Atwood Gas Furnace 85-IV Manual

The Atwood Gas Furnace 85-IV is a high-efficiency RV furnace designed for reliable heating in recreational vehicles. With 8,500 BTU output, electronic ignition, and multiple safety features, this furnace provides consistent warmth while maintaining fuel efficiency. Below are key sections covering safety, features, installation, operation, maintenance, and troubleshooting.

1. Features at a Glance 2. Installation 3. First-Time Setup 4. Specifications 5. Controls and Settings 6. Venting Requirements 7. Operation 8. Maintenance 9. Safety Features 10. Regulatory Information 11. Troubleshooting

Features at a Glance

Key components: Main burner assembly, blower motor, heat exchanger, electronic control board, thermostat, and safety switches.

Feature	Description
Heating Capacity	8,500 BTU/hour output
Ignition System	Electronic spark ignition
Fuel Type	Liquid propane (LP) gas
Airflow	Forced air with variable speed blower
Voltage	12V DC operation
Thermostat Control	Compatible with standard RV thermostats
Safety Features	Overheat protection, flame rollout switch
Venting	Direct vent system
Dimensions	Compact design for RV installation
Weight	Lightweight construction

Installation

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

Select installation location: Choose area with adequate clearance and proper venting access.
Mount furnace: Secure to floor or wall using provided brackets and hardware.
Connect gas supply: Use approved LP gas line with proper fittings.
Electrical connections: Connect 12V DC power following wiring diagram.
Install venting: Attach intake and exhaust vents according to specifications.
Connect thermostat: Wire to control unit for temperature regulation.

WARNING! Installation must be performed by qualified technician. Ensure proper ventilation and gas line integrity.

First-Time Setup

Complete installation checks before initial operation.

Gas system check: Verify no leaks using soap solution test.
Electrical verification: Confirm proper 12V DC connection and polarity.
Venting inspection: Ensure intake and exhaust are unobstructed.
Thermostat calibration: Set to desired temperature range.
Initial startup: Follow lighting procedure in operation section.

CAUTION! Test for gas leaks before operation. Ensure adequate fresh air supply.

Specifications

Model: 85-IV
Heating Capacity: 8,500 BTU/hour
Fuel Consumption: 0.10 gallons/hour (LP gas)
Electrical Requirements: 12V DC, 3.5 amps
Airflow: 55 CFM maximum
Dimensions: 17.5" H x 9.5" W x 21" D
Weight: 18 lbs
Venting: 2" diameter intake and exhaust
Sound Level: 55 dB maximum
Efficiency: 85% AFUE

Controls and Settings

Operation controlled via wall thermostat. Internal DIP switches for configuration.

Thermostat Settings: Heat/Off mode selection, temperature setpoint, fan control.

Internal Controls: Blower speed adjustment, ignition timing, safety lockout reset. DIP switch settings for altitude compensation, fan delay timing.

Venting Requirements

Direct vent system requires proper installation for safe operation.

Maintain minimum clearances: 12 inches from combustible materials.
Vent termination: Position to prevent blockage from snow or debris.
Vent pipe routing: Maintain downward slope away from furnace.
Sealing: Use high-temperature sealant on all joints.

Tip: Regularly inspect vent terminals for obstructions.

Operation

Standard operating sequence when thermostat calls for heat.

Initiation: Thermostat signals furnace control board.
Prepurging: Blower operates to clear combustion chamber.
Ignition: Spark igniter activates, gas valve opens.
Flame verification: Flame sensor confirms ignition.
Main operation: Burner operates, heat exchanger warms.
Air circulation: Blower distributes heated air.
Shutdown: Thermostat satisfied, gas valve closes, blower continues for cool-down.

WARNING! Do not operate without proper venting. Monitor for unusual odors or sounds.

Maintenance

Regular maintenance ensures optimal performance and safety.

Annual inspection by qualified technician
Clean burner assembly and orifice
Inspect heat exchanger for cracks or corrosion
Check and clean flame sensor
Lubricate blower motor if required
Verify safety switch operation
Clean air intake and exhaust vents

Safety Features

Multiple safety systems protect against hazardous conditions.

Overheat Protection: High-limit switch shuts off burner if temperatures exceed safe levels. Flame Rollout Switch: Detects improper burner flames and shuts down system. Pressure Switch: Ensures proper venting before ignition. Flame Sensor: Verifies burner ignition within trial period.

Regulatory Information

Certified to ANSI Z21.44 standards for recreational vehicle heaters. CSA International approved. Complies with UL and CSA safety requirements. Manufactured to meet RV industry specifications for reliability and durability.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Furnace won't start	Power supply, thermostat	Check 12V power, verify thermostat setting and wiring
No heat output	Gas supply, ignition	Verify LP gas supply, check for spark at igniter
Short cycling	Overheating, airflow	Check filters, clean heat exchanger, verify venting
Blower doesn't run	Motor, control board	Test blower motor, check control board output
Lockout condition	Safety switch, flame sense	Reset control board, clean flame sensor
Unusual odors	Dust, combustion	Clean burner assembly, verify proper combustion

Reset Procedure: Turn thermostat off for 5 minutes, then restart.

Service: Contact authorized Atwood service center for repairs.