DC90 Ultra High Efficiency Furnace Manual

The DC90 Ultra High Efficiency Furnace is a high-performance gas furnace with 90% AFUE rating, variable-speed blower motor, two-stage gas valve, electronic ignition system, durable heat exchanger, smart thermostat compatibility, built-in diagnostic system, safety controls, and energy-efficient operation. Suitable for residential heating applications with natural gas or propane capability. Below are key sections for safety, features, installation, setup, operation, maintenance, and troubleshooting.

1. Features at a Glance 2. Installation 3. First-Time Setup 4. Specifications 5. Controls and Settings 6. Connecting Thermostat 7. Operating Modes 8. Maintenance Procedures 9. Safety Features 10. Regulatory Information 11. Troubleshooting

Features at a Glance

Key components: Two-stage gas valve, variable-speed ECM blower motor, aluminized steel heat exchanger, electronic ignition, pressure switches, flame sensor, diagnostic LED, filter access door.

Feature	Description
AFUE Rating	90% Annual Fuel Utilization Efficiency
Gas Valve	Two-stage operation for efficient heating
Blower Motor	Variable-speed ECM for quiet operation
Heat Exchanger	Aluminized steel construction
Ignition System	Electronic hot surface ignition
Diagnostic LED	Flash codes for troubleshooting
Filter Access	Front-loading filter compartment
Pressure Switches	Safety verification of vent operation
Flame Sensor	Monitors burner operation
Thermostat Compatibility	Works with most 24V thermostats

Installation

Unpack and inspect all components. Ensure proper clearances and venting.

Position furnace: Place on stable, level surface with proper clearances.
Install venting: Use approved PVC pipe for intake and exhaust.
Connect gas line: Use black iron pipe with proper sealant.
Electrical connections: Connect 120V power and thermostat wiring.
Install condensate drain: Route to proper drainage location.

WARNING! Installation must be performed by qualified HVAC technician. Gas leaks can cause explosion or fire.

First-Time Setup

Power on furnace; follow startup procedure.

Verify gas supply: Ensure gas valve is open and connections are tight.
Check electrical: Confirm 120V power and proper thermostat wiring.
Startup sequence: System will run self-check and begin operation.
Adjust blower speed: Set appropriate CFM for heating application.
Test operation: Verify proper ignition and heating cycle.

CAUTION! Never bypass safety controls. Ensure proper ventilation during operation.

Specifications

AFUE Rating: 90%
Input BTU/H: 40,000 - 120,000 (varies by model)
Stages: Two-stage heating operation
Blower Type: Variable-speed ECM
Ignition: Hot surface electronic ignition
Gas Type: Natural gas or propane (conversion kit required)
Voltage: 120V AC, 60Hz
Filter Size: 16x25x1 inch (standard)
Venting: PVC pipe (2-3 inch diameter)
Warranty: 20-year heat exchanger, 5-year parts

Controls and Settings

Access control board via front panel. Diagnostic LED provides status codes.

Control Board: POWER switch, FUSE, THERMOSTAT terminals, GAS VALVE terminals, PRESSURE SWITCH terminals.

Operating Modes: HEAT, OFF, FAN ON. Blower Settings: Adjustable delay timers for fan on/off. Diagnostic Codes: LED flash patterns indicate specific faults. Gas Valve: Two-stage operation for high/low fire modes.

Connecting Thermostat

Compatible with most 24V thermostats. Standard 5-wire connection.

Turn off power to furnace before wiring.
Connect thermostat wires: R (power), W (heat), G (fan), Y (cool), C (common).
Secure connections and replace access panel.
Restore power and test thermostat operation.

Tip: Use programmable thermostat for maximum energy efficiency.

Operating Modes

Three main operating modes controlled by thermostat.

Heat Mode: Furnace responds to heat calls from thermostat.
Fan Mode: Continuous fan operation for air circulation.
Off Mode: Complete system shutdown.
Two-Stage Operation: Low fire for mild days, high fire for cold days.
Variable Blower: Automatically adjusts airflow for optimal comfort.

WARNING! Do not operate furnace without proper venting and air filters installed.

Maintenance Procedures

Regular maintenance ensures optimal performance and longevity.

Monthly: Check and replace air filter as needed.
Annual: Professional inspection and cleaning.
Seasonal: Verify proper venting and drainage.
As needed: Clean flame sensor and inspect heat exchanger.

CAUTION! Always turn off power and gas supply before performing maintenance.

Safety Features

Multiple safety systems protect against hazardous conditions.

Safety Feature	Function
Flame Rollout Switch	Detects improper burner flames
High Limit Switch	Prevents overheating
Pressure Switches	Verify proper vent operation
Flame Sensor	Confirms burner ignition
Gas Valve	Automatic shutoff if flame not detected

Regulatory Information

UL certified for safety standards. ANSI Z21.47 compliant for gas appliances. Meets DOE energy efficiency requirements. Manufactured to ISO 9001 quality standards. For technical support, contact 1-800-HEATING or visit www.dc90furnace.com. Serial number located on rating plate inside unit.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Furnace won't start	Power, thermostat, door switch	Check circuit breaker, thermostat settings, door switch engagement
No heat	Gas supply, ignition	Verify gas valve open, check for ignition attempts
Blower won't run	Motor, capacitor, wiring	Check blower motor, capacitor, electrical connections
Short cycling	Filter, limit switch	Replace dirty filter, check high limit switch
Lockout mode	Safety device tripped	Reset power, check diagnostic LED for fault code

Reset Procedure: Turn power off for 30 seconds, then restore.

Service: 1-800-HEATING; www.dc90furnace.com