DM80HS Furnace Manual

The DM80HS is a high-efficiency gas furnace with 80% AFUE rating, featuring variable-speed blower motor, electronic ignition, multi-speed operation, durable heat exchanger, integrated control board, safety shutoff switches, filter access, and compatibility with standard thermostat systems. Designed for residential heating applications with natural gas or propane capability. Below are key sections for safety, features, installation, setup, operation, and troubleshooting.

Features at a Glance

Key components: High-efficiency heat exchanger, variable-speed blower, electronic ignition system, integrated control board, filter compartment, gas valve, pressure switches, flame sensor.

Feature	Description
Heat Exchanger	Durable stainless steel construction
Blower Motor	Variable-speed ECM for efficient operation
Ignition System	Electronic hot surface ignition
Control Board	Integrated microprocessor control
Filter Access	Front-loading filter compartment
Gas Valve	Automatic gas flow regulation
Pressure Switches	Safety verification of venting
Flame Sensor	Monitors burner flame presence
Limit Switches	Prevents overheating
Drain Connection	Condensate removal system

Installation

Unpack and inspect contents. Position in approved location with proper clearances.

1. Gas connection: Use approved black iron pipe with pipe dope; pressure test for leaks.
2. Electrical connection: Connect to 120V AC power with proper grounding.
3. Vent system: Install PVC vent pipes per local codes with proper slope.
4. Drain line: Connect condensate drain to approved disposal.
5. Thermostat: Connect low-voltage wiring to control board.

WARNING! Gas appliances require professional installation. Ensure proper ventilation and combustion air supply.

First-Time Setup

Power on furnace; follow startup sequence.

1. System check: Control board performs self-diagnostic test.
2. Gas pressure: Verify correct manifold pressure per specifications.
3. Blower speed: Set appropriate CFM for heating application.
4. Thermostat configuration: Program heating cycles and temperature settings.
5. Safety verification: Test limit switches and pressure controls.

CAUTION! Only qualified technicians should perform initial setup and adjustment.

Specifications

• AFUE Rating: 80% Annual Fuel Utilization Efficiency
• Heating Capacity: 40,000-120,000 BTU/hr (multiple models)
• Blower Type: Variable-speed ECM
• Ignition: Electronic hot surface
• Gas Type: Natural gas or propane (conversion kit required)
• Electrical: 120V AC, 60Hz
• Venting: PVC pipe required
• Filter Size: Standard 16x25x1 inch
• Sound Level: Less than 65 dBA
• Warranty: 20-year heat exchanger, 5-year parts

Controls and Settings

Access control board via front panel. LED status lights indicate system operation.

Control Board: POWER, STATUS LED, DIP switches for blower speed, gas type selection, thermostat configuration.

Heating: Temperature rise adjustment, blower on/off delays, cycle rate. Safety: Limit switch settings, pressure switch verification, flame sensor monitoring. Diagnostic: Error code display, system status indicators, reset function.

Connecting Thermostat

Standard 24V thermostat connection with R, W, G, C terminals.

1. Turn off power to furnace before wiring.
2. Connect thermostat wires to control board terminals.
3. Match wire colors: R (24V), W (heat), G (fan), C (common).
4. Program thermostat for heating operation.

Tip: Use programmable thermostat for optimal efficiency and comfort.

Operation

Automatic heating cycle controlled by thermostat.

1. Call for heat: Thermostat signals control board.
2. Pre-purge: Blower runs to clear combustion chamber.
3. Ignition: Hot surface igniter glows, gas valve opens.
4. Flame verification: Flame sensor confirms ignition.
5. Heating: Burners operate, blower circulates warm air.
6. Shutdown: Thermostat satisfied, gas valve closes, blower continues for post-purge.

WARNING! Never block air vents or returns. Maintain proper airflow.

Safety Features

Multiple safety systems: Flame rollout switches, high limit switches, pressure switches, flame sensor, ignition control lockout.

Maintenance & Cleaning

Annual professional maintenance recommended. Monthly filter inspection/replacement.

1. Filter: Replace every 1-3 months depending on usage.
2. Burners: Clean annually to ensure proper combustion.
3. Flame sensor: Clean with emery cloth annually.
4. Drain system: Flush condensate trap and lines.
5. Blower: Vacuum and inspect for debris.

CAUTION! Turn off power and gas supply before performing any maintenance.

Regulatory Information

ANSI Z21.47: Certified for natural gas and propane operation. UL listed. Meets national fuel gas code requirements. For support, contact manufacturer technical service or authorized dealers. Installation must comply with local building codes and utility requirements.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Furnace won't start	Power, thermostat, safety switch	Check power supply; verify thermostat setting; reset door switch.
No heat	Gas supply, ignition, filter	Verify gas valve on; check for ignition; replace dirty filter.
Short cycling	Dirty filter, limit switch	Replace filter; check for blocked vents; verify limit operation.
Blower won't stop	Thermostat, control board	Check thermostat fan setting; inspect control board relay.
Error code flashing	System fault	Refer to error code chart in manual; reset if applicable.

Reset: Power cycle furnace; wait 5 minutes before restoring power.

Service: Contact qualified HVAC technician for all repairs.