5 Best Furnaces For High Altitude RVs That Support Self-Reliance

You wake up at 3 AM to a biting cold inside your RV, parked somewhere beautiful above 9,000 feet. The furnace fan is running, but there’s no heat. That familiar click-click-click of the igniter is followed by silence, a cycle that repeats until the system gives up, leaving you to shiver in your sleeping bag. This isn’t just an inconvenience; it’s a critical failure that can cut a trip short and put you in a dangerous situation. Choosing a furnace that works reliably in thin mountain air is fundamental to true self-reliance on the road.

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Why Standard RV Furnaces Fail at Altitude

Most standard RV furnaces are designed and calibrated for sea level. As you climb in elevation, the air gets thinner, meaning there’s less oxygen per cubic foot. Your furnace, however, doesn’t know this; it continues to inject the same amount of propane into the combustion chamber, creating a fuel-rich mixture.

This imbalance leads to a cascade of problems. The flame burns dirty and yellow instead of clean and blue, producing soot that clogs the burner and heat exchanger. More critically, this incomplete combustion generates significantly higher levels of carbon monoxide (CO), a colorless, odorless gas that is extremely dangerous. The furnace’s own safety sensors will often detect this poor combustion and shut the unit down to prevent a hazardous condition, which is exactly why it fails to light or stay lit when you need it most.

Propex HS2000: Quiet, Efficient Propane Heat

The Propex HS2000 is a legend in the van life and overlanding world for good reason. It’s a compact, propane-fired forced-air heater that sips fuel and runs so quietly you’ll barely notice it. Unlike the roaring jet engine sound of a traditional RV furnace, the Propex delivers a gentle, consistent warmth.

Its reliability at altitude comes from its efficient, sealed combustion design. The unit pulls outside air for combustion and exhausts directly back outside, completely isolating the process from your living space. While Propex doesn’t officially market a specific high-altitude model, their robust engineering has proven highly tolerant of thin air, with countless users running them successfully up to 10,000 feet and beyond with little to no issue. It’s an ideal choice for smaller, well-insulated rigs where its 6,500 BTU output is more than sufficient.

The main tradeoff is its lower heat output compared to larger factory furnaces. In a big, drafty fifth-wheel on a zero-degree night, it might struggle to keep up. But for a van, truck camper, or small travel trailer, its efficiency and quiet operation make it a top contender for off-grid mountain living.

Webasto Air Top 2000 STC: Diesel Powerhouse

If your rig runs on diesel, the Webasto Air Top 2000 STC is the gold standard. These heaters are workhorses, trusted in long-haul trucking and marine applications for decades. They are incredibly efficient, using just a tiny amount of diesel to produce a powerful 7,000 BTUs of dry heat.

The Webasto’s key feature for mountain travel is its built-in altitude sensor. As you climb, the unit automatically adjusts the fuel pump’s metering to lean out the mixture, ensuring clean and efficient combustion up to 7,200 feet. For even higher elevations, many users install a high-altitude kit or a manual rheostat to fine-tune the fuel delivery, enabling reliable operation well over 10,000 feet.

The biggest advantage here is fuel logistics. By tapping directly into your vehicle’s main diesel tank, you eliminate the need to carry and manage separate propane tanks for heat. This massively simplifies long-term travel and is a huge win for self-reliance. For gasoline-powered RVs, Webasto offers a nearly identical gasoline version, providing the same benefits.

Suburban SF-30FQ: A High-Altitude Classic

Many RVs come equipped with a Suburban furnace right from the factory. While the standard models will struggle at altitude, they shouldn’t be dismissed outright. Suburban is one of the few traditional RV furnace manufacturers that offers an official high-altitude derating kit.

This kit is simple in principle: it involves replacing the standard gas valve orifice with a smaller one. This reduces the amount of propane injected, leaning out the fuel/air mixture to compensate for the lack of oxygen at elevation. This is a manual conversion, meaning you’re meant to install it when you plan to spend time consistently above 4,500 feet.

The SF-30FQ is a powerful, ducted furnace that can heat a large rig effectively. The downside is that it’s loud and consumes a significant amount of 12-volt power to run its large blower fan. For the RVer who already has this unit installed, buying the $20 orifice kit is a far more economical solution than replacing the entire system. It’s a practical, if less elegant, way to adapt a common furnace for mountain adventures.

Dickinson P9000: Off-Grid Propane Fireplace

For a completely different approach, consider the Dickinson P9000. This isn’t a forced-air furnace; it’s a small, direct-vent propane fireplace that provides quiet, radiant heat. Its charm is undeniable, with a small window showing a real, flickering flame that adds a cozy ambiance to any small space.

Its primary advantage for self-reliance is its power consumption: zero. The P9000 operates entirely without electricity, making it a perfect solution for off-grid boondocking where battery conservation is paramount. It has a small, optional 12-volt fan to help circulate air, but the unit radiates heat beautifully without it. The sealed combustion chamber draws air from and vents to the outside through a small chimney, making it perfectly safe for small interiors.

Because of its simple, natural draft design, the Dickinson is very forgiving at altitude. The visible flame also serves as an excellent, real-time indicator of combustion quality. If you see it getting sooty or yellow, you know you need to adjust the air intake or clean the burner. It’s a simple, reliable, and elegant heating solution for those who prioritize silence and energy independence over powerful, ducted airflow.

Truma Combi Eco: Premium All-in-One System

The Truma Combi is the premium, all-in-one solution for heat and hot water. This German-engineered unit combines a furnace and a water heater into a single, highly efficient appliance, saving valuable space and weight in your rig. It’s known for being incredibly quiet and for its precise temperature control.

For high-altitude performance, the Truma Combi is a standout. It features an integrated electronic system that automatically detects changes in air pressure. When it senses you’re above 5,000 feet, it automatically adjusts the combustion fan’s speed to force more of the thin air into the burner. This ensures a perfect fuel/air mixture for clean, efficient heat at elevations where other furnaces fail.

The only significant drawback is the price. The Truma Combi is a substantial investment, often several times the cost of other heating options. However, for those building a high-end, four-season rig for serious travel, the performance, efficiency, and convenience of having a single, intelligent system for both heat and hot water are often worth the premium.

Key Factors: High Altitude Kits and Fuel Types

When choosing your heater, the decision often boils down to two key factors: how it handles altitude and what fuel it burns.

There are two primary methods for high-altitude compensation:

• Automatic Adjustment: Systems like the Webasto and Truma use sensors to detect air pressure and automatically adjust fuel delivery or fan speed. This is the most convenient and reliable method, but it comes at a higher price.
• Manual Conversion: Traditional furnaces like the Suburban can be adapted with a "derating kit," which involves physically swapping the gas orifice. This is inexpensive but requires manual intervention and is less precise. You’re supposed to swap it back when you return to lower elevations, a task most people ignore.

Your fuel choice has huge implications for self-reliance. Tapping into your vehicle’s main diesel or gasoline tank is the ultimate in convenience, simplifying your logistics to a single fuel source. Propane is universally available, but it means carrying, monitoring, and refilling separate tanks, which can be a hassle on long trips in remote areas.

Installation and Safety at High Elevation

No matter which furnace you choose, proper installation is paramount. A poorly installed heater is a fire hazard and a carbon monoxide threat anywhere, but the risks are amplified at high elevations where incomplete combustion is more likely. Follow the manufacturer’s instructions to the letter, especially regarding clearances, exhaust routing, and fuel line connections. If you’re not 100% confident, hire a professional.

A working carbon monoxide (CO) detector is not optional; it is essential. In fact, you should have two. The thin air at altitude can already cause symptoms like headaches and dizziness, which can easily be confused with the early stages of CO poisoning. Your detector is the only reliable way to know if there’s a problem.

Finally, remember that all combustion creates moisture. Even with a sealed, direct-vent heater, the water vapor from your breath and cooking will condense on cold surfaces. Ensure you have a plan for ventilation, even if it’s just cracking a roof vent, to manage humidity and maintain good air quality inside your mountain sanctuary.

Ultimately, the best high-altitude furnace is the one that safely and reliably keeps you warm, extending your travel season and opening up new territories. It’s an investment not just in comfort, but in the capability and freedom that self-reliant RVing is all about. By matching the right technology to your fuel type and travel style, you can ensure your mountain home on wheels is always a warm and welcoming refuge.