110 Volt vs Propane RV Tankless Water Heaters: How to Pick the Best One for Your Rig and Power
The best 110 volt tankless water heater for RV use is usually a small 120V electric unit that serves one sink. Propane tankless heaters carry showers. Heating water instantly takes a lot of power, and a standard RV circuit cannot supply it.
Many RVers hope for a plug-in heater that delivers endless hot showers. This article compares 120V electric and propane models using maker data. It adds a simple temperature-rise check, a buying checklist, and backup power plans for camping without shore power. Here, 110 volt and 120V mean the same household voltage.
110/120V Electric vs Propane RV Tankless Water Heaters: The Real Difference
The two types look alike on a spec sheet. Their heat comes from very different places.
Any RV propane water heater tankless model burns gas for heat. Its electrical need is small and depends on the design. A fixed unit such as the Truma AquaGo comfort uses 12V DC for its controls. A portable unit such as the Eccotemp L5 lights with two D-cell batteries. A 120V electric tankless heater makes all its heat from electricity. That limits how much water it can warm at once.
Maker data shows the gap clearly.
Example (maker data) | Heat source | Heat output | Electrical need | Flow notes |
Truma AquaGo comfort | LP gas (propane) | 20,000 to 60,000 BTU/h | 12V DC; power input under 2.5A; standby under 0.045A | Burner starts above about 0.4 gpm; outlet about 120°F |
EcoSmart POU 3.5 | 120V electric | 3.5 kW (about 11,942 BTU/h, converted) | 29A; one dedicated 30A single-pole breaker; 10 AWG wire | One low-flow faucet such as a small sink; activates at 0.25 gpm; two optional 0.35 gpm aerators |
Eccotemp L5 (portable) | LP gas (propane) | 25,000 to 37,500 BTU/h | Two D-cell batteries for ignition; pairs with a 12V pump | Up to 1.5 gpm; for temporary outdoor use |
The numbers come from Truma, EcoSmart, and Eccotemp. The BTU figure for the EcoSmart unit is a conversion, not a product claim. It is 3,500W × 3.412 BTU/h per watt, or about 11,942 BTU/h.
One point is easy to miss. The controls on a fixed propane heater that uses 12V are not electric heating. They run the controls and ignition. The gas does the heating.
The EcoSmart POU 3.5 also needs care. It is hardwired to a dedicated 30A breaker. It is not a unit to plug into an outlet.
No single model wins every case. The right pick depends on the job: a sink, a shower, or portable outdoor use.
Why 120V Units Struggle With Showers (Temperature-Rise Check)
A short formula shows what a heater can do. Temperature rise in °F is about BTU/h divided by (500 × gpm). The 500 comes from 8.33 pounds per gallon times 60 minutes.
Heater and flow | Calculation | Theoretical rise |
3.5 kW electric at 0.5 gpm | 11,942 ÷ (500 × 0.5) | About 48°F |
3.5 kW electric at 0.35 gpm (aerator) | 11,942 ÷ (500 × 0.35) | About 68°F |
60,000 BTU/h propane at 2.0 gpm | 60,000 ÷ (500 × 2.0) | About 60°F |
These are theoretical maximums before heat losses. Real output depends on inlet temperature and heater efficiency.
Here is what the first row means. With 50°F inlet water, a 48°F rise gives water near 98°F at a thin sink flow. That works for hand washing. A shower needs far more flow than a sink aerator. More flow shrinks the rise a 3.5 kW unit can deliver.
The propane row looks very different. A large burner holds a 60°F rise at a flow four times higher than the first row. That math is why even the best 110 volt tankless water heater for RV sinks stays a low-flow choice.
Tankless designs trade stored hot water for on-demand heating, and the tankless heater pros and cons apply inside an RV too.
With the difference clear, the buying checklist is short.
How to Choose the Best RV Tankless Water Heater
Start with how hot water gets used: one sink, a shower, or an outdoor rinse. Then match fuel, flow, and installation. The best tankless RV water heater for one rig can be a poor fit for another.
Retrofit units replace the old tank heater. Portable units hang outside for camp use.
Six checks cover most decisions:
Flow: Estimate the gallons per minute needed at the same time. Eccotemp suggests about 1.5 to 2.0 gpm for solo or weekend use.
Temperature rise: Cold inlet water in spring or fall needs more heat. The rise check above shows how much a heater can add.
Fuel: Propane suits showers. A 120V electric model suits a single low-flow sink, and only where the circuit and breaker allow.
Electrical need: Check the specified control or ignition supply for propane models: 12V DC or batteries, depending on the model. For electric models, check amps and breaker size.
Venting and installation: Indoor gas units need correct venting. Retrofits need the right cutout and a certified installer. Eccotemp also says propane lines and wiring belong with a certified installer.
Winterizing: Look for a simple drain and winterizing procedure in the manual. Cold-weather storage is easier when the steps are short.
Gas models are not fully free of electricity. Their gas heater electricity needs are small, but they are real.
Away from shore power, each type needs a different kind of electricity, and that decides the backup plan.
Powering an RV Water Heater Without Shore Power
A fixed propane heater such as the Truma AquaGo comfort uses 12V DC, usually supplied by the RV house battery. The portable Eccotemp L5 uses two D-cell batteries for ignition; a separate 12V pump needs its own supply. A 120V electric unit needs a large amount of power for as long as the tap runs.
A fixed propane heater powered by the RV's 12V system depends on a charged house battery. Backup power should match the heating type in use.
Fixed 12V propane models: Keep the house battery charged. Options include solar, the tow vehicle, or an AC battery charger running from a portable power station. The power station does not heat the water.
120V electric tankless: Consider battery power only for a low-wattage model. Its nameplate watts, plug, and start-up need must all fit the power station. Hardwired 30A units are not plug-in candidates.
Some rules apply to both types. A power station does not directly replace a dedicated DC battery. Neither type is guaranteed to run on one. Rated power, wiring, grounding, heating time, and hot-water demand all need checking. If a heater is over the limits, it should not be used this way. Combustion venting and professional installation rules stay the same.
Some power stations list RV-ready outputs, so a supported connection can exist. Follow both the power station manual and the RV maker’s manual. Have a qualified RV electrician confirm the connection method, grounding, and rated load. Improvised wiring and back-feeding the RV through a bypass are unsafe and should be avoided.
RVs with fixed 12V propane heaters need steady power for small electrical loads. Those include the 12V supply, lights, and phones. A portable power station can cover them and feed a battery charger. The EcoFlow DELTA 3 Max fits that kind of setup.
Electric tankless heaters pull far more power. Only a low-wattage 120V model whose plug and rating fit comes into play. That case calls for more output and capacity. The EcoFlow DELTA 3 Ultra Plus is built for it.
The two products split the job. The EcoFlow DELTA 3 Max can support rigs with a fixed 12V propane tankless heater. It runs a suitably sized external AC battery charger that keeps the 12V supply topped up. It also handles lights, phones, and other everyday loads.
The EcoFlow DELTA 3 Ultra Plus is the one to consider for a low-wattage 120V electric tankless model. That holds only when the heater's nameplate watts, plug, and start-up needs all fit. Neither unit heats water by itself. Neither replaces the heater's own power supply.
Labeled Estimates
The values below are examples. A charger's label shows its real draw. The 3,500W row only shows the energy math. The EcoSmart POU 3.5 is hardwired, so it is not a plug-in load. The 0.85 factor is an assumed conversion efficiency. Battery power does not make hot water endless, and the details of running heaters from batteries depend on each heater's label.
Setup (example values) | Calculation | Estimate |
EcoFlow DELTA 3 Max (2048Wh): AC battery charger drawing 150W + lights and phones 30W = 180W | 2,048Wh × 0.85 ÷ 180W | About 9.7 hours |
Energy for one 10-minute run of a 3,500W electric heater | 3,500W × 10 ÷ 60 | About 583Wh |
EcoFlow DELTA 3 Ultra Plus (3072Wh): number of 10-minute runs at 3,500W, if the heater's plug and rating fit | 3,072Wh × 0.85 ÷ 583Wh | About 4.5 runs |
Whatever the heater and power source, installation and safety rules come first.
Installation and Safety for RV Tankless Water Heaters
A tankless heater combines water, high heat, and either gas or high current in a small space. Follow the maker's installation manual. Use certified installers for gas and electrical work.
Carbon monoxide has no smell or color, so carbon monoxide basics matter before the first trip. The U.S. Consumer Product Safety Commission notes that fuel-burning appliances can produce the gas if they are installed incorrectly, poorly maintained, blocked, or misused. Details are in its winter safety release.
Gas units: Install with the maker's vent kit. Never block vents.
Yearly inspection: CPSC advises a professional inspection of fuel-burning systems, including water heaters, each year.
CO alarms: Keep working alarms and test them every month, as CPSC advises. In an RV, choose alarms listed for RV use.
Portable propane units: Models such as the Eccotemp L5 are made for temporary outdoor installation. Never run one inside the RV or a tent.
Electric units: Use a dedicated circuit, plus the breaker and wire size the maker lists. An electrician should do the install.
The last step is using less hot water, which helps every heater and every battery.
Ways to Get More From Less Hot Water in an RV
Smaller hot-water demand means less propane, less battery drain, and a better chance a small heater keeps up. The best RV hot water heater still works harder when several taps run at once. Habits help every model.
Low-flow shower head: It trims the gallons that need heating. Turning the water off while lathering trims them further.
Insulated hot-water lines: Wrapping exposed lines cuts heat loss between the heater and the tap.
One hot tap at a time. Running a single tap keeps flow within what the heater can warm.
Scheduled descaling: Descale tankless units on the maker's schedule to keep heat transfer up.
Many RV shower habits cost nothing and trim demand.
Conclusion
A small 110-volt electric tankless water heater is primarily a single-sink option in an RV. Propane models use gas for heat, but their electrical supplies vary: fixed models may use 12V DC, while the portable Eccotemp L5 uses two D-cell batteries for ignition.
Before selecting a unit, calculate the required flow rate and temperature rise, verify the heater's specified electrical supply and current draw, and hire certified installers to complete all gas and electrical work.
To maintain an off-grid power supply, pair propane-based setups with the EcoFlow DELTA 3 Max to run everyday loads and charging gear. For lower-wattage 120V electric heaters operating within strict power limits, use the EcoFlow DELTA 3 Ultra Plus to cover electrical demand seamlessly.
FAQs
Is a 110 volt tankless water heater good enough for an RV shower?
Usually not. A 3.5 kW unit gives about a 48°F rise at 0.5 gpm (estimate), which suits a small sink. Showers need far more flow, which is why most RV tankless heaters use propane. Cold inlet water in spring or fall widens the gap further.
Does a propane tankless RV water heater need electricity?
Yes, a little. The Truma AquaGo comfort, for example, runs on 12V DC with power input under 2.5A for its controls. Standby current is under 0.045A, and propane does the heating. The house battery usually supplies that 12V.
Can I plug a 120V tankless water heater into a regular outlet?
Many cannot. The EcoSmart POU 3.5 draws 29A and needs a dedicated 30A breaker, so it is hardwired. A standard outlet cannot supply that load. Check the maker's electrical requirements before buying any model, since amps and breaker size vary by unit.
Can a portable power station run an RV tankless water heater?
For a fixed 12V propane heater, it can power a suitable external battery charger and run everyday loads. A 120V electric model works only if it is low wattage, its plug and rating fit, and only for a limited time. Check the heater's label for watts and start-up needs first.
Do I need a CO alarm with a propane tankless water heater?
Yes. Fuel-burning appliances can produce carbon monoxide if venting is blocked or the unit is misused. Keep a working CO alarm and test it monthly. In an RV, pick one listed for RV use, and replace it as the maker advises.
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