We were parked outside Moab in July 2023 when our 10-gallon tank water heater finally broke us. Three of us needed showers after a day hiking in the dust, and the negotiation started before anyone even turned on the faucet. Who goes first. Who gets the longest shower. Who has to wait 45 minutes for the tank to reheat. We had been doing this dance since 2018, and that night, standing there covered in red dirt, we finally admitted the obvious: this system was not working. We needed a better solution, and after months of research, we decided to upgrade to a tankless water heater for motorhome living.
Two months later we installed a tankless water heater for motorhome use, and the difference was immediate. No more shower negotiations. No more running out of hot water halfway through washing dishes. No more waiting around for a tank to reheat while we stood there in towels.
But the benefits went way beyond endless hot water. Over the next year, we discovered seven specific reasons why switching to a tankless water heater for motorhome living was one of the best upgrades we have ever made to our rig. Some of them we expected. A few of them caught us completely off guard.
The Daily Stuff That Actually Matters: Space, Weight, and Never Running Out of Hot Water Again
The endless hot water thing is real, and it changed our entire routine.
We used to plan our days around who showered when. If we both needed showers after a long drive, one of us was waiting. If we had friends visiting and four people needed to clean up, we were looking at two hours of downtime. Now we shower. All of us. Back to back if we want. The water stays hot as long as the propane holds out, and a 20-pound tank lasts us about four months even with daily cooking and showering.
The space savings were the real surprise, though. Our old Atwood 10-gallon tank took up a massive compartment on the exterior of our fifth wheel. When we pulled it out and installed the Suburban tankless unit, we suddenly had this huge empty bay. We moved our leveling blocks in there, our sewer hose, a folding table, and we still had room left over. That extra storage has been worth as much as the hot water itself.
The weight difference matters too, especially if you are close to your towing limits. A 10-gallon tank full of water weighs about 90 pounds. The tankless unit weighs maybe 20. That is 70 pounds we got back, which we immediately filled with other gear, but still. It counts.
The efficiency gains and lower propane consumption are real, but honestly, we barely notice them. Yes, we are using less fuel because the unit only heats water when we need it instead of keeping a tank hot 24/7. But the propane savings are not dramatic enough to pay back the unit cost anytime soon. The space and the endless hot water are what actually changed our daily life.
What Nobody Warns You About Before You Buy
The upfront cost is no joke. We paid about $600 for the Suburban unit itself, plus another $200 for venting components and fittings we did not have. That is $800 before we even picked up a wrench. If you are paying someone to install it, add another $300 to $500 depending on your rig and how complicated the plumbing is.
The other thing that surprised us: the water temperature fluctuates when you adjust the flow. If you are in the shower and you turn the hot water down even slightly, the whole system shuts off for a minute while it recalibrates. The water goes completely cold. Then it kicks back on and you get scalded. We learned pretty fast to pick a temperature and leave it alone, but that first week was a lot of yelping and cursing.
And if you are used to turning on the tap and getting instant hot water, you are going to be disappointed. Tankless units take about a minute to heat up and deliver hot water to the fixture. At our kitchen sink, which is the farthest point from the heater, we waste more water waiting for it to get hot than we ever did with the tank system. It is manageable, but it is real.
How We Actually Picked Our Tankless Water Heater for Motorhome Use and Installed It Without Destroying Our RV
We went with propane instead of electric because we spend a lot of time boondocking, and running an electric tankless water heater off our batteries and solar would have required a massive electrical upgrade we were not willing to pay for. Electric units pull serious amperage, and unless you are plugged into shore power most of the time, they are not practical. Propane made sense for how we camp.
Sizing the unit was harder than we expected. The National Fire Protection Association has guidelines for BTU capacity based on flow rate, but we tested our actual usage instead. We turned on our shower and our kitchen sink at the same time and measured the combined flow with a bucket and a timer. We were pulling about 2.5 gallons per minute total. That told us we needed a unit rated for at least 3 GPM, which most RV tankless models handle easily.
The venting was the part that almost killed the project. Our old tank heater vented through the floor, but the new tankless unit needed a horizontal vent through the exterior wall. We had to cut a new hole, install a vent cap, and seal everything properly so we did not end up with a leak. That took us an entire afternoon and a lot of sealant. If we had known how much work the venting would be, we might have paid someone to do it.
The water pressure requirement caught us off guard too. Tankless heaters need adequate pressure to activate, and they will not work at all with gravity-fed systems. We tested ours at a campground with notoriously weak water pressure, and the unit kept shutting off mid-shower. We figured out that if we opened a second tap to a tiny trickle, it maintained enough flow to keep the heater running. Not ideal, but it worked.
The whole installation cost us about $850 total, which was more than we budgeted for but less than we feared. And we did it ourselves on a Saturday in September, so we saved the labor cost. If you are planning a similar upgrade to your rig, check out our RV modification guides for more tips on DIY installations that actually work.
You Will Never Run Out Mid-Shower Again
This is the benefit everyone talks about, and it is the one that actually delivers every single day. We have four people in our rig sometimes when friends visit, and everyone showers back to back without a single person getting stuck with cold water. That alone justifies the cost.
The system heats water on demand as it flows through the unit, so as long as you have propane and water pressure, you have hot water. We have run the shower for 20 minutes straight to test it, and the temperature never dropped. Compare that to our old 10-gallon tank, which gave us maybe eight minutes of hot water before it ran out and we were standing there freezing while it reheated.
It Weighs Almost Nothing and Frees Up Serious Storage Space
We already covered this, but it deserves its own section because the storage gain was bigger than we expected. That exterior bay where the old tank lived is now our most-used compartment. We keep all our setup gear in there, and we can access it without digging through three other storage bays first.
The weight savings also helped our towing balance. We were already close to our pin weight limit, and dropping 70 pounds off the rear of the rig made a noticeable difference in how the fifth wheel tracked on the highway.
Propane Lasts Way Longer Than We Expected
We were worried that running a tankless unit would burn through propane, but the opposite turned out to be true. Because the unit only fires up when we are actually using hot water, we are using way less fuel than we did keeping a tank hot all day and night.
In the summer, a single 20-pound propane tank lasts us about four months with daily showers and cooking. In the winter, when we are also running the furnace, that drops to maybe six weeks. But even then, we are using less propane for hot water than we did with the tank system.
It Works Anywhere We Have Propane and Decent Water Pressure
One downside we did not anticipate: most RV tankless water heaters do not have an electric option. That means even when we are plugged into full hookups at a campground, we are still burning propane for hot water. With the old tank system, we could flip a switch and run on electric when it was available. Now we are propane-only, which feels a little wasteful when we are sitting next to a 50-amp pedestal.
But the trade-off is that we can boondock indefinitely as long as we have propane. We do not need shore power to take hot showers, which gives us a lot more freedom when we are camping off-grid.
The Maintenance Routine That Takes 15 Minutes Once a Year
Every spring before we leave Florida for the summer, we spend about 15 minutes flushing the tankless system with white vinegar. We disconnect the water lines, hook up a small pump and a bucket of vinegar solution, and let it circulate through the heat exchanger for 20 minutes. Then we flush it with clean water and reconnect everything.
That is it. That is the entire maintenance routine.
If you skip it, mineral deposits build up inside the heat exchanger and reduce the flow rate. We learned that the hard way our first year when we forgot to flush the system and started getting weak, inconsistent hot water by the end of the season. One vinegar flush fixed it completely.
We also check the burner and the igniter once a year to make sure everything is clean and firing properly. We have been doing it ourselves since we installed the unit and have not had any problems yet.
Before You Buy: The One Question That Determines If This Is Right for Your Rig
Here is the decision framework that matters: How many days a year are you boondocking or dry camping?
If you are off-grid more than 30 days a year, buy the tankless unit. The endless hot water and propane efficiency will pay off fast. If you are at full hookups 90 percent of the time and you rarely run out of hot water with your current tank, you probably do not need it. The cost and installation hassle are not worth it for the space savings.
Go check your last 12 months of trips right now. Count the days you spent without hookups. Then decide.
We were dry camping about 60 days a year when we made the switch, and it was absolutely the right call. If we were mostly at RV parks with full hookups, we probably would have lived with the tank system and saved the $850.
But we are not going back. The best tankless water heater for motorhome use is the one you actually install and start using, because once you stop negotiating shower order and start turning on the tap whenever you want hot water, you realize how much mental energy you were wasting on something that should have been simple all along. That night outside Moab when we all stood there covered in dust, arguing about who got to shower first, feels like a long time ago now.
