Tankless Water Heaters
Best Natural Gas Outdoor Tankless Water Heater (2026): 4 Picks Compared
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For natural gas outdoor tankless water heating, the Vancepic Best Overall leads with 8.5 GPM and 190,000 BTU for 4-6 outlet points, plus an LED temperature control panel. The Rheem delivers the highest flow here at 9.5 GPM, while the Westinghouse covers 3-5 fixtures at 8.1 GPM.
Starting out? See the main guide: Best Tankless Water Heater
Top picks at a glance
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Best OverallVancepic Tankless Water Heater Natural Gas9.8 View on Amazon -
9.5 View on Amazon -
Highest Flow RateRheem RTG Series 9.5 GPM Natural Gas9.4 View on Amazon -
9.2 View on Amazon
Compare the specs
Ranked on flow rate, temperature control from each listing, plus how many buyers have rated it. A dash (—) means we could not confirm that figure from the listing.
| Pick | Flow rate | Fuel | Temperature control | Weight | Warranty |
|---|---|---|---|---|---|
| 1. Vancepic Tankless Water Heater Natural Gas | 8.5 GPM | Natural Gas | Yes | 49 lb | 2-year |
| 2. Ranein Natural Gas Tankless Water Heater | 8.5 GPM | Natural Gas | — | 44 lb | — |
| 3. Rheem RTG Series 9.5 GPM Natural Gas | 9.5 GPM | Natural Gas | Yes | 39.25 lb | 5-year |
| 4. Westinghouse Gas Tankless Water Heater Outdoor | 8.1 GPM | Natural Gas | Yes | 42 lb | 2-year |
Vancepic Tankless Water Heater Natural Gas
It delivers 8.5 GPM with 190,000 BTU for 4-6 outlet points, plus an LED temperature control panel and a 2-year warranty.
- Flow rate: 8.5 GPM
- Fuel: Natural Gas
- Temperature control
- 2-year warranty stated
Good for
- Households needing hot water at 4-6 outlet points
- Buyers who want an LED temperature control panel
Skip it if
- You need flow above 8.5 GPM
- Your home sits above 2,000 feet
It measures 24.3 inches long, 15.1 inches wide and 8.1 inches high, with standard 3/4-inch NPT water inlet fittings and gas inlets. The blower adjusts its speed with external wind pressure and water temperature. It has anti-freeze protection and a 2-year warranty.
Ranein Natural Gas Tankless Water Heater
It delivers 8.5 GPM with 190,000 BTU for 4-6 outlet points, with anti-freeze protection and an LED control panel.
- Flow rate: 8.5 GPM
- Fuel: Natural Gas
Good for
- Households needing hot water at 4-6 outlet points
- Buyers who want an LED control panel
Skip it if
- You need flow above 8.5 GPM
- Your home sits above 2,000 feet
It measures 24.3 inches long, 15.1 inches wide and 8.1 inches high. The blower adjusts its speed with external wind pressure and water temperature. It has anti-freeze protection and standard 3/4-inch G water inlet fittings and gas inlets. In cold weather after long non-use, opening the pressure relief valve drains remaining water.
Rheem RTG Series 9.5 GPM Natural Gas
It delivers 9.5 GPM at a 35°F temperature rise with 199,900 BTU/hr output and a digital LED temperature control panel.
- Flow rate: 9.5 GPM, the highest here
- Fuel: Natural Gas
- Temperature control
- 5-year warranty stated
- 39.25 lb, the lightest here
Good for
- Large families needing hot water for 3-4 simultaneous showers
- Buyers who want a digital LED temperature control panel
Skip it if
- You need flow above 9.5 GPM
- You need more than 3-4 simultaneous showers
It delivers 9.5 GPM at a 35°F temperature rise with 199,900 BTU/hr output and a 0.82 Uniform Energy Factor. The digital LED temperature control panel adjusts in ±1°F steps, with freeze protection and flame failure protection built in. It is CSA certified, includes mounting hardware, and carries a 5-year warranty. It supports wall mounting by a qualified installer.
Westinghouse Gas Tankless Water Heater Outdoor
It delivers 8.1 GPM with 180,000 BTU for 3-5 fixtures, with ±1°F temperature stability and a 2-year warranty.
- Flow rate: 8.1 GPM
- Fuel: Natural Gas
- Temperature control
- 2-year warranty stated
Good for
- Households running 3-5 fixtures at once
- Buyers who want ±1°F temperature stability
Skip it if
- You need flow above 8.1 GPM
- You need more than 3-5 fixtures at once
It delivers up to 8.1 GPM with 180,000 BTU and a 95–158°F range, holding temperature within ±1°F. It is CSA certified, with freeze protection and a variable-speed combustion fan. It connects to standard 3/4-inch NPT residential plumbing and carries a 2-year warranty.
How to choose
Match flow rate to outlet points
A flow rate in GPM says how much hot water the unit delivers per minute. Compare that figure with how many outlets run at once: the Vancepic and Ranein give 8.5 GPM for 4-6 outlet points, the Rheem gives 9.5 GPM at a 35°F temperature rise for 3-4 simultaneous showers, and the Westinghouse gives 8.1 GPM for 3-5 fixtures. Pick the figure that covers the outlets in the home.
Temperature control and stability
A temperature control panel lets the unit hold a set temperature instead of firing at one level. The Vancepic has an LED temperature control panel. The Rheem has a digital LED panel with ±1°F adjustments. The Westinghouse holds temperature within ±1°F through self-modulating gas and water flow.
Outdoor setup and freeze protection
The Vancepic, Ranein and Westinghouse install outdoors. The Rheem supports wall mounting by a qualified installer. Freeze protection appears on the Vancepic, Ranein, Rheem and Westinghouse. In cold weather with long non-use, opening the pressure relief valve drains remaining water for the Vancepic and Ranein, and both are not recommended above 2,000 feet.
FAQ
What flow rate suits a home with several bathrooms?
Compare GPM with simultaneous use. The Rheem delivers 9.5 GPM for 3-4 simultaneous showers, the Vancepic and Ranein deliver 8.5 GPM for 4-6 outlet points, and the Westinghouse delivers 8.1 GPM for 3-5 fixtures.
Do these outdoor heaters need professional installation?
The Rheem supports wall mounting by a qualified installer, and professional installation is required for the Rheem unit.
Which heaters carry a stated warranty?
The Vancepic carries a 2-year warranty, the Rheem carries a 5-year warranty, and the Westinghouse carries a 2-year warranty.
What does freeze protection do on these heaters?
On these heaters, freeze protection prevents the water heater from freezing and cracking internally. The Vancepic, Ranein, Rheem and Westinghouse all include freeze protection.
