Best RV Propane Furnace Upgrades for Cold Weather

By Jake Morris — RV Gear Expert & Contributing Editor· June 11, 2026· 11 min read

Written by Jake Morris Senior RV Gear Writer at ShopRVGear

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Jake has spent 8 years full-timing in a Class A motorhome and has personally tested hundreds of RV products across North America. He is the lead gear reviewer at Shop RV Gear, covering solar setups, backup safety syst…

8 yrs experience·Last updated: Jun 11, 2026

Short answer: the best RV propane furnace upgrades for real cold weather

If you winter camp, the single best upgrade for most rigs is swapping to a high‑output Dometic or Suburban propane furnace matched to your existing cutout and BTU needs, then pairing it with targeted add‑on heat (like a Camco Olympian catalytic heater) and smart ducting/insulation upgrades.[1][8][9] This combo keeps the coach, underbelly, and tanks warm without burning through an insane amount of propane. For small and mid‑size rigs, a compact high‑efficiency 30,000 BTU furnace plus better ducting is usually enough.[1][5] Larger fifth wheels and Class A’s often need a 35,000–40,000 BTU furnace or dual‑furnace setup.[1][4]

Below I’ll walk through the best replacement propane furnaces, add‑on heaters that actually help, and critical installation and safety tips—based on what works in real freezing conditions, not just what looks good on a spec sheet.

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How to choose the right RV furnace upgrade (before you buy anything)

Before we talk specific models, get your sizing and goals straight. Most people either:

1. Freeze in a marginal factory furnace that short‑cycles and leaves cold spots, or
2. Oversize the furnace, roast in the living area, and still have cold tanks and a frozen bedroom.

Focus on these five factors:

• BTU size vs. rig size and insulation
  As a rough starting point, many RV pros suggest:

  
  • Up to ~24 ft: 20,000–25,000 BTU
  • 24–30 ft: 25,000–30,000 BTU
  • 30–36 ft or large slide‑heavy rigs: 30,000–40,000 BTU[4][5]
    Bump up if your rig is poorly insulated, has lots of glass, or you camp below freezing regularly.

• Cutout and footprint
  Your replacement furnace must match or closely fit your existing cutout, gas line, and duct routing.[1][8] Suburban and Dometic designs often have direct‑replacement models for each other, but always check dimensions, vent location, and 12V wiring.

• Ducting and underbelly heating
  Cold‑weather comfort depends as much on where the hot air goes as on furnace BTUs. Many good upgrades are just better ducting to the bedroom, bath, and underbelly so tanks and lines don’t freeze.[1][3]

• Efficiency and propane use
  Newer high‑efficiency RV furnaces can burn less propane for the same heat and run quieter.[5][6] That matters if you boondock and refill less often.

• Electric vs. propane strategy
  For true cold‑weather reliability, you still want a propane furnace as your primary heat (it warms the underbelly and doesn’t depend on 120V hookups). Electric space heaters are fine supplements, not replacements.[2]

Best overall RV propane furnace upgrade (most rigs)

1. Dometic Mojave Large LP Furnace – best overall performance for cold weather

Why it’s my top pick:
The Dometic Mojave Large LP furnace line is consistently recommended as a high‑output, reliable upgrade for mid‑size to larger RVs that see real cold weather.[1][5] It delivers strong BTU output, good parts support, and straightforward replacements for many older Dometic/Atwood units.

Key highlights

• Designed as a direct or near‑direct replacement for many OEM furnaces[1]
• Available in multiple BTU options (commonly around 30,000–40,000 BTU depending on model)[1][5]
• Forced‑air propane heat that can be ducted to multiple zones (living, bath, bedroom, underbelly)[1]
• Proven performance in cold‑weather RV heating system roundups[1]

Best for:

• Travel trailers and fifth wheels in the 28–36 ft range
• Class C or small Class A rigs with a single furnace and poor cold‑weather performance
• RVers who want a like‑for‑like swap with more output and reliability, not a custom build

Pros

• Strong, even heat output for most full‑size rigs[1]
• Widely supported with replacement parts and service knowledge[1][8]
• Multiple BTU options so you can size correctly
• Compatible with standard RV thermostats

Cons

• Requires careful matching of model, BTU rating, and dimensions to your existing unit
• Still a traditional RV furnace – not a condensing or ultra‑high‑tech home unit
• Blower fan noise is noticeable, though comparable to Suburban

Who should skip it:
If you have a very small rig (under ~22 ft) or a single‑duct older camper, the Mojave Large line may be overkill; look at compact 20–25k BTU units instead.[5]

Best high‑output upgrade for large rigs and fifth wheels

2. Suburban SFV‑Q Series – best for high‑output, ducted systems

The Suburban SFV‑Q Series is frequently cited as a high‑output choice for larger RVs and multi‑duct layouts.[1][4][5] Suburban furnaces are common in factory builds, so upgrading within the Suburban family often simplifies the install.

Why it stands out

• Designed for high BTU output suitable for larger fifth wheels and Class A’s[1]
• Quiet‑series improvements in the SFV‑Q line help reduce blower noise compared to older models[1]
• Works well with multi‑duct installations to heat multiple zones and enclosed underbellies[1][4]

Best for:

• Fifth wheels and Class A’s 30–40 ft + with big interior volume
• Rigs that already have a Suburban furnace and want a drop‑in upgrade
• Winter campers who regularly sit below freezing and need strong airflow to tanks and bays

Pros

• Serious BTU output for big spaces[1][5]
• Strong brand reputation and widespread parts availability[1][8]
• Good match for dual‑furnace setups (front/back)

Cons

• Overkill for small trailers and camper vans
• Higher propane consumption at max output (normal for this BTU class)
• As with all Suburban units, you need to stay on top of maintenance and return‑air path clearance to avoid overheating issues[3]

Who should skip it:
If you mostly chase mild weather and only occasionally see frost, a smaller Mojave or compact furnace is a better fit; you don’t need this much furnace.

Best compact furnace upgrade for smaller RVs

3. Dometic LP Gas Furnace DFMD30111 – best compact option

For smaller travel trailers, truck campers, and compact Class C rigs, the Dometic LP Gas Furnace DFMD30111 is frequently highlighted as a compact, efficient upgrade.[1][5]

Why it’s a strong pick

• Compact form factor that fits tight spaces and small cabinets[1]
• Around 30,000 BTU class (verify exact BTU for the specific DFMD model you’re considering)[1][5]
• Works well in single‑ or dual‑duct installations on shorter rigs

Best for:

• Travel trailers and hybrid trailers under ~26 ft
• Truck campers needing a modern, efficient furnace in a small cutout
• Van conversions that want a traditional RV furnace rather than a diesel or hydronic system

Pros

• Small footprint but serious heat for smaller spaces[1]
• Good match for rigs that can’t swallow a full‑size Mojave or Suburban furnace
• Parts and service relatively easy to find

Cons

• Not ideal for large fifth wheels or Class A rigs
• As a compact unit, ducting options can be more limited than full‑size furnaces

Who should skip it:
If your rig is over ~28 ft with slides and a big open living room, step up to the Mojave Large or a Suburban SFV‑Q instead.

Best off‑grid supplemental heater to pair with your furnace

4. Camco Olympian Wave‑6 Catalytic Heater – best off‑grid supplement

The Camco Olympian Wave‑6 catalytic heater is repeatedly recommended as the best off‑grid supplemental propane heater for RVs.[1][9] It doesn’t replace your furnace (it does not heat the underbelly), but it reduces furnace runtime, saves propane, and provides cozy radiant heat.

Why it belongs in a cold‑weather setup

• Catalytic heater with no fan, so it’s silent and uses no 12V power[1]
• 6000 BTU class output (check exact specs for your model) – solid for small to mid‑size living areas[1]
• Mounts on a wall or used on the floor with a stand (follow manufacturer guidance for clearances and ventilation)

Best for:

• Boondockers who want to save battery and propane by reducing furnace usage[1]
• Anyone who hates the furnace cycling noise all night

Pros

• Very efficient propane usage vs. a forced‑air furnace for the same comfort level[1]
• No moving parts = low maintenance
• Heat feels more even and gentle than blast‑furnace air

Cons

• Does not heat tanks or underbelly – you must still use your main furnace in real cold[1]
• Requires proper ventilation and a working propane detector (as with any unvented heater)
• Radiant heat – works best in the room it’s in, not as whole‑rig heat

Who should skip it:
If you only stay at full‑hookup parks and can run electric space heaters, a catalytic heater is less critical.

Other smart propane furnace upgrade paths

Not everyone needs (or wants) to swap out the whole furnace. These upgrade paths often deliver more comfort for less money.

5. Upgrade to a high‑efficiency RV furnace

Some newer RV furnaces are designed as higher‑efficiency drop‑ins that reduce propane usage and can run quieter than older designs.[5][6] According to RV owners who have upgraded, they notice less frequent cycling, better temperature control, and lower fuel use.[6]

What to look for

• Same or slightly higher BTU rating as your existing furnace
• Sealed combustion and modern ignition control
• Manufacturer claims of higher efficiency vs. older models[5][6]

When this makes sense

• Your existing furnace is 10–15+ years old
• You boondock and value propane efficiency
• You want to reduce noise and cycling without upsizing BTUs

6. Add or reroute furnace ducts to critical areas

Many “cold” rigs really just have bad ducting. You can often:

• Add a small branch duct to the bathroom or bedroom
• Add a flex‑duct run into the enclosed underbelly or tank area (if your furnace allows)
• Replace crushed or kinked ducts and poorly cut vents[1][3]

This is one of the cheapest upgrades that makes the biggest difference in cold weather comfort.

7. Install tank and pipe protection

Your furnace upgrade only goes so far if your tanks, lines, and valves are still sitting in the cold.

Common add‑ons:

• Heated tank pads (12V or 120V) stuck to the undersides of fresh, gray, and black tanks
• Pipe heat tape (carefully installed, following manufacturer directions)
• Foam insulation around exposed PEX runs

Even with those, the propane furnace is still your primary freeze protection. Electric pads are backup, not a replacement.

Safety and installation tips for any propane furnace upgrade

Work with propane like it can bite you (because it can)

According to propane safety guidance, any propane work should be leak‑checked with soapy water at all connections; bubbles indicate a leak.[2] After any furnace swap or gas line modification:

• Use soapy water on every new connection and watch for bubbles[2]
• Check with a manometer (or have an RV tech do it) to confirm proper gas pressure
• Verify your propane detector and CO detector are working and not past their expiry dates

Venting and combustion air

Improper venting is how you get condensation, soot, and CO issues.

• Ensure the exhaust/intake assembly matches the furnace model
• Check that the exterior vent is clean and not blocked by nests, debris, or snow
• Maintain clearances around the furnace cabinet for return air and service access[3]

Electrical and thermostat wiring

Most RV propane furnaces use 12V DC control circuits and blowers.[3][5]

• Confirm the wire gauge and fusing match the furnace requirements
• If upgrading to a new thermostat, follow a wiring diagram from the furnace or thermostat manufacturer
• Poor 12V wiring equals weak blower, lockouts, and poor combustion

When to call an RV tech

Do not DIY the install if:

• You are unfamiliar with propane plumbing and leak testing
• You’re changing BTU size significantly and unsure about gas line sizing
• Your existing furnace compartment is tight, modified, or water‑damaged

A good RV tech can also help you tune ducting so you’re not roasting the living room while the bath stays cold.

Cheap furnace upgrades that make a big difference

You don’t have to spend four figures to stay warm. Consider these quick wins first:

1. Seal drafts: Use foam, weatherstripping, and outlet gaskets around slide rooms, basement doors, and cabover seams.
2. Reflective window inserts: Reflectix‑style cutouts for large windows reduce heat loss dramatically at night.
3. Vent cushions: Foam vent plugs keep heat from pouring out of roof vents.
4. Return air path: Make sure doors aren’t choking airflow; some people add door grilles or under‑cut doors.
5. Proper thermostat placement: If your thermostat is on a cold exterior wall, it will short‑cycle the furnace; relocating it can help.

These mods compound the benefit of any furnace upgrade.

What to skip (or be skeptical about)

From years of cold‑weather camping and watching others waste money, here’s what usually doesn’t pay off for most RVers:

• Trying to heat only with electric space heaters: Works on hookups in mild cold, but leaves tanks and bays unprotected in real winter. Use them as supplements, not primary.[2]
• Huge BTU furnace upgrades without duct changes: You’ll get shorter cycles, more noise, and uneven heat.
• Unvented propane heaters as the only heat source: They can be safe when properly vented and monitored, but they do not warm the underbelly or tanks. Always keep your main furnace functional.[1]
• Random “RV winterization” gadgets with no BTU or wattage specs: If the numbers aren’t clear, assume the effect is minimal.

Frequently Asked Questions

How many BTUs do I need for an RV propane furnace in cold weather?

Most mid‑size RVs are adequately heated by a 25,000–30,000 BTU furnace, while larger fifth wheels and Class A motorhomes often benefit from 30,000–40,000 BTU units.[4][5] Poor insulation, lots of windows, and frequent sub‑freezing camping push you toward the upper end of that range. The goal is steady, comfortable runtime, not short, blast‑furnace cycles.

Is it worth upgrading my RV furnace or should I add space heaters instead?

If you camp in below‑freezing temps, upgrading your propane furnace (or at least your ducting and underbelly heat) is usually worth it because it protects tanks, lines, and bays, which electric space heaters do not.[1][2] Space heaters and catalytic heaters are excellent supplements that can reduce furnace runtime, but they should not replace the furnace as your primary freeze protection.

Can I install an RV propane furnace upgrade myself?

Many experienced DIYers do their own furnace swaps, but you must be comfortable with propane connections, leak testing, and 12V wiring.[2][3][5] If you are changing BTU size, rerouting gas lines, or modifying the vent, it is wise to have an RV technician handle or at least inspect the work.

What’s the safest way to check for propane leaks after an upgrade?

Use a soapy water solution (dish soap and water) in a spray bottle on all newly disturbed gas fittings and look for bubbles, which indicate leaks.[2] Then confirm with a pressure or manometer test if possible, and always verify your propane and CO detectors are powered, in date, and functioning.

Will a catalytic heater replace my RV furnace in winter?

No. A catalytic heater like the Camco Olympian Wave‑6 is a great supplemental heater—quiet, efficient, and comfortable—but it does not heat the underbelly or tanks.[1] In real winter conditions you still need your ducted propane furnace running periodically to prevent frozen tanks and water lines.

All Picks & Comparison

#		Product	Price	Rating
#1		Suburban RP-30FQ 30,000 BTU/h RV Replacement Core for Suburban Furnace Series SF-25F, SF-25FQ, SF-30F, SF-30FQ, SF-FQ (2608A)	$530.00	★★★★☆ (137)	View on Amazon
#2		Suburban RP-30Q 30,000 BTU/h RV Replacement Core for Suburban Furnace Series SF-25, SF-25Q, SF-30, SF-30Q, SF-Q (2607A)	$498.59	★★★★☆ (59)	View on Amazon
#3		Romeda Aluminum Foil Tape, 2 inch x 65 Feet Foil Tape (3.9 mil), Silver Insulation Adhesive Metal Tape, High Temperature Heavy Duty HVAC Tapes for Ductwork, Dryer Vent, HVAC	$6.99	★★★★★ (6,594)	View on Amazon
#4		Frost King CF55 Foil Backed "No Itch" Natural Cotton Duct Wrap, 12-Inch x 1-Inch x 15-Feet	$21.21	★★★★★ (2,123)	View on Amazon
#5		TONDA RV Furnace Vent Screen, Bug Screens Heater Vent Cover for Camper with Installation Tool and Silicone Rubber, 2.8 x 1.3 Inch, 2 Pack	$7.99	★★★★★ (1,513)	View on Amazon