McQuay LIA303 Operation Manual
Installation, Operation & Application Guide
LIA303
Group: WSHP
Supercedes: N/A
Date: 03-23-09
Programmable Electronic Thermostat
1 Heat/1 Cool, Auto Changeover, Fan Speed Control, Hardwire
Part No. 668811301
For replacement parts call 1-800-377-2787
©2008 McQuay International • www.mcquay.com • 800-432-1342
• 7-Day, 5-2-Day or 5-1-1-Day Programmable
• Congurable
• Single-Stage Heat/Cool Systems
• Single-Stage Heat Pump Systems
• Two-Speed Fan Speed Selection
• Large Display With Backlight
• Selectable Fahrenheit or Celsius
• Compatible with Gas, Oil, or Electric
• SimpleSet™ Field Programming
• Status Indicator Light
• Relay Outputs (minimum voltage drop in thermostat)
• Remote Sensor Compatible
• Ideally Suited for:
– Residential (New Construction/Replacement)
– Light Commercial
Table of Contents
Parts Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Icon Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Specications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Important Safety Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Package Contents/Tools Required . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
To Remove Existing Thermostat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
To Install Thermostat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Wiring Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Remote or Outdoor Sensor Installation (Optional) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Conguration Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Conguration Mode Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Mode of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Operating Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Testing the Thermostat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Setting the Time and Day of the Week . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Programming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Lockout Feature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Factory Preprogramming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Personal Program Schedule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
SimpleSetTM Field Programming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
1
RESET CONFIG
RC
RH
Parts Diagram
Conguration switch
Reset switch
Left (system)
button
Right (fan)
button
Down button
Up button
Field programming pins
RC/RH jumper
FP
Fan Speed Switch
2
Specifications
Icon Descriptions
Fan operation icon
Cooling operation icon
Heating operation icon
Lock mode
activated
Room
temperature offset
activated
Electrical rating: • 24 VAC (18-30 VAC)
• 1 amp maximum per terminal
• 3 amp maximum total load
Temperature control range: 45°F to 90°F (7°C to 32°C) Accuracy: ± 1°F (± 0.5°C)
System configurations: 1-stage heat, 1-stage cool, heat pump, gas, oil, electric
Timing:
Anti-short Cycle:
4 minutes
Backlight Operation
Terminations: S1, S2, Y, W/O/B, G2, G1, RC, RH, C
3
Package Contents/Tools Required
Package includes: McQuay thermostat on base, thermostat cover, wiring labels, screws and wall anchors,
Installation, Operation and Application Guide
Tools required for installation: Drill with 3/16” bit, hammer, screwdriver
Important Safety Information
1. Turn off power to the heating and cooling system by removing the fuse or switching the appropriate circuit
breaker off.
2. Remove cover of old thermostat. This should expose the wires.
3. Label the existing wires with the enclosed wire labels before removing wires.
4. After labeling wires, remove wires from wire terminals.
5. Remove existing thermostat base from wall.
6. Refer to the following section for instructions on how to install this thermostat.
To Remove 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.
• 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
• Use this thermostat only as described in this manual
WARNING
Always turn off power at the main power supply before installing, cleaning, or removing thermostat.
4
To Install Thermostat
IMPORTANT: Thermostat installation must conform to local and national building and electrical codes and
ordinances.
Note: Mount the thermostat about ve feet above the oor. Do not mount the thermostat on an outside wall, in
direct sunlight, behind a door, or in an area affected by a vent or duct.
1. Turn off power to the heating and cooling system by removing the fuse or switching the appropriate circuit
breaker off.
2. To remove cover, pull gently at the seam at the top.
3. Put thermostat base against the wall where you plan to mount it (Be sure wires will feed through the wire
opening in the base of the thermostat).
4. Mark the placement of the mounting holes.
5. Set thermostat base and cover away from working area.
6. Using a 3/16” drill bit, drill holes in the places you have marked for mounting.
7. Use a hammer to tap supplied anchors in mounting holes.
8. Align thermostat base with mounting holes and feed the control wires through slit in thermal intrusion barrier and
into wire opening.
9. Use supplied screws to mount thermostat base to wall.
10. Insert stripped, labeled wires in matching wire terminals.
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.
11. Gently tug wire to be sure of proper connection. Double check that each wire is connected to the proper
terminal.
12. Turn on power to the system at the main service panel.
5
Hardwired
5-Wire, Single Transformer
Wiring Diagrams
13. Congure thermostat (see Page 12) to match the type of system you have.
14. Replace cover on thermostat by snapping it in place.
15. Test thermostat operation as described in “Testing the Thermostat” (Page 19).
6
Hardwired
6-Wire, Two Transformer
(Both transformers must be in phase)
Hardwired
5 or 6-Wire, Single Transformer
IMPORTANT: Before wiring, remove pre-installed
RC/RH jumper.
7
Hardwired
Cool or Heat Active Reversing Valve
8
Hardwired
5-Wire, Single Transformer
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