Switching to an atwood tankless water heater was probably the best upgrade I ever made to my rig. If you've spent any amount of time living in an RV or a travel trailer, you know the "six-gallon struggle" all too well. You get about four minutes of lukewarm bliss before the water turns icy, leaving you soapy and shivering while you wait for the recovery time. Moving to a tankless system changes that dynamic entirely, but it also comes with a few quirks that nobody really tells you about until you're already standing in the shower.
Why the Move to Tankless Makes Sense
The biggest draw, obviously, is the endless hot water. With an atwood tankless water heater, you aren't limited by the size of a metal cylinder sitting in your side panel. Instead, the unit uses a high-output burner to heat the water as it flows through a heat exchanger. As long as you have propane and a steady water source, you can stay in that shower until your skin wrinkles. For families or anyone traveling with a partner, this is a massive quality-of-life improvement. No more scheduling shower times or arguing over who used up all the "good water."
Another thing people overlook is the weight. A standard six or ten-gallon water heater holds, well, six or ten gallons of water. Since water weighs about eight pounds per gallon, you're lugging around an extra 50 to 80 pounds just in your heater. By going tankless, you're shedding that weight. It might not seem like much in the grand scheme of a heavy RV, but every little bit helps when it comes to fuel economy and staying under your GVWR.
Understanding the "Atwood Way"
It's worth noting that Atwood (now part of the Dometic family) designed their tankless units to be a direct fit for most standard RV water heater cutouts. This is a huge win for DIYers. If you're pulling out an old Atwood 6-gallon unit, the tankless version usually slides right into that same square hole. You don't have to go hacking into the side of your fiberglass or aluminum skin, which is always a nerve-wracking experience.
The way these units work is pretty clever. They use a modulating burner, which basically means the computer inside the heater looks at how cold the incoming water is and how fast it's flowing, then adjusts the flame height to hit the target temperature. It's not just "on or off"; it's a smart system that tries to stay efficient. However, because it's a high-tech piece of gear, it expects things to be just right—especially your water pressure.
The Learning Curve: It's Not Like Your House
If you're coming from a sticks-and-bricks house where you have a massive residential tankless unit, you might be surprised by how different the RV version feels. The most common complaint people have when they first start using an atwood tankless water heater is what we call the "cold water sandwich."
This happens when you turn the water off to soap up and then turn it back on to rinse. For a few seconds, you get the hot water that was left in the pipe, followed by a brief burst of cold water (the water that flowed through the heater while the burner was just starting up), and then it gets hot again. It takes a little practice to get the timing right, or you might find yourself just letting the water run the whole time—which is fine if you're on a full hookup site, but not so great for boondocking.
Don't Mix Your Water
Here is the golden rule for these heaters: don't use the cold water knob. In a regular shower, you turn on the hot and then add cold until it's comfortable. If you do that with a tankless unit, you might actually lower the flow rate of the hot water so much that the burner shuts off.
The best way to use an atwood tankless water heater is to set the thermostat on the wall to exactly the temperature you want for your shower (maybe 105 or 110 degrees) and then turn the hot water knob all the way on. Let the heater do the work of regulating the temp. It feels weird at first, but it makes the experience much more consistent.
Installation and Retrofitting
If you're thinking about swapping your old tank unit for an atwood tankless water heater, the process is fairly straightforward but requires some basic plumbing and gas skills. Since the unit is designed to fit the standard 12.5" x 12.5" or 16" x 16" openings, the physical mounting is usually the easiest part.
You'll need to reconnect your PEX lines—hot and cold—and your propane line. The most important part of the install, though, is the door kit. You have to make sure you get the right cover plate to hide the gaps if your old unit was larger. Also, keep in mind that these units need a 12V power source for the control board and the igniter. If your old heater was a pilot light model with no electrical hookup, you'll need to fish some wires to the spot.
Maintenance and Keeping the Unit Happy
One thing I've learned the hard way is that these units hate hard water. Because the tubes inside the heat exchanger are much smaller than a big 6-gallon tank, calcium and scale can build up quickly. If you notice your water isn't getting as hot as it used to, or if the flow seems restricted, it's probably time for a descale.
Every year or so (depending on how much you travel), you should run a white vinegar solution through the heater. Most people set up a simple bypass loop with a small pump and a bucket. Let it circulate for about an hour, and it'll eat away all that gunk. It's a bit of a chore, but it's much cheaper than replacing the whole heat exchanger because it got clogged up and cracked.
Dealing with Wind and Airflow
Because the atwood tankless water heater is a high-BTU device, it needs to breathe. Sometimes, if you're camped in a spot with heavy crosswinds hitting the side of your rig, the flame can get blown out or struggle to stay consistent. If you find your heater "short cycling" (turning on and off rapidly), check the exterior vent. Make sure there are no bird nests or wasp hives in there—seriously, wasps love the smell of propane and the warmth of those vents.
Is it the Right Choice for You?
Is an atwood tankless water heater right for everyone? Maybe not. If you spend 100% of your time boondocking in the middle of the desert with a limited water supply, a tankless unit might actually frustrate you. You tend to waste a little more water waiting for the "hot" to reach the faucet compared to a tank unit that's already sitting there hot.
But for the "weekender" who stays at state parks, or the full-timer who lives in their rig at an RV resort, it's a total game changer. There is something incredibly luxury-feeling about taking a 15-minute shower in an RV without a single worry about the water turning cold. It makes the rig feel less like a "camper" and more like a home.
In the end, it's all about how you use your space. If you value comfort and you're tired of the "navy shower" routine, making the jump to tankless is a move you probably won't regret. Just remember to keep it clean, watch your water pressure, and stop touching that cold water knob! It takes a minute to adjust your habits, but once you do, you'll never want to go back to a standard tank again.