DM 80 HS Furnace Manual

The DM 80 HS is a high-efficiency gas furnace with 80% AFUE rating, featuring variable-speed blower motor, electronic ignition, multi-speed operation, built-in diagnostic system, safety controls, 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, maintenance, and troubleshooting.

Features at a Glance

Key components: Heat exchanger, blower assembly, gas valve, electronic ignition, pressure switches, limit controls, diagnostic LED.

Feature	Description
Heat Exchanger	Stainless steel construction for durability and efficiency
Blower Motor	Variable-speed ECM motor for quiet operation
Electronic Ignition	Hot surface igniter for reliable startup
Gas Valve	Modulating valve for precise gas flow control
Pressure Switches	Safety switches for combustion air verification
Limit Controls	High-temperature safety cutoff
Diagnostic LED	Flash codes for system status and error reporting
Filter Access	Front-loading standard 1-inch filter
Venting	PVC pipe compatible for sidewall or roof venting
Electrical	120V AC, 60Hz standard connection

Installation Requirements

Professional installation recommended. Ensure proper clearances and venting.

1. Location: Install in dry, level area with adequate combustion air and service access.
2. Venting: Use approved PVC pipe; maintain proper slope and termination clearances.
3. Gas connection: Use black iron pipe with drip leg; pressure test for leaks.
4. Electrical: Connect to dedicated 120V circuit with proper grounding.
5. Ductwork: Ensure proper sizing and sealing for optimal airflow.

WARNING! Gas appliances can be hazardous; installation must comply with local codes and be performed by qualified technician.

First-Time Setup

After installation, perform initial startup procedure.

1. Verify all connections: Gas, electrical, venting, and ductwork.
2. Install clean air filter in proper orientation.
3. Open gas supply valve slowly; check for leaks with soap solution.
4. Power on furnace; set thermostat to heat mode above room temperature.
5. Observe ignition sequence and verify proper operation.
6. Check temperature rise against specifications.

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

Technical Specifications

• Model: DM 80 HS
• AFUE Rating: 80%
• Input BTU/H: 40,000 - 120,000 (depending on model)
• Output BTU/H: 32,000 - 96,000
• Gas Type: Natural gas or propane (conversion kit required)
• Electrical: 120V AC, 60Hz, 5-8 amps
• Blower Motor: Variable-speed ECM
• Venting: 2" PVC pipe minimum
• Filter Size: 16x25x1 inch standard
• Sound Level: < 65 dB
• Warranty: 20-year heat exchanger, 5-year parts

Controls and Operation

Integrated control board manages all furnace functions with diagnostic capabilities.

Thermostat Control: Compatible with most 24V thermostats; heat/cool/fan modes.

Operation Sequence: Thermostat call for heat → inducer motor starts → pressure switch verification → hot surface igniter heats → gas valve opens → flame sensor verification → blower starts after heat exchanger warm-up.

Diagnostic LED: Green = normal operation; Flash codes indicate specific faults (refer to troubleshooting chart).

Thermostat Connection

Standard 5-wire thermostat connection (R, W, Y, G, C).

1. Turn off power to furnace before connecting thermostat wires.
2. Match thermostat wires to corresponding terminals on control board.
3. R (24V power), W (Heat), Y (Cool), G (Fan), C (Common).
4. Secure connections and restore power.
5. Test all modes for proper operation.

Tip: Use programmable thermostat for optimal efficiency and comfort.

Maintenance Procedures

Regular maintenance ensures optimal performance and longevity.

1. Monthly: Check and replace air filter as needed.
2. Annual: Professional inspection and cleaning recommended.
3. Clean flame sensor with fine emery cloth.
4. Inspect heat exchanger for cracks or corrosion.
5. Check vent system for obstructions or damage.
6. Verify gas pressure and combustion analysis.
7. Lubricate blower motor if required (most are permanently lubricated).
8. Check electrical connections for tightness.

WARNING! Always disconnect power before performing any maintenance.

Safety Features

Multiple safety systems protect against hazardous conditions.

• Flame rollout switches: Shut off gas if flame escapes burners
• High limit switches: Prevent overheating
• Pressure switches: Verify proper venting before ignition
• Flame sensor: Confirms burner ignition; shuts off gas if no flame detected
• Gas valve: Automatic shutoff in case of system failure

Care & Cleaning

Keep furnace area clean and unobstructed.

Exterior: Wipe with dry cloth; avoid water or cleaning chemicals.

Interior: Professional cleaning only; do not attempt to clean heat exchanger or burners.

Filter: Replace every 1-3 months depending on usage and air quality.

CAUTION! Never operate without filter installed. Keep combustible materials away from furnace.

Regulatory Information

Certified to ANSI Z21.47 standards for gas-fired central furnaces. CSA International certified. Meets U.S. Department of Energy efficiency standards. For technical support, contact 1-800-555-HEAT or visit www.dmfurnace.com. Serial number located on rating plate inside furnace door.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Furnace won't start	Power, thermostat, door switch	Check circuit breaker; verify thermostat setting; ensure door properly closed.
No heat	Gas supply, ignition, filter	Verify gas valve open; check for flash codes; replace dirty filter.
Short cycling	Filter, limit switch, airflow	Clean/replace filter; check for blocked vents; verify proper airflow.
Blower won't stop	Thermostat, control board	Check thermostat fan setting; may indicate control board issue.
Unusual noises	Motor, blower wheel, ductwork	Inspect for loose components; clean blower wheel; check duct connections.
Error codes flashing	Various system faults	Count flashes and refer to diagnostic chart in service manual.

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

Service: 1-800-555-HEAT; www.dmfurnace.com