Outdoor natural gas tankless water heaters provide an energy-efficient way to enjoy continuous hot water without the bulk of traditional tanks. They save space, reduce standby heat loss, and offer on-demand heating, ideal for households looking to balance comfort and utility costs. Below is a summary table featuring the selected top-rated units tested for performance, durability, and value.
| Product | Brand | Max Flow Rate (GPM) | BTU |
|---|---|---|---|
| Rheem RTG-70XLN-3 | Rheem | 7.0 | Not Specified |
| Ranein Outdoor Max 5.3 GPM | Ranein | 5.3 | 130,000 |
| Rinnai V53DeN | Rinnai | 5.3 | Not Specified |
| FOGATTI Instagas Comfort 180S | FOGATTI | 8.1 | 180,000 |
| Rinnai RX199iN Condensing | Rinnai | 11.1 | 199,000 |
Rheem RTG-70XLN-3 Outdoor Tankless Natural Gas Water Heater
The Rheem RTG-70XLN-3 delivers continuous hot water sufficient for whole-house use, supporting simultaneous appliances like showers and dishwashers. Its high-efficiency operation ensures the heater runs only when needed, conserving energy and reducing water waste with a special water-saving setting that can save up to 1,100 gallons annually.
This unit’s design emphasizes comfort and resource savings, optimizing both energy costs and water usage. Being non-condensing and outdoor-rated, it is built to withstand external conditions while providing reliable hot water on demand.
Ranein Outdoor Max 5.3 GPM Natural Gas Tankless Water Heater
The Ranein Tankless Water Heater offers immediate hot water with no preheating delay and supports a modest 5.3 GPM flow rate. It features a large-powered blower that adjusts automatically to external wind and water temperature changes, ensuring secure combustion and enhanced safety without smoke backflow.
Its compact size simplifies installation using standard 1/2″ NPT water inlets and 3/4″ NPT air inlets. Designed with user convenience and safety in mind, it provides low noise operation and long service life, making it suitable for outdoor environments.
Rinnai V53DeN 5.3 GPM Outdoor Natural Gas Tankless Water Heater
The Rinnai V53DeN guarantees unlimited hot water with a flow rate capable of serving up to four appliances simultaneously. It’s designed for energy conservation by heating water only when needed, which helps reduce utility bills and environmental impact.
This outdoor unit also offers peace of mind with a 10-year heat exchanger warranty, reflecting the brand’s commitment to durability and reliability. Its compact footprint is ideal for efficient outdoor installation while maintaining easy servicing.
FOGATTI Instagas Comfort 180S Series Outdoor Natural Gas Tankless Water Heater
The FOGATTI Instagas Comfort 180S stands out with a high BTU rating of 180,000 and an impressive 8.1 GPM flow rate, delivering instant hot water for multiple simultaneous outlets such as showers and sinks. Its advanced technology keeps water temperature within ±1°F for consistent comfort.
Designed explicitly for outdoor durability, it includes a bottom-mounted fan to prevent smoke backflow and a remote control panel for convenient indoor operation. The four-stage combustion system maximizes efficiency across all seasons.
Rinnai RX199iN Condensing Smart Sense Natural Gas Tankless Water Heater
The Rinnai RX199iN offers ultra-high capacity with up to 11.1 GPM and a powerful 199,000 BTU output, supporting up to seven fixtures simultaneously. This versatile unit installs both indoors and outdoors and handles natural gas or propane fuels with smart Sensory gas control.
Its condensing technology ensures a UEF of .98, reflecting top-tier energy efficiency. Features include an easy-to-use interface, Quick Flush maintenance, and optional WiFi compatibility for remote monitoring and control, making it a smart choice for modern homes.
Buying Guide: Choosing the Best Outdoor Natural Gas Tankless Water Heater
Flow Rate and Capacity
Select a unit based on peak hot water demand, measured in gallons per minute (GPM). Larger homes or multiple simultaneous users require higher GPM to avoid cold water interruptions.
BTU Rating and Efficiency
BTUs indicate heating capacity; higher BTUs provide faster heating and support more outlets. Look for high thermal efficiency to reduce fuel consumption and energy bills.
Installation Location and Durability
Outdoor models must be weather-resistant with protections against wind, rain, freezing, and sun exposure. Confirm the unit is certified for outdoor use and matches your climate zone requirements.
Fuel Type Compatibility
Ensure the heater supports your available fuel source—natural gas or propane. Some models offer dual-fuel capability, increasing installation flexibility.
Temperature Control and Safety Features
Precision temperature control maintains comfortable water temperatures without fluctuations. Safety features like flame failure protection, overheat protection, dry combustion prevention, and freeze protection are critical for reliable outdoor performance.
Size and Installation Requirements
Compact designs ease installation in limited spaces. Check connection sizes for water and gas inlets (e.g., 1/2″ NPT), venting needs, and available mounting options to ensure compatibility.
Warranty and Support
Look for brands offering substantial warranty periods on heat exchangers and parts. Responsive customer service and installation support add peace of mind during ownership.
Additional Features
Remote controls, smart home compatibility, and ease of maintenance enhance user experience and operational convenience for modern households.