6 Best Direct Vent Furnaces For RV Living That Unlock Year-Round Travel

Waking up to frost on the inside of your RV windows is a stark reminder that three-season camping has its limits. That biting cold is the wall many RVers hit, forcing them to winterize and wait for spring. But the right furnace doesn’t just fight the chill; it unlocks the other half of the calendar, turning your rig into a true four-season home on wheels.

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Why Direct Vent Furnaces Are Essential for RVs

A direct vent furnace is non-negotiable for serious cold-weather RVing. Unlike a portable propane heater that combusts indoor air and releases moisture and carbon monoxide inside your living space, a direct vent system is a sealed loop. It draws fresh air for combustion from the outside through one pipe and exhausts all the dangerous fumes, like carbon monoxide, back outside through another.

This sealed system is the gold standard for two critical reasons: safety and moisture control. You can sleep soundly knowing the combustion process is completely isolated from your living area. There’s no risk of oxygen depletion or carbon monoxide buildup, which are life-threatening concerns with unvented heaters.

Furthermore, burning propane creates a surprising amount of water vapor. An unvented heater dumps that moisture directly into your rig, leading to relentless condensation, mold, and mildew. A direct vent furnace expels that moisture outside, keeping your small space dry and healthy. It’s the difference between a damp, chilly box and a warm, comfortable home.

Suburban SF-35FQ: The Reliable RV Workhorse

If you’ve been in more than a few factory-built RVs, you’ve likely seen a Suburban furnace. They are the industry standard for a reason: they are simple, powerful, and incredibly reliable. The SF-35FQ, with its 35,000 BTU output, is a common sight in mid-to-large-sized trailers and motorhomes, capable of keeping a 35-foot fifth wheel toasty in freezing temperatures.

The biggest advantage of a Suburban is its ubiquity. You can find parts for it in almost any RV service center across North America, and nearly any mobile tech knows how to work on one. This is a massive benefit when you’re in a remote town in Montana and your furnace decides to act up on a 10-degree night. There’s no waiting for specialty parts to be shipped from Germany.

The trade-offs? They aren’t the quietest units, and their single-speed fan can be a bit of a power hog on your 12-volt system. When it kicks on, you know it. But for many, that’s a small price to pay for proven, coast-to-coast reliability and serviceability. It’s the trusty pickup truck of the RV furnace world.

Dometic DF Series: Quiet, Efficient Heating

Dometic is Suburban’s main competitor, and their DF series furnaces offer a slightly more refined heating experience. They are engineered to be quieter, with a focus on smoother fan operation that reduces the "jet engine" roar that can sometimes accompany older furnace models. This makes a real difference in a small space, especially for light sleepers.

Functionally, the Dometic units are very similar to Suburbans. They are robust, ducted systems designed to heat an entire coach efficiently. Many RVers who replace an old furnace often choose Dometic as an upgrade, specifically seeking that lower noise level and modern efficiency. They install into similar footprints, making a swap relatively straightforward.

Like Suburban, Dometic enjoys a wide service network, ensuring you can find help when needed. The choice between the two often comes down to brand preference or a specific model’s fit for your RV’s existing cutouts and ductwork. Think of it as choosing between two excellent, competing tool brands—both get the job done well, but one might feel slightly better in your hand.

Propex HS2000: Compact Propane Heat for Vans

For van conversions, skoolies, and smaller trailers, a big 30,000 BTU furnace is overkill. That’s where the Propex HS2000 shines. This compact, UK-made furnace is specifically designed for small, often off-grid, spaces. It sips propane and uses very little 12-volt power, making it a favorite among van lifers who count every amp-hour.

The HS2000’s small size allows for creative mounting options, like inside a cabinet or under a bed, preserving precious living space. It’s also exceptionally quiet, producing a gentle hum rather than a roar. This is a game-changer in a 70-square-foot van where the furnace is never more than a few feet away from your head.

Its 6,500 BTU output is perfect for keeping a well-insulated van warm down to freezing temperatures without turning it into a sauna. It provides a consistent, gentle heat that avoids the drastic temperature swings of an oversized furnace. For small-scale living, right-sizing your heater is just as important as its power.

Truma VarioHeat: Premium German Engineering

Truma represents the high-end of the RV furnace market, and the VarioHeat is their flagship product. This is a furnace for those who prioritize quiet operation, fuel efficiency, and smart features. Instead of a single-speed fan, the VarioHeat uses a variable-speed motor that intelligently adjusts its output to maintain a set temperature.

This smart modulation means the furnace runs longer at a lower, quieter speed, providing even, consistent heat while using less propane and battery power. It also features a "night mode" that is whisper-quiet, a major selling point for anyone who’s been woken up by a furnace kicking on. It’s compact, lightweight, and incredibly efficient.

Of course, premium engineering comes with a premium price tag. A Truma unit can cost significantly more than a comparable Suburban or Dometic. But for full-timers or those who spend extended time in cold climates, the investment can pay off in fuel savings, improved comfort, and a better night’s sleep.

Dickinson Newport P9000: A Marine-Grade Option

Stepping away from traditional forced-air furnaces, the Dickinson Newport offers a different approach to heat. This is a small, direct-vent propane fireplace, originally designed for the harsh, damp environment of sailboats. Its stainless-steel construction is built to last, and its operation is beautifully simple.

The Newport provides radiant heat, which feels different—like the warmth from a wood stove. It warms objects in the room, creating a cozy, dry heat that many people prefer. It uses a tiny, built-in 12-volt fan to help circulate air, but it can even run without power during an outage, providing a crucial safety net. The small flame visible through the glass window adds a level of ambiance no forced-air furnace can match.

Installation is more involved than a standard RV furnace, requiring a dedicated chimney through the roof or wall. It’s also not a ducted system, so it’s best for open-plan layouts like vans or small Airstreams. For the right build, it’s a reliable, non-electric, and aesthetically pleasing heating solution.

Atwood AFMD20: A Legacy of Compact Performance

For years, Atwood was a trusted name in RV appliances before being acquired by Dometic. You’ll still find thousands of their furnaces in service, and the AFMD20 model is a testament to their legacy of building compact, reliable heaters. Sized at 20,000 BTUs, it was the go-to furnace for smaller travel trailers, truck campers, and Class B motorhomes.

These units are known for being workhorses. They are simple, easy to diagnose, and parts are still readily available. The design is compact, allowing them to be tucked into small cabinetry without sacrificing much storage. For anyone buying a used RV from the last two decades, there’s a good chance an Atwood is installed.

While new units are now branded as Dometic, the underlying design principles of the Atwood legacy models persist. They represent a solid, no-frills heating solution that has been proven over millions of miles. If you have one, it’s worth maintaining; if you’re looking for a replacement in a smaller rig, its modern Dometic equivalent is a direct and worthy successor.

Choosing Your Furnace: Sizing BTUs Correctly

Picking the right brand is only half the battle; you have to get the size right. Furnace output is measured in BTUs (British Thermal Units), which is simply a measure of heat energy. A common mistake is thinking "bigger is always better," but an oversized furnace is just as problematic as an undersized one.

An undersized furnace will run constantly and still fail to keep you warm, straining your battery and propane supply. An oversized furnace will "short cycle"—it will blast hot air, quickly satisfy the thermostat, and shut off, only to repeat the process a few minutes later. This is inefficient, creates uncomfortable temperature swings, and fails to circulate air long enough to manage humidity.

A good rule of thumb is to budget around 1,000 BTUs per foot of RV length, but you must adjust for your specific situation.

• Poor Insulation: If you have an older rig or single-pane windows, size up.
• Extreme Cold: If you plan to camp in sub-zero temps, you’ll need more power.
• Four-Season Package: A well-insulated rig with double-pane windows can get by with a smaller, more efficient unit.

Measure your space, be honest about your insulation, and consider your travel plans. This will guide you to a furnace that keeps you comfortable without wasting fuel or power.

Your furnace is more than an appliance; it’s the key that unlocks year-round freedom and transforms your RV into a true, all-weather home. By understanding the tradeoffs between reliability, noise, efficiency, and size, you can choose a system that perfectly matches your rig and your adventure. The right choice will have you planning your next winter trip, not dreading it.