Honeywell Furnace Control Board Manual

The Honeywell Furnace Control Board is a sophisticated electronic control system designed for residential and commercial furnace applications. It features integrated safety controls, diagnostic LED indicators, multi-stage heating capability, blower motor control, flame sensor monitoring, and compatibility with various thermostat systems. Below are key sections covering installation, operation, troubleshooting, and maintenance procedures.

1. Features at a Glance 2. Installation Guidelines 3. Wiring Configuration 4. Technical Specifications 5. Control Board Operation 6. Diagnostic Indicators 7. Safety Features 8. Maintenance Procedures 9. Regulatory Compliance 10. Troubleshooting Guide

Features at a Glance

Key components: Main control processor, LED status indicators, terminal blocks, fuse protection, transformer connections, gas valve control, inducer motor control, and blower motor outputs.

Feature	Description
LED Status Indicators	Provides visual diagnostic codes for troubleshooting
Multi-stage Heating	Supports single and two-stage furnace operation
Blower Control	Variable speed blower motor management
Flame Sensor Input	Monitors flame presence for safety shutdown
Pressure Switch Inputs	Verifies proper venting operation
Thermostat Connections	Compatible with conventional and smart thermostats
Limit Circuit Protection	Prevents overheating conditions
Fuse Protection	3A fuse for circuit protection
Transformer Input	24VAC power input connection
Gas Valve Control	Manages gas valve operation sequences

Installation Guidelines

Proper installation ensures safe and efficient furnace operation. Follow all local codes and manufacturer specifications.

Power Disconnect: Turn off electrical power and gas supply before installation.
Board Mounting: Secure control board using provided mounting holes and standoffs.
Wiring Connection: Route wires through appropriate strain relief and connect to proper terminals.
Gas Valve Connection: Connect gas valve control wires to designated terminals.
Transformer Connection: Connect 24VAC transformer leads to proper input terminals.

WARNING! Only qualified HVAC technicians should install or service this control board. Incorrect installation can cause fire, explosion, or carbon monoxide poisoning.

Wiring Configuration

Refer to wiring diagram included with control board for specific terminal assignments.

Thermostat Connections: R (24V), W/W1/W2 (Heat), G (Fan), C (Common)
Blower Motor: Connect to appropriate speed taps for heating and cooling operation
Inducer Motor: Connect inducer relay output to inducer motor
Pressure Switches: Connect normally open pressure switch contacts
Flame Sensor: Connect micro-amp flame sensor input
Gas Valve: Connect gas valve output terminals

CAUTION! Verify all connections are secure and properly insulated. Use wire nuts or terminal blocks as required.

Technical Specifications

Input Voltage: 24VAC, 60Hz
Maximum Current: 3A fused protection
Operating Temperature: -40°F to 150°F (-40°C to 65°C)
Humidity Range: 5% to 95% RH non-condensing
Flame Sensor: 0.5 to 10 microamps DC
Pressure Switch: Normally open, 24VAC rated
Gas Valve Output: 24VAC, 0.5A maximum
Blower Control: Multi-speed tap connections
Certifications: UL, CSA, ANSI Z21.47

Control Board Operation

The control board follows a specific ignition sequence for safe furnace operation.

Normal Heating Sequence: Thermostat call for heat → Inducer motor starts → Pressure switch verification → Hot surface igniter heats → Gas valve opens → Flame detection → Blower motor starts → Continuous operation until thermostat satisfied

LED Indicators: Solid green = normal operation, Flashing codes = diagnostic information, No light = no power or board failure.

Diagnostic Indicators

LED flash patterns indicate specific operational status and fault conditions.

Flash Pattern	Description	Action Required
1 Flash	Pressure switch stuck open	Check inducer, venting, pressure switch
2 Flashes	Pressure switch stuck closed	Replace pressure switch
3 Flashes	Ignition failure	Check gas supply, igniter, flame sensor
4 Flashes	Limit circuit lockout	Check airflow, filters, limit switches
5 Flashes	Flame sense failure	Clean flame sensor, check grounding
6 Flashes	Rollout switch open	Check heat exchanger, venting
7 Flashes	Gas valve circuit fault	Check gas valve wiring and voltage

Safety Features

Multiple safety systems protect against hazardous conditions.

Flame Rollout Protection: Rollout switches detect improper combustion
High Limit Protection: Temperature limits prevent overheating
Pressure Switch Monitoring: Ensures proper venting before ignition
Flame Detection: Confirms flame presence within trial for ignition period
Fuse Protection: Prevents electrical overload damage
Lockout Protection: Prevents continuous ignition attempts

WARNING! Never bypass safety devices. Replace faulty components immediately.

Maintenance Procedures

Regular maintenance ensures optimal performance and longevity.

Annual Inspection: Check all electrical connections for tightness
Flame Sensor Cleaning: Clean with fine emery cloth annually
Filter Replacement: Replace air filters monthly during heating season
Venting Inspection: Check vent pipes for obstructions or damage
Electrical Testing: Verify proper voltages at all terminals
Gas Pressure Check: Verify correct manifold gas pressure

CAUTION! Always disconnect power before performing maintenance.

Regulatory Compliance

This control board complies with UL Standard 60730-1, ANSI Z21.47, and CSA C22.2 No. 199. Installation must comply with National Fuel Gas Code (NFPA 54), National Electrical Code (NFPA 70), and all local building codes. For technical support, contact Honeywell Customer Support at 1-800-468-1502 or visit www.honeywell.com/homes.

Troubleshooting Guide

Symptom	Possible Cause	Corrective Action
No heat	Power loss, thermostat issue	Check circuit breaker, thermostat settings, transformer
Furnace short cycles	Dirty filter, blocked vent	Replace filter, check venting, verify airflow
Blower won't start	Motor failure, capacitor issue	Check blower motor, capacitor, control board output
Igniter doesn't glow	Failed igniter, wiring issue	Test igniter continuity, check wiring connections
Gas valve doesn't open	Valve failure, pressure switch	Verify 24V at valve, check pressure switch operation
LED flashing error code	Specific fault condition	Refer to diagnostic chart for specific flash pattern

Reset Procedure: Turn power off for 30 seconds, then restore power to reset control board.

Technical Support: 1-800-468-1502; www.honeywell.com/homes