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Honeywell T6 Pro Thermostat Manual: Installation & ISU Code Guide

Complete contractor installation manual and user operating instructions for the Honeywell Home T6 Pro Programmable Thermostat (TH6220U2000 / TH6320WF2003).

Verified Technical Resource: Extracted directly from official Honeywell / Resideo service manuals and verified by the LaptopsPapa Hardware Engineering Team.
ManufacturerHoneywell / Resideo
Model NumberTH6220U2000 / TH6320WF2003
DocumentationOfficial PDF
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Honeywell T6 Pro Hardware Overview

The Honeywell Home T6 Pro is built on the Universal Wall Plate (UWP) mounting system, supporting up to 2 Heat / 2 Cool conventional systems and up to 3 Heat / 2 Cool heat pump configurations.

HVAC Safety Notice: Always disconnect main power at the circuit breaker or furnace power switch before removing the existing thermostat or altering wiring. 24VAC circuits can blow the control board fuse if shorted.

UWP Terminal Installation Steps

  1. Mounting: Level and secure the UWP backplate to the wall using the provided drywall screws and anchors.
  2. R Slider Tab Configuration: For single-transformer systems (1 R wire), leave the built-in R Slider Tab in the UP position. For dual-transformer setups (separate R and Rc), slide the tab DOWN.
  3. Wire Insertion: Depress the spring-loaded terminal tabs and insert stripped wire ends (1/4-inch exposed copper) firmly into their labeled slots.
  4. Attach Display: Align the terminal pins and push the T6 Pro housing onto the UWP until it clicks into place.

Comprehensive Installer Setup (ISU) Configuration Table

To enter ISU mode: Press and hold Menu and + simultaneously for 5 seconds until the advanced configuration screen displays.

ISU #Setting NameDefaultAvailable Options & Descriptions
120Schedule Type00 = Non-Programmable; 2 = 5-2 Day; 3 = 5-1-1 Day; 4 = 7-Day Programmable
200System Type11 = Conventional 1H/1C; 2 = Conventional Multi-stage; 3 = Heat Pump
205Heating Equipment11 = Standard Efficiency Gas; 2 = High Efficiency Gas (90%+); 3 = Electric Forced Air; 4 = Hot Water Fan Coil
218Reversing Valve (O/B)00 = O (Reversing valve energized in Cool - Carrier/Trane/Lennox); 1 = B (Energized in Heat - Rheem/Ruud)
220Cool Stages10 = None; 1 = 1 Cool Stage; 2 = 2 Cool Stages
221Heat Stages10 = None; 1 = 1 Heat Stage; 2 = 2 Heat Stages (Conventional)
300System Changeover00 = Manual (User selects Heat or Cool); 1 = Auto Changeover
387Compressor Off Time50 = None; 1 to 5 Minutes (Short-cycle protection delay)
425Temp Display Units00 = Fahrenheit (°F); 1 = Celsius (°C)
430Temp Display Offset0-3°F to +3°F (Calibrates internal temperature sensor)
Embedded Manual Viewer: TH6220U2000 / TH6320WF2003 Open Original PDF

Troubleshooting & System Diagnostics

Honeywell T6 Pro Alert & Error Code Matrix

Alert CodeMeaningCorrective Action
Alert 170Internal Memory ErrorCycle power at circuit breaker. If persistent, replace thermostat unit.
Alert 171Indoor Temp Sensor ErrorSensor open or shorted. Verify terminal pin contact with UWP baseplate.
Alert 173Humidity Sensor ErrorWi-Fi Lyric models only. Clean air vents on back of faceplate.
Alert 540 / 542Change Air Filter / Humidifier PadReplace HVAC filter and press Dismiss/Reset on the touch menu.

For additional programming details, explore the Honeywell Home Pro Series User Manual or download the official manufacturer document Resideo TechLit Doc #33-00181EFS.