the actual temperature rises above the temperature
setpoint, the flame icon will disappear. This indicates that
the heating demand has been satisfied and that the heating
equipment has been turned off.

There are two timers govern the restart of heating:

1. Minimum furnace off timer (1.5 minutes only for HG).

2. Minimum cycle timer (six minutes).
For example:
If heating has been on for over six minutes then minimum

cycle timer is already fulfilled. For HG (gas), it will restart
after 1.5 minutes. For HE (electric), it will restart
immediately.

If the heating has not been on for six minutes, it will make up
the six minutes during the off time. Therefore the lock out
time is never six minutes.

COOL - Using the Cool Mode

Enabling and Disabling Cool Mode

Use the COOL button to enable or disable cool mode as
desired. If the thermostat is in HEAT or OFF mode, cool
mode is enabled when the COOL button is pressed. This is
indicated by COOL in the SYSTEM box (see figure 5).

10:30

UC

70

HOLD

AM

PM

SETPOINT

MO

°

°

Heat

Prog

Fan

Settings

Cool

Day/Time

Hold

Enter

FAN
ON

SYSTEM

COOL

Figure 5. Turn Cool ON/OFF