Choosing the best RV tankless water heater means no more two-minute showers. Here’s how to pick one, fit it to your rig and keep it working on the road.
Most RV tankless units burn propane and use 12V DC for controls; they fit the standard 6- or 10-gallon water heater opening.
Check four things: cutout size, BTU and GPM, minimum activation flow and 12V power draw.
Winterize by draining the unit and following the manufacturer’s antifreeze or air blow-out instructions.
Why go tankless in an RV
A typical RV has a 6- or 10-gallon tank heater that takes time to heat and runs out quickly. An RV tankless water heater heats water on demand with propane, so hot water is ready in seconds and doesn’t run out as long as you have propane, water and power. Tankless units also save weight because there is no tank full of water.
Popular RV tankless brands
Brand
Notes
Furrion
Drop-in RV tankless units with digital controls
Girard
GSWH-2 and related models, known for adjustable temperature
Truma
AquaGo units with fast heat-up and decalcification mode
Suburban
IW series designed for RV and marine use
Check the manual for your specific model for cutout size, door options and power requirements.
How to choose
Cutout size. Measure your existing water heater opening. Most units fit the 6- or 10-gallon size; adapter frames bridge small differences.
Flow and BTU. RV units usually range from about 40,000 to 60,000 BTU and deliver around 1.5–2.5 GPM, enough for one RV shower.
Minimum activation flow. RV pumps and low-flow shower heads must reach this flow to fire the burner.
12V draw. Important when boondocking on batteries.
Cold-weather use. Look for freeze protection if you camp in winter.
RV tankless water heater installation
General steps (always follow the manual):
Turn off propane, 12V and 120V power, and drain the water system.
Remove the old water heater: disconnect gas, water and wiring, remove screws and sealant.
Fit the new unit or adapter frame in the opening, sealing it to the sidewall as instructed.
Connect propane with approved fittings and leak-test.
Connect cold inlet and hot outlet lines; add a bypass kit if not already present.
Connect 12V power (and 120V where required).
Refill, purge air from lines, then test operation and check for leaks.
If you are not comfortable with propane connections, have an RV technician do the installation.
How to winterize an RV tankless water heater
Turn off the unit, propane and power.
Open hot and cold faucets to relieve pressure.
Remove the drain plug(s) or open the drain valve and let the unit empty completely.
Set the bypass valves to bypass the water heater if you use RV antifreeze.
Follow the manufacturer’s instructions on whether to blow out lines with air, use antifreeze, or both.
Reinstall drain plugs loosely or store them as directed.
To de-winterize, flush antifreeze from the lines, close the bypass, refill the unit, purge air, then restore power and propane.
Troubleshooting on the road
No ignition: low propane, closed propane valve, or low 12V battery voltage.
Lukewarm water: flow too high for the temperature rise, or scale buildup.
Burner cycles on and off: flow near the activation threshold or a weak water pump.
The best unit fits your existing opening, delivers enough flow for your shower at the temperatures you camp in, has a low minimum activation flow, and has good dealer support. Furrion, Girard, Truma and Suburban are popular brands designed for RVs.
Can I replace my RV water heater with a tankless unit?
Yes. Most RV tankless units are designed to replace 6- or 10-gallon tank heaters in the same opening, sometimes with an adapter frame. You will need to connect propane, 12V power and water lines and check that the door and venting fit.
Is there a good 110 volt tankless water heater for an RV?
Small 110–120V electric tankless units can work for a sink but rarely provide enough heat for a comfortable shower. Propane units are the usual choice for RV showers.
Do I need to winterize an RV tankless water heater?
Yes. Any water left inside can freeze and crack the heat exchanger. Drain it fully and follow the manufacturer’s winterizing steps.
This guide is general information for U.S. homeowners, not professional advice. Gas, electrical and venting work must follow the manufacturer’s instructions and local codes, and in most areas requires a licensed plumber, electrician or gas fitter and a permit. Specifications and prices change; always confirm details on the product page and in the installation manual.
