Atwood 8500 IV Series Furnace Manual

The Atwood 8500 IV Series is a high-efficiency RV furnace designed for reliable heating performance in recreational vehicles. This forced-air furnace features electronic ignition, variable-speed blower, multiple BTU output options, and safety shut-off systems. Below are key sections for 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. Operating Instructions 8. Maintenance Procedures 9. Safety Features 10. Regulatory Information 11. Troubleshooting

Features at a Glance

Key components: Electronic ignition system, variable-speed blower motor, heat exchanger, combustion chamber, sail switch, limit switch, thermostat control.

Feature	Description
Electronic Ignition	Pilotless ignition for reliable startup
Variable-Speed Blower	Adjustable airflow for optimal heating
Heat Exchanger	Stainless steel construction for durability
Combustion Chamber	Sealed combustion system
Sail Switch	Ensures proper airflow before ignition
Limit Switch	Safety shut-off if overheating occurs
Thermostat Control	Precise temperature regulation
Multiple BTU Options	Available in 16,000-30,000 BTU models
Forced Air System	Efficient heat distribution
Safety Shut-off	Automatic shutdown for safety conditions

Installation

Unpack and inspect all components. Ensure proper clearance and mounting surface.

Select location: Choose area with proper clearance and accessibility.
Mount furnace: Secure to floor or wall using provided brackets.
Connect ductwork: Attach supply and return air ducts securely.
Install venting: Connect exterior vent pipes according to specifications.
Electrical connections: Wire to 12V DC power source and thermostat.
Gas connection: Connect to LP gas supply with proper fittings.

WARNING! Installation must be performed by qualified technician. Follow all local codes and regulations.

First-Time Setup

Complete installation verification before initial operation.

Check all connections: Verify gas, electrical, and venting connections.
Test safety systems: Ensure limit switch and sail switch function properly.
Set thermostat: Program desired temperature settings.
Initial startup: Follow lighting procedure in operating section.
Monitor operation: Check for proper ignition and heat output.

CAUTION! Never bypass safety devices. Test carbon monoxide detector before use.

Specifications

Model Series: 8500 IV Series
BTU Output: 16,000 - 30,000 BTU/hr (varies by model)
Fuel Type: Liquid Propane (LP) Gas
Electrical: 12V DC Operation
Airflow: Variable-speed blower, CFM adjustable
Ignition: Electronic direct spark ignition
Efficiency: High-efficiency heat exchanger
Dimensions: Varies by model (check specific model label)
Weight: Approximately 15-25 lbs depending on model
Venting: Requires proper exterior venting system

Controls and Settings

Primary control through wall thermostat. Internal controls include limit switch, sail switch, gas valve, control board.

Thermostat Settings: Temperature setpoint, fan control (auto/on), system on/off.

Internal Controls: Limit switch (temperature safety), sail switch (airflow safety), gas valve (fuel control), control board (ignition sequence), blower speed adjustment (varies by model).

Venting Requirements

Proper venting is critical for safe operation and efficiency.

Exterior vent location: Must be clear of obstructions and weather elements.
Vent pipe size: Use manufacturer-specified diameter and material.
Clearance: Maintain proper clearance from combustible materials.
Vent termination: Ensure proper exterior termination cap installation.

Tip: Regular inspection of vent system prevents blockage and ensures safe operation.

Operating Instructions

Normal operation sequence: Thermostat call → blower start → sail switch activation → ignition sequence → gas valve open → burner ignition → heat production.

Set thermostat to desired temperature above current room temperature.
Listen for blower motor starting (pre-purge cycle).
Ignition sequence begins (spark ignition audible).
Burner lights (visible through sight glass if equipped).
Heating cycle continues until thermostat satisfied.
Shutdown sequence: Gas valve closes → blower continues (post-purge) → system off.

WARNING! Never operate with cover removed. Monitor for unusual sounds or odors.

Maintenance Procedures

Regular maintenance ensures optimal performance and safety.

Annual inspection by qualified technician
Clean air filters monthly during heating season
Inspect vent system for blockages
Check burner and heat exchanger for corrosion
Verify proper gas pressure
Test safety controls operation
Lubricate blower motor if required (specific models)

CAUTION! Always disconnect power before performing maintenance.

Safety Features

Multiple safety systems protect against hazardous conditions.

Safety Feature	Function
Limit Switch	Shuts off burner if overheating detected
Sail Switch	Prevents ignition if inadequate airflow
Gas Valve	Automatic shut-off if flame not detected
Overcurrent Protection	Circuit protection for electrical components
Vent Safety	Prevents operation if vent blocked

Regulatory Information

Complies with ANSI Z21.44 standards for recreational vehicle heaters. CSA certified for safety and performance. Manufactured to meet RV industry specifications. For technical support, contact Atwood Customer Service at 1-800-555-ATWOOD or visit www.atwoodmobile.com.

Troubleshooting

Symptom	Possible Cause	Corrective Action
No ignition	Power, gas supply, ignition	Check 12V power, gas valve, ignition system
Blower runs but no heat	Gas supply, ignition	Verify gas supply, check ignition sequence
Short cycling	Airflow, thermostat	Clean filter, check ductwork, verify thermostat
Unusual odors	Dust, combustion	Clean system, check combustion air
No blower operation	Power, motor, switch	Check power, blower motor, sail switch

Reset: Turn thermostat off, wait 5 minutes, restart.

Service: 1-800-555-ATWOOD; www.atwoodmobile.com