Atwood 8535 RV Furnace Repair Manual

The Atwood 8535 is a high-efficiency RV furnace designed for recreational vehicles, featuring a compact design, forced-air heating system, electronic ignition, and multiple safety features. This manual covers installation, operation, troubleshooting, maintenance, and repair procedures for the 8535 series furnace. Below are key sections for safety precautions, technical specifications, installation guidelines, operation instructions, maintenance procedures, and troubleshooting guides.

1. Features at a Glance 2. Installation Guidelines 3. Operation Instructions 4. Technical Specifications 5. Controls and Components 6. Maintenance Procedures 7. Troubleshooting Guide 8. Safety Features 9. Parts Replacement 10. Regulatory Information 11. Service Contacts

Features at a Glance

Key components: Main burner assembly, blower motor, sail switch, limit switch, electronic control board, gas valve, thermostat, and exhaust system.

FeatureDescription
Heating Capacity25,000 BTU/hour output
Ignition SystemElectronic spark ignition
Fuel TypeLiquid propane (LP) gas
AirflowForced-air circulation system
Voltage12V DC operation
Thermostat ControlElectronic thermostat with temperature settings
Safety FeaturesOverheat protection, flame failure detection
Exhaust SystemSealed combustion chamber
DimensionsCompact design for RV installation
WeightApproximately 15 lbs

Installation Guidelines

Proper installation is critical for safe and efficient operation. Follow all local codes and RV manufacturer specifications.

  1. Location Selection: Choose well-ventilated area with proper clearance from combustible materials.
  2. Mounting: Secure furnace to RV frame using provided mounting brackets.
  3. Gas Line Connection: Use approved LP gas lines and fittings; pressure test for leaks.
  4. Electrical Connection: Connect to 12V DC power supply with proper fuse protection.
  5. Vent System: Install intake and exhaust vents according to manufacturer specifications.
  6. Ductwork: Connect heating ducts ensuring proper airflow distribution.

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

Operation Instructions

Operating the Atwood 8535 furnace requires proper thermostat settings and system checks.

  1. Power On: Ensure 12V power is available and thermostat is set to desired temperature.
  2. Start Sequence: Thermostat calls for heat, blower starts, ignition sequence begins.
  3. Ignition: Electronic spark ignites gas, flame sensor confirms ignition.
  4. Heating Cycle: Burner operates until thermostat satisfaction.
  5. Shutdown: Burner turns off, blower continues for cool-down period.

CAUTION! Never operate furnace with cover removed. Ensure proper ventilation during operation.

Technical Specifications

Controls and Components

Understanding furnace components is essential for proper operation and troubleshooting.

Main Components: Control board, gas valve, blower motor, sail switch, limit switch, igniter, flame sensor, thermostat.

Control Board: Manages ignition sequence, monitors safety switches, controls blower operation. Gas Valve: Regulates gas flow to burner. Blower Motor: Circulates heated air through duct system. Sail Switch: Confirms adequate airflow before ignition. Limit Switch: Prevents overheating by shutting off gas if temperature exceeds safe limits. Igniter: Creates spark for gas ignition. Flame Sensor: Detects presence of flame. Thermostat: User interface for temperature control.

Maintenance Procedures

Regular maintenance ensures optimal performance and extends furnace lifespan.

  1. Annual Inspection: Check all components before heating season.
  2. Cleaning: Remove dust and debris from burner assembly and heat exchanger.
  3. Gas System: Inspect gas lines for leaks, clean orifice.
  4. Electrical: Check wiring connections, test control board operation.
  5. Vent System: Ensure intake and exhaust vents are clear of obstructions.
  6. Blower: Clean blower wheel and housing, lubricate motor if required.

Tip: Keep maintenance records for warranty and service purposes.

Troubleshooting Guide

Common issues and solutions for Atwood 8535 furnace operation.

SymptomPossible CauseCorrective Action
Furnace won't startPower loss, thermostat issueCheck 12V power, verify thermostat settings, inspect fuse.
No heat outputGas supply, ignition failureCheck LP tank level, verify gas valve operation, inspect igniter.
Blower runs but no heatIgnition system failureCheck spark igniter, flame sensor, gas valve operation.
Furnace cycles on/off rapidlyOverheating, airflow restrictionClean heat exchanger, check ductwork, verify blower operation.
Unusual noisesBlower issues, loose componentsInspect blower wheel, tighten mounting hardware, check for obstructions.
Gas odorGas leakImmediately shut off gas supply, ventilate area, check for leaks.

Safety Features

The Atwood 8535 incorporates multiple safety systems to prevent hazardous conditions.

WARNING! Never bypass safety devices. Tampering with safety systems creates serious hazards.

Parts Replacement

Authorized replacement parts ensure proper fit and performance.

  1. Control Board: Part # 33120 - Electronic control module
  2. Gas Valve: Part # 33155 - LP gas control valve
  3. Blower Motor: Part # 33180 - 12V DC blower assembly
  4. Igniter: Part # 33195 - Electronic spark igniter
  5. Flame Sensor: Part # 33210 - Flame detection sensor
  6. Thermostat: Part # 33235 - Electronic temperature control
  7. Limit Switch: Part # 33260 - Overheat protection switch
  8. Sail Switch: Part # 33285 - Airflow detection switch

Note: Use only genuine Atwood replacement parts for safety and warranty compliance.

Regulatory Information

This furnace complies with ANSI Z21.44 standards for recreational vehicle heaters. Certified by CSA International for North American use. Installation must comply with NFPA 1192 Standard for Recreational Vehicles and all local codes. Manufactured by Atwood Mobile Products. Copyright protection applies to all technical documentation.

Service Contacts

For technical support, parts ordering, or authorized service:

Emergency Service: For gas leaks or immediate safety concerns, contact local emergency services and qualified HVAC technician.

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