Best RV Tankless Water Heaters
Compare RV-rated propane tankless heaters by BTU input, flow limitations, cutout size, venting and real retrofit requirements.
Compare Current OptionsReplacing a six-gallon tank does not simply mean buying a unit with a larger advertised GPM number. A tankless heater has to fit an RV wall opening, vent combustion gases safely and raise incoming water to shower temperature while water is flowing. This comparison focuses on four distinct RV propane models, separating verified specifications from assumptions about real-world performance.
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01 RV tankless heater shortlist
These four RV-rated choices cover two Suburban heat-input classes and two Fogatti output configurations.
Suburban publishes a 60,000 BTU/h input rating, a 0.7 GPM minimum activation flow, a 12V electrical requirement and a 131°F maximum outlet setting for its ST-60.
The ST-42 shares the ST series installation concept and listed minimum activation flow, but its maximum heat input is 42,000 BTU/h rather than 60,000.
Fogatti lists a 55,000 BTU/h heater with up to 2.9 GPM, selectable 95–123°F outlet temperature and a minimum 13-by-13-inch cutout.
Fogatti differentiates its 9 Pro with a 66,000 BTU/h input class, up to 3.6 GPM published flow and an integrated mixing tank.
02 Compare heat input and fitment
BTU/h measures heat input; advertised maximum GPM may be measured under conditions unlike a cold-weather RV shower.
| Exact model | Heat input | Published distinction | Best-fit scenario |
|---|---|---|---|
| Suburban ST-60 | 60,000 BTU/h input | 12V DC · 0.7 GPM minimum activation | Higher-input RV retrofit |
| Suburban ST-42 | 42,000 BTU/h input | 12V DC · 0.7 GPM minimum activation | Lower-input Suburban alternative |
| Fogatti InstaShower 8 Plus | 55,000 BTU/h input | Up to 2.9 GPM claimed · 12V DC | Mid-size family shower option |
| Fogatti InstaShower 9 Pro | 66,000 BTU/h input | Up to 3.6 GPM claimed · mixing tank | Higher-flow model with mixing tank |
03 Four RV-rated heater options
Manufacturer specifications are cited for each model; this guide does not claim hands-on installation, performance testing or a measured ranking.
Suburban ST-60
Suburban publishes a 60,000 BTU/h input rating, a 0.7 GPM minimum activation flow, a 12V electrical requirement and a 131°F maximum outlet setting for its ST-60.
Best fit: RVs whose hot-water demand and certified installation opening justify the higher heat-input class.
RVs whose hot-water demand and certified installation opening justify the higher heat-input class.
Confirm the full vent, access-door, LP gas, wiring and water connection arrangement with an authorized installer; nominal input is not a promised GPM at a given temperature rise.
Manufacturer source: Product specification or official series comparison. Figures are manufacturer-published, not independent test results.
Check PriceSuburban ST-42
The ST-42 shares the ST series installation concept and listed minimum activation flow, but its maximum heat input is 42,000 BTU/h rather than 60,000.
Best fit: Smaller RVs with compatible openings and lower expected simultaneous hot-water demand.
Smaller RVs with compatible openings and lower expected simultaneous hot-water demand.
A lower input rating can limit available hot-water flow in cold inlet-water conditions; do not assume the same shower performance as the ST-60.
Manufacturer source: Product specification or official series comparison. Figures are manufacturer-published, not independent test results.
Check PriceFogatti InstaShower 8 Plus
Fogatti lists a 55,000 BTU/h heater with up to 2.9 GPM, selectable 95–123°F outlet temperature and a minimum 13-by-13-inch cutout.
Best fit: Mid-size travel trailers or Class C RVs seeking a manufacturer-listed flow benchmark and compatible exterior door kit.
Mid-size travel trailers or Class C RVs seeking a manufacturer-listed flow benchmark and compatible exterior door kit.
The up-to GPM figure depends on inlet temperature and required temperature rise. Select a door size that covers the actual exterior opening.
Manufacturer source: Product specification or official series comparison. Figures are manufacturer-published, not independent test results.
Check PriceFogatti InstaShower 9 Pro
Fogatti differentiates its 9 Pro with a 66,000 BTU/h input class, up to 3.6 GPM published flow and an integrated mixing tank.
Best fit: Larger RVs that can support its installation requirements and need more hot-water output margin.
Larger RVs that can support its installation requirements and need more hot-water output margin.
Do not read the maximum GPM as guaranteed in winter; verify LP capacity, minimum flow, access door and exterior clearances.
Manufacturer source: Product specification or official series comparison. Figures are manufacturer-published, not independent test results.
Check Price04 Seven critical retrofit checks
LP gas and combustion venting create serious safety hazards. Installation and servicing should be performed by a qualified RV technician.
- Confirm RV-specific certification: Choose an RV-rated, externally vented appliance; a household or portable outdoor shower heater is not an interchangeable RV installation.
- Measure the existing rough opening and exterior door: Record the cutout, wall depth, framing, door coverage and vent path. A nominal 13-by-13-inch cutout does not guarantee a drop-in retrofit.
- Calculate hot-water output from inlet temperature: BTU input and maximum GPM cannot be compared without the required temperature rise. Cold campground water can sharply reduce useful shower flow.
- Check propane supply and combustion requirements: A qualified RV technician should verify LP regulator capacity, gas piping, combustion air, exhaust clearances and appliance-specific venting.
- Verify 12V DC power and controls: Confirm the model-specific fuse, wiring, controller routing and supply stability. These propane heaters still need DC power for electronics and ignition.
- Check minimum activation flow and water pressure: Low-flow fixtures, pump cycling or restricted plumbing can prevent reliable ignition. Match operating requirements to the RV pump and city-water setup.
- Plan freeze protection and professional commissioning: Powered freeze protection may stop working without electricity or propane. Follow the manufacturer winterization procedure and have a qualified installer leak-test and commission the unit.
05 Choose for your temperature rise
Cold-water camping: evaluate required temperature rise before comparing maximum GPM claims. A heater must add more energy per gallon when inlet water is colder, reducing achievable flow at a given output temperature.
Smaller RV with modest demand: Suburban ST-42 offers a 42,000 BTU/h class; verify that its heat input and activation flow meet your actual fixtures.
Higher heat input: Suburban ST-60 publishes 60,000 BTU/h, with a 0.7 GPM minimum activation flow for the ST series. The Fogatti 9 Pro is rated at 66,000 BTU/h with a mixing tank, but retrofit fit still comes first.
Water delivery problems: If hot-water flow is inconsistent because of the freshwater pump, start with RV water pump selection. If pressure varies only on campground hookups, compare RV pressure regulators.
06 Frequently asked questions
Are RV tankless water heaters truly unlimited?
They heat water continuously while adequate propane, 12V power and water flow are available. Their output is still limited by heat input and the inlet-water temperature.
How many GPM do I need for an RV shower?
Start with the actual showerhead flow and cold-water temperature. Published maximum GPM is not necessarily the hot-water flow achievable at the temperature rise you need.
Can I install a residential tankless heater in an RV?
Do not substitute a residential or outdoor portable unit for an RV-certified heater. Venting, vibration, combustion and installation standards differ.
Will a tankless heater work with my 12V RV water pump?
It may, if the pump can maintain the heater’s required operating pressure and minimum activation flow. Verify the exact specifications for both devices.
Does tankless save propane compared with a tank heater?
It avoids continuously maintaining a storage tank at temperature, but actual propane use depends on hot-water volume, temperature rise, burner efficiency and habits.
Do tankless RV heaters need winterizing?
Yes. Some models provide powered freeze protection, but protection has operating conditions and does not replace the manufacturer’s winterization instructions.
07 Prioritize certified RV fitment
The strongest choice is not automatically the heater with the largest input or maximum-flow claim. Verify the existing wall opening, approved exhaust path, LP and 12V requirements, activation flow and realistic temperature rise before committing. Have a qualified RV technician handle installation and commissioning.