10 Best Outdoor Tankless Water Heaters 2026 in the United States

The Rinnai RXP199iN is a highly efficient tankless water heater that can operate on either propane or natural gas, making it versatile in terms of energy source. With a flow rate of up to 11.1 gallons per minute (GPM), it can supply hot water for multiple fixtures simultaneously, which is great for larger households or outdoor uses where instant hot water is a necessity. Its BTU rating of 199,000 indicates strong heating performance.

One of its standout features is the Smart-Circ Intelligent Recirculation system, which learns your hot water usage patterns and optimizes the recirculation to save energy and reduce wait times for hot water. Additionally, the high energy efficiency rating (UEF .98) means lower operating costs over time.

Installation is an important consideration; while it requires professional installation, the Rinnai Central App offers support for setup and troubleshooting, which can ease the learning curve for users. The heater is also designed for durability and can be installed outdoors with the proper venting, making it suitable for various environments. There are a few potential drawbacks. The need for professional installation may add to the cost, especially for those who prefer DIY projects. The unit is relatively compact but weighs 58 pounds, which might be cumbersome for some to handle during installation. Additionally, while the WiFi connectivity is a modern touch, the Control-R module is sold separately, which may be an extra expense for those wanting smart home integration.

The FOGATTI Propane Tankless Water Heater is a compact and efficient choice for outdoor use, delivering a strong flow rate of up to 5.1 gallons per minute and a high heat output of 120,000 BTU. This means it can supply hot water to 2 to 4 outlets simultaneously, which suits medium-sized households well. Its design is space-saving and energy-efficient, helping reduce fuel costs while providing instant hot water on demand. The precise temperature control keeps water temperature steady within 1 degree Fahrenheit, so you won’t experience sudden cold or hot spikes.

Installation is made easier by its manageable size and compatibility with standard outdoor setups, including a remote control panel for indoor operation. The unit is built with durable materials like copper and stainless steel, ensuring it withstands outdoor conditions. It also includes safety features and has CSA certification, adding to its reliability. However, it requires careful winter preparations—users should drain the system if temperatures fall below 5°F to avoid freeze damage. It’s recommended for use below 2000 feet altitude, which might limit some high-elevation locations.

The product comes with a decent warranty (2 years on the whole unit and 5 years on the heat exchanger) and responsive customer support. While not the cheapest option, it strikes a good balance between performance, durability, and value for those needing dependable outdoor hot water without complicated installation.

The Rheem RTG-95XELN-3 is a solid choice if you need an outdoor tankless water heater that delivers continuous hot water for your whole house, with a strong flow rate of 9.5 gallons per minute. This means it can handle several fixtures at once, like showers and dishwashers, without running out of hot water. It is designed to be energy efficient, operating only when hot water is needed, which helps reduce energy bills. You’ll also appreciate the water-saving feature that can cut down water waste by up to 1,100 gallons a year.

Installation is easier than many older models thanks to its smaller size and lighter weight, and it has a weather-resistant design suited for outdoor mounting. The heater supports WiFi, allowing you to monitor and control it remotely, which is convenient. Rheem’s hot-start programming prevents cold water bursts, improving your comfort. Its maximum temperature is 140°F, which covers most household needs.

This model is non-condensing, so it might be a bit less efficient compared to condensing units, especially in colder climates. The energy efficiency rating of 0.82 is good but not top-tier. Also, it requires a 1/2 inch gas line and proper venting for safe outdoor use, so professional installation is recommended. This Rheem model fits well if you want an efficient, space-saving, and easy-to-manage outdoor water heater. It is particularly suitable for homeowners looking to save energy and water while ensuring plenty of hot water on demand.