Choosing the best outdoor instant hot water heater means matching its fuel type and flow rate to your home, then checking that it can handle your cold-weather conditions. The models below heat water on demand and mount outside, but they differ in capacity, controls, freeze protection, and installation needs. Use the comparison table to narrow your options, and confirm the fuel and installation requirements before you buy.
Table of Contents
Quick Comparison
| Product | Fuel | Maximum flow | Heating capacity | Standout feature |
|---|---|---|---|---|
| OEVANT Outdoor Tankless Water Heater | Propane | 5.3 GPM | 130,000 BTU | Remote control and included vent pipe |
| Westinghouse Outdoor Tankless Water Heater | Propane | 5.1 GPM | 120,000 BTU | Low-flow activation and wired digital controller |
| Rheem RTG Series 7.0 GPM Tankless Water Heater | Fuel type needs verification | 7.0 GPM | 160,000 BTU | High listed flow capacity and long heat-exchanger warranty |
| Orbek Indoor/Outdoor Tankless Water Heater | Natural gas | 5.1 GPM | 120,000 BTU | Wi-Fi and app controls |
| FOGATTI Outdoor Propane Tankless Water Heater | Propane | 5.1 GPM | 120,000 BTU | Indoor remote control and low-pressure compatibility |
Our Picks: Best Outdoor Instant Hot Water Heater reviews
OEVANT: High-Capacity Propane Heater with Remote Control
The OEVANT is a propane-powered outdoor tankless heater rated for up to 5.3 GPM and 130,000 BTU. Its listed capacity is a little higher than the Westinghouse and FOGATTI models, which may be useful if your household runs several hot-water taps at once. Actual output at your desired temperature depends on incoming water temperature and how much hot water is being used.
Convenience is a focus here: the heater includes an indoor remote control, standard 3/4-inch water and gas connections, and a vent pipe in the kit. The description also lists an oxygen-free copper heat exchanger, stainless-steel burner, electronic freeze protection, and multiple safety features. Those features are appealing, but freeze protection for a heater does not automatically protect exposed pipes or plumbing around it.
One practical caution: the supplied product information marks this model as unavailable. Check the listing and confirm that the unit can be purchased before planning a project around it. If it is available, it may suit a propane home looking for a compact outdoor unit with more listed flow than the other mid-capacity options here.
Pros:
- Highest listed flow rate among the propane models in this roundup
- Indoor remote control for adjusting settings
- Vent pipe is listed as included
- Includes electronic freeze protection and several safety safeguards
Cons:
- Product data marks the listing as unavailable
- External plumbing still needs suitable protection in freezing conditions
Verdict: Consider the OEVANT if its listing becomes available and you want a higher-capacity propane model with remote operation, but verify stock and installation details first.
Westinghouse: Propane Heater with Low-Flow Activation
This Westinghouse model is an outdoor propane heater rated for 5.1 GPM and 120,000 BTU. Its listed low-flow activation point is 0.53 GPM, and it is designed to start at a minimum water pressure of 15 PSI. Those details could make it worth considering if your plumbing has modest pressure or if a low-flow tap is part of your regular routine.
A wired digital controller comes with the unit, with a listed adjustment range from 95°F to 158°F. The manufacturer describes temperature stability within ±1°F and says the heater can support two to four fixtures, depending on use. It also lists a fan intended to help limit wind-related backdraft and self-heating freeze protection for the heater.
Cold-weather protection has limits: the product information says the unit needs continuous power for its freeze-protection function and advises fully draining it if temperatures fall below 32°F without power. It also notes that external pipes need separate insulation. That makes winter planning especially important if the heater will be installed in a cold or exposed location.
Pros:
- Low listed activation flow and 15 PSI minimum pressure
- Wired controller with a broad temperature adjustment range
- Outdoor design includes wind and freeze-protection features
- CSA/ANSI certification is listed in the product description
Cons:
- Freeze protection depends on continuous power
- External pipes need separate insulation or winter protection
Verdict: The Westinghouse is a strong choice for propane users who value low-flow activation and a wired controller, provided they have a plan for winter protection and power outages.
Rheem RTG Series: Highest Listed Flow for Larger Homes
The Rheem RTG Series stands out on paper with a listed maximum flow of 7.0 GPM at a 35°F temperature rise and an output of 160,000 BTU per hour. Its description says it can support two to three simultaneous showers, making it the highest-capacity option in this group for households with heavier hot-water needs.
The unit is described as an outdoor wall-mounted, non-condensing heater with built-in freeze protection, flame-failure protection, and a digital temperature control. Rheem also lists a 15-year heat-exchanger warranty and a five-year parts warranty. Professional installation is specified, so plan for qualified help rather than treating this as a simple plug-in appliance.
There is an important detail to confirm before ordering: the product title identifies it as liquid propane, while the supplied description calls it a natural-gas heater in one place. Because fuel types are not interchangeable, verify the exact model and fuel connection with the seller and installer. The description also calls it outdoor equipment while including a conflicting reference to indoor installation, so confirm the approved placement as well.
Pros:
- Highest listed flow rate and BTU output in this comparison
- Designed for outdoor wall mounting
- Built-in freeze and flame-failure protection are listed
- Long heat-exchanger warranty compared with the other options here
Cons:
- Supplied information conflicts on fuel type and installation description
- Professional installation is required
Verdict: The Rheem may suit a larger household that needs more listed capacity, but only choose it after confirming the exact fuel type, installation location, and model specifications.
Orbek: Natural-Gas Heater with App and Voice Controls
The Orbek is listed as a natural-gas model with a maximum flow of 5.1 GPM and 120,000 BTU. Its description says it can serve two to four outlets and has a low-flow start point of 0.53 GPM. It may appeal to households that want remote access: the listed controls include Wi-Fi, an app, and Alexa voice control.
Its indoor/outdoor claim needs a closer look. For indoor installation, the description calls for the included direct-vent pipe kit. For outdoor installation, it says a weatherproof exhaust hood is sold separately. That added part may affect the total setup, so confirm what is included and what your local installation requires before choosing an outdoor location.
The compact case and listed safety protections—including safeguards against dry burning, overheating, flameout, and high water pressure—are useful considerations. Still, smart controls do not replace checking gas compatibility, required clearances, and professional installation needs. This is the only natural-gas model in the comparison, so it is not a direct substitute for the propane options.
Pros:
- App, Wi-Fi, and voice-control features are listed
- Low-flow activation point of 0.53 GPM
- Compact design with multiple listed safety protections
- Can be set up indoors or outdoors with the required equipment
Cons:
- Outdoor exhaust hood is sold separately
- Natural gas only, so it will not suit a propane-only setup
Verdict: Choose the Orbek if you have natural gas and want app-based controls, but factor in the separate outdoor hood and verify the installation requirements.
FOGATTI: Compact Propane Option with Indoor Remote
FOGATTI’s outdoor propane heater is rated for 5.1 GPM and 120,000 BTU, with the manufacturer describing it as suitable for two to four outlets. It is a mid-capacity option for a home with moderate simultaneous hot-water use. The listed operating pressure range is 15 to 150 PSI, and the unit connects to a standard 120V AC power source.
The heater includes a remote control panel for indoor adjustments, plus a copper heat exchanger and stainless-steel burner. FOGATTI lists a two-year warranty for the full unit and five years for the heat exchanger. Its description also mentions active freeze protection, but advises draining the water if temperatures drop below 5°F or if the unit will sit unused for an extended time.
Compared with the Westinghouse, FOGATTI has a similar listed flow and BTU capacity, while the Westinghouse provides more detail about low-flow activation and its wired controller. FOGATTI may be a good fit if its dimensions and remote setup suit your installation, but include winter shutdown and drainage in your maintenance plan.
Pros:
- Indoor remote control and standard 120V AC connection
- Listed for water pressure from 15 to 150 PSI
- Includes a copper heat exchanger and stainless-steel burner
- Heat-exchanger warranty is longer than the full-unit warranty
Cons:
- Requires draining in very cold weather or during extended nonuse
- Maximum listed flow is below the OEVANT and Rheem figures
Verdict: The FOGATTI is a practical propane option for a medium-size household that wants remote temperature control and is prepared to manage winter drainage.
How to Choose an Outdoor Instant Hot Water Heater
Match the fuel to your home
Start by confirming whether your home uses propane or natural gas. A heater built for one fuel should not be assumed to work with the other. Check the product label, connection requirements, and installation instructions, and have a qualified professional confirm compatibility. This is especially important for the Rheem listing, whose supplied information names both propane and natural gas.
Estimate how much hot water you use at once
Think about the fixtures that may run together, such as a shower and kitchen tap or more than one shower. Compare that demand with the heater’s rated flow, but remember that the maximum figure does not tell the whole story. A heater’s hot-water output changes with the temperature of incoming water and the temperature rise you need. Colder incoming water can reduce the amount of hot water available at a given flow.
Check activation flow and water pressure
A tankless unit must detect water flow before it starts heating. If your household uses low-flow fixtures or has older plumbing, look at the minimum activation flow and minimum pressure. The Westinghouse and Orbek list a 0.53 GPM activation point, while the FOGATTI description lists a pressure range beginning at 15 PSI. Confirm that your actual plumbing conditions fall within the unit’s requirements.
Plan for outdoor installation and venting
Outdoor placement can avoid the need for an indoor venting setup, but it still requires a suitable exterior location and correct clearances. Read the installation manual before choosing a wall or mounting spot. Some models may need extra parts for outdoor use; the Orbek description, for example, says its outdoor exhaust hood is sold separately. Verify what comes in the box and what local codes require.
Understand freeze protection
Freeze protection varies by model and may rely on the heater having continuous power. It may protect the unit’s internal waterways without protecting the water lines leading to and from it. Check the manufacturer’s cold-weather instructions, including when to insulate pipes, drain the heater, or take other steps during a power outage or extended period without use.
Compare controls and temperature settings
Consider where you want to adjust the temperature. Some models include an indoor remote or wired controller, while the Orbek description lists app and voice controls. Check whether the controller is included, how it connects, and whether the temperature range suits your household. Precise controls are useful, but they do not increase the heater’s flow capacity.
Review installation, certification, and warranty details
Gas connections, water connections, electrical power, and outdoor placement all affect installation. Check the product’s certification, warranty terms, and installation instructions before buying. A professional installer can verify fuel supply, water pressure, mounting requirements, and local code compliance. Do not rely on a product title alone when the listing details conflict.
Frequently Asked Questions
How do I choose the right flow rate?
List the hot-water fixtures you expect to use at the same time, then compare that demand with the unit’s flow rating. Also consider your incoming water temperature: colder water requires a greater temperature rise and can reduce available hot-water flow. An installer can help match the unit to your household’s actual needs.
Does an outdoor tankless heater provide hot water instantly at the tap?
The heater warms water on demand, but the hot water still has to travel through the pipes to the fixture. The wait depends in part on the distance between the heater and the tap. “Instant” describes heating without a storage tank, not necessarily immediate hot water at every faucet.
Can an outdoor tankless heater work in freezing weather?
Some models include freeze-protection features, but their effectiveness depends on the unit’s instructions and conditions such as having continuous power. Exposed pipes may need separate insulation, and some units should be drained during severe cold or long periods of nonuse. Follow the manual for the exact model.
Can I use a propane heater with natural gas?
Do not assume you can. Fuel connections and requirements differ, and a model should only be installed with the fuel type approved for that unit. Confirm the exact model and fuel with the seller and a qualified installer before ordering.
Does a higher GPM rating guarantee more hot water in every home?
No. The listed maximum flow is only one part of performance. Incoming water temperature, desired outlet temperature, water pressure, and the number of fixtures running together all affect the result. Compare ratings under similar conditions and have your expected demand assessed before choosing.
Should I hire a professional to install a gas tankless water heater?
Professional installation is a sensible choice for a gas appliance, particularly when the work involves gas lines, electrical power, mounting, or code requirements. Some product descriptions specifically call for professional installation. Follow the unit’s manual and local rules.
Final Recommendation
For a propane setup that needs low-flow activation and a wired controller, the Westinghouse offers a useful balance of capacity and controls, with clear cold-weather cautions to plan around. The Rheem has the highest listed flow, but its conflicting fuel and installation details make verification essential. For natural gas and app controls, the Orbek is worth considering if you account for its separately sold outdoor hood. Match the heater to your fuel, simultaneous hot-water demand, and winter conditions before making a final choice.
