What an RV combo unit does and why it matters

An RV air conditioner and heater combo is a single mounted unit that cools your RV in summer and heats it in winter, usually installed on the roof. Instead of buying and installing two separate systems, a combo handles both jobs from one box. This saves weight, roof space, and installation cost — all things that matter in an RV where every pound and inch counts.

The trade-off is that combo units are typically smaller and less powerful than dedicated air conditioners or furnaces. They work best in mild to moderate climates and for RVs that don't need extreme cooling or heating. If you live in your RV year-round in very cold or very hot regions, a dedicated heating system plus a full-size AC unit may serve you better, but for seasonal travel or moderate climates, a combo handles both seasons without the bulk.

Key Takeaways

  • Combo units mount on the roof and pull power from your RV's electrical system, so you need to know your available amperage before you buy.
  • Cooling capacity is measured in BTU (British Thermal Units), and most RV combos range from 11,000 to 15,000 BTU — enough for small to mid-size RVs in mild climates.
  • Heating output varies widely between models; some combos heat with a small electric element, while others use a heat pump that works down to freezing or below.
  • Installation requires roof penetration and ductwork, so budget for professional installation unless you have RV electrical and carpentry experience.
  • Common brands include Dometic, Coleman, and Atwood, each with different power requirements and heating capabilities.

How to measure your RV's power supply before buying

Every combo unit draws power from your RV's electrical panel, and the amount it draws matters. Most units need either 30-amp or 50-amp service. If your RV has 30-amp service and you buy a unit that needs 50-amp, it will trip your breaker when you run it. If you have 50-amp service, a 30-amp unit will work fine but won't cool or heat as effectively.

Check your RV's main electrical panel — it's usually a metal box inside a cabinet or under a seat. Look at the breaker labeled "AC" or "Air Conditioner." The number on that breaker (30 or 50) tells you your service level. Write this down. You'll also want to know whether your RV has a generator and what size it is, because running a combo unit on generator power is possible but uses fuel quickly.

If you're not sure, ask your RV dealer or look at your RV's spec sheet. This one number — your amp service — narrows down which units will actually work in your RV.

Understanding BTU and cooling capacity

BTU stands for British Thermal Unit, and it measures how much heat a unit can move. For cooling, a higher BTU number means the unit can cool a larger space or cool faster. Most RV combo units range from 11,000 to 15,000 BTU. A rough rule is that you need about 300 to 400 BTU per 100 square feet of RV interior.

A small Class B van or travel trailer might need 11,000 to 13,000 BTU. A mid-size Class C motorhome or larger travel trailer might need 13,000 to 15,000 BTU. If your RV is very large or you live in a hot climate, you may need two combo units or a dedicated full-size air conditioner instead.

The cooling capacity listed on the box is what the unit can do under ideal conditions. In real use — when it's very hot outside, your RV is in direct sun, and you have people and appliances running inside — the actual cooling will be somewhat less. This is normal and expected.

Heating options: electric elements versus heat pumps

This is where combo units differ most from each other. Some use a straightforward electric heating element, like a space heater. These are cheap and work fine down to about 50°F outside, but they draw a lot of power and don't work well in cold weather. Others use a heat pump, which is more efficient and can heat even when it's freezing outside.

A heat pump combo moves heat from outside air into your RV, even in cold weather. It uses less power than an electric element and works down to 0°F or lower depending on the model. The downside is that heat pump combos cost more upfront. If you only RV in warm months or mild climates, an electric-element combo is fine. If you travel in winter or live in a cold region, a heat pump is worth the extra cost.

Check the spec sheet for the heating output in BTU and the lowest outdoor temperature at which the unit will heat. This tells you whether it will actually work in the climate where you'll use it.

Common RV combo unit brands and their differences

Dometic makes the Penguin and Brisk Air lines. Penguin units are popular in Class B vans and small travel trailers; they're compact and come in both electric and heat pump versions. Brisk Air is larger and more powerful, suited to bigger RVs. Dometic units tend to be on the higher end of the price range but are known for reliability.

Coleman makes the Mach series, which is widely available and reasonably priced. Mach units are straightforward — most use electric heating — and they work well for seasonal RVers who don't need extreme cold performance. They're common in rental RVs and entry-level motorhomes.

Atwood makes compact units often found in travel trailers and smaller motorhomes. Atwood combos are typically lighter and cheaper than Dometic or Coleman, which appeals to RV owners watching weight. They're less common in the aftermarket, so parts and service can be harder to find in some areas.

Other brands like Furrion and Truma exist but are less common in North America. Before you buy, check what's available for service and parts in the regions where you travel. A cheap unit is not a bargain if you can't get it fixed on the road.

Installation: roof penetration and ductwork

Installing a combo unit is not a weekend DIY job unless you have experience with RV electrical systems and roof work. The unit mounts on the roof, which means cutting a hole through the roof and sealing it properly to prevent leaks. The ducting runs inside the RV to distribute cool or warm air. The electrical connection ties into your RV's main panel.

A professional RV technician or shop will handle this work. Expect to pay $500 to $1,500 for installation labor, depending on your RV's layout and whether any existing ductwork can be reused. If you're replacing an old combo unit with a new one of the same size, installation is simpler and cheaper. If you're adding a combo to an RV that never had one, or upgrading to a larger unit, the work is more involved.

Get quotes from at least two RV service shops before you commit. Ask whether they warranty their work and what happens if the roof leaks after installation. A good shop will stand behind their sealing work.

Power draw and generator considerations

A combo unit running on AC power (plugged into shore power or running a generator) draws significant amperage. A 15,000 BTU unit might draw 12 to 15 amps when cooling. If you're running other appliances at the same time — a microwave, water heater, or other AC devices — you can easily exceed your available power and trip a breaker.

Running a combo on a generator is possible but expensive in fuel. A typical RV generator produces 5,000 to 7,500 watts. A combo unit running at full cooling might use 1,500 to 2,000 watts, leaving little room for anything else. Many RV owners run their combo during the day when plugged into shore power and rely on fans or the unit's heating mode (which uses less power) when on generator alone.

If you plan to boondock — camp without shore power — and rely on your generator for cooling, you'll want a smaller, more efficient combo unit and realistic expectations about how long your fuel will last.

Frequently Asked Questions

Can I install a combo unit myself if I'm handy?

You can if you have experience with RV electrical systems, roof work, and sealing. The biggest risk is a roof leak, which can cause serious water damage. If you're not confident in your sealing work, hire a professional for at least the roof penetration and sealing. Many RV owners do the ductwork themselves after a professional installs the unit.

What's the difference between a combo unit and two separate systems?

A combo saves weight and roof space but sacrifices some power. A dedicated air conditioner and furnace can be larger and more powerful, but they take up more room and cost more to install. For full-time RVers in extreme climates, separate systems are often better. For seasonal travelers, a combo is usually enough.

How long does a combo unit last?

Most RV combo units last 10 to 15 years with normal use. Lifespan depends on how often you run it, how well you maintain it, and the climate where you use it. Running a unit constantly in very hot weather wears it out faster than seasonal use in mild climates.

Do I need to winterize my combo unit?

If you store your RV in winter and won't use the heating, you don't need to do anything special. If you use the unit in cold weather, make sure the outdoor coils stay clear of ice and snow. Some owners cover the outdoor unit in winter, but check your manual first — some units need airflow even when not running.

Can I add a second combo unit if one isn't enough?

Yes, but it requires a second roof penetration, separate ductwork, and additional electrical capacity. Two smaller units can sometimes work better than one large one if your RV has separate sleeping and living areas. Get a professional assessment of your roof and electrical system before committing to a second unit.