Best Outdoor Tankless Natural Gas Water Heaters for Efficient Hot Water 2025
If you’re seeking a reliable and energy-efficient solution for providing continuous hot water outdoors, outdoor tankless natural gas water heaters are an excellent choice. These units deliver hot water on demand without storing it, saving energy and space while ensuring you never run out of hot water. Below is a summary table highlighting the top models, followed by detailed reviews of the best outdoor tankless natural gas water heaters available on Amazon.
| Model | Brand | Flow Rate (GPM) | BTU | Installation |
|---|---|---|---|---|
| Rheem RTG-70XLN-3 High Efficiency | Rheem | 7.0 | Not Specified | Outdoor |
| Ranein Tankless Water Heater | Ranein | 5.3 | 130,000 | Outdoor |
| Rinnai V53DeN Natural Gas Heater | Rinnai | 5.3 | Not Specified | Outdoor |
| FOGATTI Instagas Comfort 180S Series | FOGATTI | 8.1 | 180,000 | Outdoor |
| Rinnai RX199iN Condensing Smart Sense | Rinnai | 11.1 | 199,000 | Indoor/Outdoor |
Rheem RTG-70XLN-3 High Efficiency Outdoor Tankless Water Heater
The Rheem RTG-70XLN-3 is a high-efficiency, non-condensing tankless water heater designed for outdoor installation. It offers 7.0 gallons per minute (GPM), providing continuous hot water to satisfy the needs of an entire household, even when multiple fixtures such as showers and dishwashers run simultaneously. This unit operates only when hot water is required, improving energy efficiency and reducing costs. Additionally, it features a water-saving setting capable of conserving up to 1,100 gallons annually. The gray, weather-resistant design is ideal for outdoor use, making it a practical and efficient choice for residential applications.
Ranein Natural Gas Outdoor Tankless Water Heater, 5.3 GPM
The Ranein 5.3 GPM tankless water heater features a powerful 130,000 BTU burner that instantly heats water on demand without preheating wait. It employs an advanced blower fan system located underneath the unit to ensure safe combustion by preventing smoke backflow. This fan adjusts speed depending on wind pressure and water temperature changes, assuring efficient and reliable operation even in outdoor environments.
Compact and easy to install, it uses standard 1/2″ NPT water inlet fittings and 3/4″ NPT air inlets, making it suitable for quick assembly. The low noise and durable construction, complemented by customer support for installation, make the Ranein model suitable for users seeking a safe and hassle-free outdoor natural gas water heater.
Rinnai V53DeN Natural Gas Tankless Outdoor Water Heater
The Rinnai V53DeN provides unlimited hot water with a flow rate of 5.3 GPM, capable of supporting up to four appliances concurrently. It features an energy-efficient gas heating system that activates only when water is needed, reducing utility costs and environmental impact. The heater is compact and built specifically for outdoor installation, enhancing space management around your home.
This model is supported by a comprehensive 10-year warranty on the heat exchanger, underscoring its durability and long-lasting performance. The simple yet effective design is ideal for homeowners seeking a balance between energy savings and continuous hot water supply.
FOGATTI Natural Gas Tankless Water Heater, 8.1 GPM Outdoor Installation
The FOGATTI Instagas Comfort 180S Series is an exceptional outdoor tankless water heater delivering up to 8.1 GPM powered by a 180,000 BTU burner. It instantly provides hot water to multiple outlets, supporting 3 to 5 fixtures, including showers and sinks, without delay.
This model is engineered for outdoor durability, featuring a bottom-mounted fan to prevent smoke backflow and ensure stable combustion. Its remote control panel allows for convenient indoor operation. With advanced water servo technology, it maintains precise temperature control within ±1℉, ensuring consistent comfort across all seasons.
Rinnai RX199iN Condensing Smart Sense Tankless Water Heater
The Rinnai RX199iN is a versatile, high-capacity condensing tankless water heater capable of both indoor and outdoor installation. This powerful unit provides up to 11.1 GPM to supply up to seven fixtures simultaneously with hot water.
Powered by 199,000 BTU and controlled via a Smart Sense gas system, it can use either natural gas or propane. This model includes advanced features such as WiFi compatibility (with an optional Controlr module), a user-friendly interface, and a Quick Flush feature to simplify maintenance. Its high energy efficiency ratio (UEF 0.98) supports lower energy consumption and utility bills.
Buying Guide: Choosing the Best Outdoor Tankless Natural Gas Water Heater
Flow Rate (GPM)
The flow rate, measured in gallons per minute, indicates the amount of hot water the unit can provide simultaneously. Choose a heater with a GPM rating that matches your household’s peak usage needs—typically 5-8 GPM for average families, and higher for larger homes with multiple fixtures.
BTU Rating
Higher BTU ratings translate to a faster heating capability and higher output. For outdoor units, BTUs typically range from 120,000 to 199,000. Consider your climate and the number of appliances requiring hot water when selecting a BTU level.
Installation Location
Ensure the model is designed for outdoor installation and features weatherproof materials such as corrosion-resistant casing, stainless steel vents, and waterproof ratings (e.g., IPX4). Some units also offer dual indoor/outdoor versatility for installation flexibility.
Energy Efficiency
Look for models with high energy efficiency ratings or certifications. Tankless heaters only heat water when in use, reducing waste. Features like condensing technology and programmable thermostats improve savings further.
Safety Features
Important safety measures include flame failure protection, freeze protection, overheat prevention, and combustion exhaust ventilation designs. Models with fans or blowers to prevent smoke backflow enhance safety in windy outdoor conditions.
Maintenance and Warranty
Choose heaters with accessible designs for easy maintenance, including flushing and filter cleaning. A substantial manufacturer warranty on heat exchangers and parts offers long-term peace of mind.
Additional Functionality
Advanced features like remote control panels, smart home WiFi compatibility, and precise temperature control can improve convenience and user experience.