RV Furnace Exhaust Extension: Safe Installation, Maintenance, and Best Practices

RV owners often consider an RV furnace exhaust extension to direct combustion gases away from entryways, slide-outs, and outdoor living spaces; this article explains why extensions are used, how to choose and install them safely, and how to maintain compliance with manufacturer and safety guidelines.

Topic	Summary
Purpose	Redirect furnace exhaust for safety and comfort
Materials	Stainless steel, aluminum, or factory-approved kits
Key Concerns	Carbon monoxide, backpressure, warranty and code compliance

Why RV Furnace Exhaust Extensions Are Used

An RV furnace exhaust extension is commonly installed to move exhaust outlets away from doors, windows, slide rooms, awnings, or areas where people congregate. Extensions can reduce odors entering the coach and minimize soot deposits on exterior walls and awnings.

Extensions may also be sought when aftermarket accessories, rooftop equipment, or parked configurations change how exhaust disperses. However, any modification affects system performance and safety, so understanding implications is critical.

How RV Furnace Exhaust Systems Work

RV furnaces burn propane or natural gas and expel combustion byproducts—primarily carbon dioxide, water vapor, and small amounts of carbon monoxide—through an exhaust vent. Many modern RV furnaces use a sealed combustion chamber and a flue with a draft inducer; proper drafting is essential to avoid exhaust recirculation.

Exhaust extensions alter the terminal geometry and can affect draft, backpressure, and condensation. Maintaining manufacturer-specified clearances and vent configurations preserves efficiency and reduces the risk of dangerous combustion byproducts entering the living space.

Types Of Exhaust Extensions And Materials

Common options include short rigid extensions, flexible stainless piping, and factory-designed extension kits. Materials typically used are stainless steel for corrosion resistance and aluminum for lightweight applications. Flexible stainless flex offers some routing convenience but can increase resistance and collect condensation.

• Factory Extension Kits: Designed by the furnace manufacturer to maintain performance and warranty.
• Rigid Stainless or Powder-Coated Shells: Durable and low-resistance but require precise alignment.
• Flexible Stainless Piping: Easier to route in tight spaces; may increase turbulence.

Safety And Regulatory Considerations

An RV furnace exhaust extension must not compromise safety. Federal and state regulations may apply, and manufacturers often provide clear instructions and restrictions. Installation that voids the furnace warranty or violates local codes can expose owners to hazards and liability.

Key safety considerations: maintain required clearances from openings, avoid routing near air intakes or propane tanks, ensure no blockage occurs, and preserve proper draft to prevent carbon monoxide intrusion.

Manufacturer Guidance And Warranty Impacts

Most furnace manufacturers specify approved venting components and maximum extension lengths. Using non-approved parts or exceeding specified lengths can void the warranty and increase risk. Before any modification, consult the furnace manual or manufacturer technical support.

Dealerships and certified RV technicians can confirm whether a particular extension is permitted and recommend factory-approved parts. Documenting approvals in writing helps if warranty or safety disputes arise.

Assessing Whether An Extension Is Needed

Before installing an exhaust extension, evaluate the problem and alternatives. Simple solutions sometimes work better than modifying the flue: repositioning furniture, adjusting awnings, moving the grill area, or redirecting window ventilation may eliminate the issue with no risk to the furnace system.

If exhaust is entering the RV, check seals around doors and windows, inspect the furnace and vent for blockage, and confirm the unit is operating correctly. Use a carbon monoxide detector inside the coach to ensure safety before making changes.

Installation Best Practices

When an extension is approved, follow these best practices: use manufacturer-specified parts, maintain straight sections where possible, minimize length, avoid downward slopes that trap condensate, and secure joints with appropriate clamps or fasteners.

• Keep Extensions Short: Longer runs increase backpressure and reduce draft efficiency.
• Maintain Smooth Flow: Avoid sharp bends and crushes that cause turbulence.
• Seal Joints Properly: Use high-temperature gaskets or approved sealants when required.
• Secure Mounting: Prevent chafing and movement during travel.

Common Installation Configurations

Typical configurations include a short vertical riser to lift the terminal above a roofline, a horizontal extension to clear a slide-out, or a curved outlet to direct exhaust away from an awning. Each configuration must preserve draft and not place the terminal where exhaust can re-enter doors or vents.

Avoid routing exhaust under awnings or along awning arms, as heat and soot can damage fabrics and hardware. If the goal is to direct exhaust up and away, a short vertical riser within manufacturer limits is usually preferable.

Tools And Supplies Needed

Common tools include a drill, screwdriver, stainless clamps, sheet-metal screws, a tape measure, and a level. Supplies may include approved vent pipe, high-temperature sealant, flashing (for roof penetrations), and support brackets. For roof-mounted work, use fall protection and follow RV roof safety practices.

Testing And Verification After Installation

After installing an exhaust extension, test the furnace in several conditions: steady-state heat, multiple start-stop cycles, and with doors and windows open to assess exhaust dispersion. Use a combustion analyzer if available to verify draft and check for elevated carbon monoxide levels near the intake and living areas.

Install or verify functioning carbon monoxide detectors in sleeping and living areas. Regularly inspect the external terminal while the furnace runs to confirm visible drafts and absence of leaks or soot buildup at unintended locations.

Maintenance And Inspection Schedule

Inspect the exhaust extension seasonally and after long trips. Check for loose clamps, corrosion, dents, or crushed sections. Clean soot or insect nests from terminals and confirm screens or guards are intact. Replace damaged segments promptly to avoid performance loss.

Also inspect interior furnace components—burner, heat exchanger, and flue passages—per the manufacturer’s maintenance schedule. Routine maintenance reduces the chance of incomplete combustion and exhaust-related problems.

Common Problems And Troubleshooting

Frequent issues include increased soot, decreased furnace performance, condensation pooling, or exhaust odor in the coach. Troubleshooting steps include removing the extension temporarily to confirm whether problems are extension-related and checking for blocked or crushed sections.

If condensation occurs, ensure the extension is sloped to drain condensate back toward the furnace or provide a condensate trap if applicable. Persistent odors or CO detection requires immediate shutdown of the furnace and professional inspection.

Professional Help And Certified Technicians

When in doubt, consult a certified RV technician or the furnace manufacturer. Certified technicians can assess flue performance, measure draft, recommend approved kits, and perform safe installations. Unlicensed modifications that affect combustion can create risks not easily visible to untrained owners.

Tips For Buying An Extension Kit

Look for kits that explicitly list compatibility with the furnace model, include mounting hardware, and provide installation instructions. Prefer stainless components and kits that maintain the original terminal geometry. Read reviews from other RV owners and check with the furnace manufacturer for recommended suppliers.

• Check Model Compatibility
• Confirm Materials And Finish
• Verify Included Hardware And Instructions
• Ask For Technical Support Availability

Alternatives To Exhaust Extensions

Alternatives include relocating outdoor living areas, adding windbreaks, adjusting the RV orientation when parked, or installing intake deflectors that prevent recirculation. In some cases, upgrading to a newer furnace with a different vent orientation can resolve ongoing issues.

For temporary needs, portable vents or removable deflectors can redirect exhaust without permanent modification to the furnace system.

Key Safety Reminders

Always prioritize carbon monoxide safety: never leave a furnace running without working CO detectors, never alter vents without manufacturer approval, and avoid routing exhaust where it can accumulate near openings or occupants. Document approvals and keep maintenance records for safety and warranty purposes.

Useful Resources And References

Owners should consult the furnace owner’s manual, RV manufacturer documentation, and websites of reputable furnace makers for model-specific guidance. Industry groups and RV service centers often publish best-practice guides and safety bulletins.

Useful resources include furnace manufacturer technical support, RVIA (Recreation Vehicle Industry Association) guidelines, and certified RV service centers.

Summary Of Best Practices

Action	Recommendation
Before Modifying	Consult manufacturer and consider alternatives
Material Choice	Prefer stainless steel and factory-approved kits
Installation	Keep runs short, minimize bends, secure joints
Safety	Maintain clearances, use CO detectors, professional inspection

This article aims to equip RV owners with practical, safety-focused knowledge about RV furnace exhaust extensions. Proper assessment, adherence to manufacturer guidance, and professional assistance where needed will help ensure safe and effective solutions without compromising warranty or occupant safety.