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McQuay LIAF015 - User Manual

McQuay LIAF015
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McQuay Training and Development
Now that you have made an investment in modern, efficient McQuay equipment, its care should be a high priority.
For training information on all McQuay HVAC products, please visit us at www.mcquay.com and click on training, or
call 540-248-9646 and ask for the Training Department.
Warranty
All McQuay equipment is sold pursuant to its standard terms and conditions of sale, including Limited Product
Warranty. Consult your local McQuay Representative for warranty details. Refer to Form 933-43285Y. To find your
local McQuay Representative, go to www.mcquay.com.
This document contains the most current product information as of this printing. For the most up-to-date product
information, please go to www.mcquay.com.
LIAF015 / Version A: 03-23-09
Installation, Operation & Application Guide
LIAF015
Group: WSHP
Supercedes: N/A
Date: 03-23-09
Programmable Electronic Thermostat
7-Day Programmable, Auto Changeover, Fan Speed Control, Hardwire
Part No.668811101
Specifications
Electrical Rating: •24VAC(18to30VAC)
•3ampmaximumtotalload
•1ampmaximumperterminal
Temperature control ranges: 45°F to 90°F Accuracy: ± 1°F
System configurations: 1-stage heat, 1-stage cool, heat pump, gas, oil, electric
Timing: Anti-short Cycle: 5 minutes
Backlight Operation: 10 seconds
Terminations: C, RH, RC, W, Y, B, O, G1, G2, S1, S2
Important Safety Information
Table of Contents
Specifications ........................................................................................................................................ 1
Important Safety Information ................................................................................................................. 1
Package Contents/Tools Required ........................................................................................................ 1
ToRemoveExistingThermostat ............................................................................................................ 2
To Install Thermostat ............................................................................................................................. 2
RemoteSensorInstallation(Optional) ................................................................................................... 3
Wiring Diagram ...................................................................................................................................... 4
Configuration Mode ............................................................................................................................... 5
Starting the Thermostat ......................................................................................................................... 7
Testing the Thermostat .......................................................................................................................... 8
Mode of Operation ................................................................................................................................. 9
Operating Modes ................................................................................................................................. 10
Setting the Time and Day of the Week ................................................................................................ 11
Programming ....................................................................................................................................... 12
Simpleset
®
Programming ..................................................................................................................... 14
Lockout Function ................................................................................................................................. 14
Factory Preprogramming ..................................................................................................................... 15
Personal Program Schedule ................................................................................................................ 15
Troubleshooting ................................................................................................................................... 17
MORN DAY EVE NITE
HEAT HEAT HEAT HEAT
COOL COOL COOL COOL
THURSDAY
4
MORN DAY EVE NITE
HEAT HEAT HEAT HEAT
COOL COOL COOL COOL
FRIDAY
5
MORN DAY EVE NITE
HEAT HEAT HEAT HEAT
COOL COOL COOL COOL
SATURDAY
6
MORN DAY EVE NITE
HEAT HEAT HEAT HEAT
COOL COOL COOL COOL
SUNDAY
7
Troubleshooting
Symptom Remedy
No display Check for 24 VAC at thermostat; display is blank when 24 VAC is not
present
System fan does not come on properly Verify wiring is correct
All thermostat buttons are inoperative Verify 24 VAC is present; unit locks out when 24 VAC is not present
No response with first button press First button press activates backlight only
Program schedule activates at the wrong time Checktime(AM/PM)setonthermostat(see“SettingtheTime,Page
11)
Thermostat turns on and off too frequently Adjusttemperaturedifferential(see“CongurationModeSetting2,
Page5)
Thermostat does not follow program
Verifyitisoperatinginprogrammode(PROGdisplays);checktime
(AM/PM);checkifin2hourprogramoverride
Fan runs continuously
Check Fan On/Auto switch, fan runs continuously in On position
Status indicator light not on during call Turn status indicator function on
(see“CongurationModeSetting10,Page7)
Room temperature is not correct Calibrate thermostat (see“CongurationModeSetting8,Page7).
If remote sensor is used, check S1 and S2 terminal connections
LOC displays when any button is pressed Thermostathasthebuttonlockoutfunctionactivated(see“Lockout
Function,Page14)
– – on display instead of room temperature Check for a bad connection at S1 and S2 terminals, if used
Problem not listed above Press Reset button once*
* Reset Button Function:
Time,dayandmodechangedtolastsavedsettings(savedafterpowerlossorwhenexiting
programsetup),congurationandprogramsettingsareunchanged.
•7-DayProgrammable
•Single Stage Heat Pump/Non-Heat Pump Systems
•BacklitDisplay
•SingleStageHeat/CoolSystems
•TwoSpeedFanControl
•FieldCalibration
•AutoChangeover
•ButtonLockoutFunction
•SimpleSet™Programming
•RemoteTemperatureSensorCapability
•Title24Compliant/NoBatteriesRequired
•RelayOutputs(minimumvoltagedropinthermostat)
•IdeallySuitedfor:
–Residential(NewConstruction/Replacement)
– Light Commercial
For replacement parts call 1-800-377-2787
©2008McQuayInternational•www.mcquay.com•800-432-1342
For replacement parts call 1-800-377-2787
©2008McQuayInternational•www.mcquay.com•800-432-1342
1. Turn off power to the heating and cooling system by removing the fuse or switching the appropriate circuit breaker
off.
2. Removeoldthermostat.Thisshouldexposethewires.
3. Labeltheexistingwiresbeforeremovingwires.
4. After labeling wires, remove wires from wire terminals.
5. Refer to the following section for instructions on how to install this thermostat.
To Remove Existing Thermostat
To Install Thermostat
IMPORTANT: Thermostat installation must conform to local and national building and electrical codes and
ordinances.
1. Turn off power to the heating and cooling system by removing the fuse or switching the appropriate circuit breaker
off.
2. Insertstripped,labeledwiresinmatchingwireterminals.See“WiringDiagrams”sectionofthismanual.
WARNING
Besureexposedportionofwiresdoesnottouchotherwires.
WARNING
ELECTRICAL SHOCK HAZARD – Turn off power at the main service panel by removing the fuse or
switching the appropriate circuit breaker to the OFF position before removing the existing thermostat.
WARNING
ELECTRICAL SHOCK HAZARD – Turn off power at the main service panel by removing the fuse or
switching the appropriate circuit breaker to the OFF position before removing the existing thermostat.
3. Tighten screws on terminal block. Gently tug wire to be sure of proper connection. Double check that each wire is
connected to the proper terminal.
4. Remove unused Gas/Electric jumper. Keep gas for oil or gas systems. Keep electric for heat pumps or electric
heat systems.
5. Replace thermostat by snapping it in place.
6. Turn on power to the system at the main service panel.
7. Testthermostatoperationasdescribedin“TestingtheThermostat”.
Remote Sensor Installation (Optional)
1. Remove cover from remote sensor housing.
2. Select an appropriate location for mounting the remote sensor.
3. Mount remote sensor unit using hardware provided.
4. Install two strand shielded wire between remote sensor and thermostat. Shielded wire must be used. Do not run
remote sensor wire in conduit with other wires.
•Wire 1 should run between the S1 terminal on the thermostat and the S1 terminal on the remote sensor
•Wire 2 should run between the S2 terminal on the thermostat and the S2 terminal on the remote sensor
•ConnecttheshieldingofthewiretotheS2terminalonthethermostat
5. Disablethemainsensor(R12)onthethermostatbycuttingitfromthecircuitboard.
WARNING
Always turn off power at the main power supply before installing, cleaning, or removing thermostat.
• Thisthermostatisfor24VACapplicationsonly;donotuseonvoltagesover30VAC
• Donotshortacrossterminalsofgasvalveorsystemcontroltotestoperation;thiswilldamageyourthermostat
and void your warranty
• Allwiringmustconformtolocalandnationalelectricalandbuildingcodes
• Donotuseairconditioningwhentheoutdoortemperatureisbelow50degrees;thiscandamageyourA/Csystem
and cause personal injuries
• Usethisthermostatonlyasdescribedinthismanual
Package Contents/Tools Required
Package includes: McQuay 668811101 programmable thermostat and Operation and Application Guide.

Questions and Answers

  • T
    Tammy RitterAug 19, 2025
    What to do if my McQuay Thermostat displays no room temperature?
    • T
      tgregorySep 12, 2025
      If your McQuay Thermostat shows '--' instead of the room temperature, it could indicate a connection issue. Check for a bad connection at the S1 and S2 terminals, if they are in use.
  • D
    David LopezAug 21, 2025
    Why does my McQuay LIAF015 fan run continuously?
    • J
      Jennifer TuckerAug 21, 2025
      If the fan on your McQuay Thermostat runs continuously, check the Fan On/Auto switch. The fan will run continuously when the switch is in the On position.
  • C
    Catherine HoganAug 25, 2025
    What to do if my McQuay LIAF015 is not displaying anything?
    • F
      Francisco SmithAug 25, 2025
      If your McQuay Thermostat display is blank, check for 24 VAC at the thermostat. The display will be blank if 24 VAC is not present.
  • M
    maryliAug 26, 2025
    Why are all the buttons on my McQuay Thermostat not working?
    • E
      Elizabeth ShortAug 26, 2025
      If all the buttons on your McQuay Thermostat are inoperative, verify that 24 VAC is present. The unit locks out when 24 VAC is not present.
  • S
    smithjustinAug 28, 2025
    What to do if my McQuay Thermostat is showing LOC when I press a button?
    • M
      Michelle GarciaAug 28, 2025
      If your McQuay Thermostat displays 'LOC' when any button is pressed, the button lockout function is activated. Refer to the 'Lockout Function' section on Page 14 to deactivate it.
  • K
    Kerri JenningsAug 30, 2025
    Why does my McQuay LIAF015 Thermostat turn on and off too frequently?
    • S
      sara66Aug 30, 2025
      If your McQuay Thermostat is turning on and off too frequently, you may need to adjust the temperature differential. Refer to 'Configuration Mode Setting 2' on Page 5 for instructions.
  • D
    Dan FlynnSep 1, 2025
    How to fix incorrect room temperature on McQuay LIAF015?
    • D
      Donald HoltSep 2, 2025
      If the room temperature displayed on your McQuay Thermostat is not correct, calibrate the thermostat. See 'Configuration Mode Setting 8' on Page 7 for instructions. If a remote sensor is used, check the S1 and S2 terminal connections.
  • W
    Wanda LeonardSep 4, 2025
    What to do if my McQuay LIAF015 isn't following the program?
    • P
      Peter CummingsSep 4, 2025
      If your McQuay Thermostat does not follow the program, verify that it is operating in program mode (PROG displays). Also, check the time (AM/PM) and whether it is in 2-hour program override.
  • J
    joshua02Sep 6, 2025
    Why does my McQuay Thermostat program schedule activate at the wrong time?
    • P
      Peter MartinezSep 6, 2025
      If the program schedule on your McQuay Thermostat activates at the wrong time, check the time (AM/PM) set on the thermostat. Refer to the 'Setting the Time' section on Page 11.
  • S
    Scott WilliamsSep 8, 2025
    What to do if my McQuay Thermostat system fan does not come on properly?
    • K
      kbaileySep 8, 2025
      If the system fan does not come on properly with your McQuay Thermostat, verify that the wiring is correct.

Summary

Getting Started

Specifications

Details electrical rating, temperature ranges, accuracy, and system configurations.

Important Safety Information

Critical safety warnings for installation, operation, and maintenance of the thermostat.

Removing and Installing the Thermostat

Step-by-step instructions for safely removing the old thermostat and installing the new one.

System Setup and Configuration

Configuration Mode Overview

Enters setup mode to match thermostat to specific heating/cooling system types.

Programming Features

Troubleshooting Guide

General Troubleshooting

Lists common symptoms and their corresponding remedies for thermostat issues.

Specific Troubleshooting Scenarios

Addresses issues like no display, button inoperability, and incorrect timing.

McQuay LIAF015 Specifications

General IconGeneral
TypeDigital
Voltage Rating24 VAC
DisplayLCD
BacklightYes
Holiday FunctionYes
Keypad LockYes
MountingWall mount
Battery BackupYes

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