Feature in the Spotlight: The Truma Combi Water Heater Furnace

While technology and the sciences continue to advance at a rapid pace, the same can’t be said for the technological advancements in the American RV industry. Indeed, with the exception of the slide-out and the Toy Hauler, advancements in the RV industry have been pretty much nil lately. If any breakthroughs have occurred, it’s been due to either European innovations—like the DC compressor refrigerator, Seitz window, and folding bathroom sink—or innovations outside the RV marketplace like the LED light, the lithium ion battery, and solar power. Fortunately, our friends in Europe have kept the technology train moving by developing revolutionary products for the RV industry. The latest, and most significant advancement comes from Germany, the so-called Truma Combi. What’s great about this amazing little unit is that it functions as both a water heater and a furnace and does so with a 97 percent efficiency.

The benefits of the Truma Combi are numerous. First, the dual capable unit takes up half the space in your RV since only one appliance is needed rather than two. Small rigs, like truck campers, can really benefit from the smaller footprint by utilizing the extra space for things like storage or an extra battery. The other savings, of course, is in weight. The smallest offering by Truma—the Combi 4—weighs only 31 pounds. The combined weight of your typical American 30,000 BTU furnace and American 6 gallon water heater is 54 pounds (30 pounds of the furnace and 24 pounds for the water heater with an empty tank). That’s a pretty significant savings in weight, especially for truck campers when every pound matters. Moreover, the versatile Truma Combi can run on propane (a diesel version is also available), 12 volt power, or both. The amp draw of the unit is quite low, too, with an average power consumption of only 1.1 amps for air heating and 0.4 amps during the water up heat cycle.

The Truma Combi offers additional benefits to the owner. The Combi 4 utilizes a two-burner flame, making it more efficient by providing two temperature settings (the larger, more capable Combi 6 provides a three burner flame for three temperature settings). Moreover, the unit is nearly silent when it operates. Gone are days of being awakened in the middle of the night by the roar of your furnace. In addition, the heating elements of the Truma Combi are mounted outside the water tank not inside like the traditional water heater. If you’ve ever had to replace a corroded anode rod in a traditional water heater, you’ll really appreciate this feature. Not only that, but draining the 2.6 gallon water tank for winterizing is easier, too—all you have to do is flip a switch. Finally, the Combi has a programmable thermostat that makes operating the unit a breeze.

The Truma Combi is now being sold here in the USA with an office recently opening in Elkhart, Indiana. RV manufacturing giant, Winnebago, has recently gotten onboard and is now offering the versatile, little unit in their Travato traveling van. Likewise Airstream is now installing them in their portable Basecamp models. Unfortunately, due to the $1,500 price tag, truck camper manufacturers have been slow to move. To my knowledge, only one truck camper company—BundutecUSA—currently offers the Truma Combi as an option. Yes, the Truma Combi is expensive, but when you consider the amount of space and weight that it saves and how efficiently it operates, it makes a lot of sense to have one in your rig, especially if you do a lot of boondocking and overlanding. It’s time for truck camper manufacturers to get on board on what really is a no-brainer product and stop using antiquated 1960’s technology. As a matter of fact, the benefits of the Truma Combi are so significant, we’re seriously considering having one retrofitted in my truck camper.

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About Mello Mike 523 Articles
Mello Mike is an Arizona native, author, and the founder of Truck Camper Adventure. He's been RV'ing since 2002, is a certified RVIA Level 1 RV Technician, and has restored several Airstream travel trailers. He currently rolls in a 2013 Ram 3500 with a 2021 Bundutec Roadrunner truck camper mounted on top. He retired from the U.S. Navy in 2004 as a CWO3 after 24 years, worked in project management, and now runs Truck Camper Adventure full-time. He also does some RV consulting, repairs, and inspections on the side.


  1. Mike,
    There is a fair amount of info and reviews of the Truma Combi propane, but almost nothing on the diesel D6E. Is there any way you could get hold of a D6E for a thorough evaluation? You could have the ONLY rock-solid review on the web.

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