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 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.

The Rinnai RE199eP is a well-built outdoor propane tankless water heater designed to supply continuous hot water for multiple fixtures, with a maximum flow rate of up to 9.8 gallons per minute. Its 199,000 BTU rating means it can handle strong temperature rises, making it suitable for homes in colder climates or those with higher hot water demands. The heater features a smart design that heats water only when needed, which helps save energy without sacrificing comfort. The LED display is a user-friendly touch, offering maintenance reminders and error codes to make troubleshooting easier.

Being an outdoor model, it’s built to withstand weather exposure, and Rinnai backs it with a solid warranty—15 years on the heat exchanger and additional coverage on parts and labor—giving you peace of mind about its durability. However, installation needs to be done by a professional, which could add to initial costs and complexity. Also, it’s a non-condensing model, meaning it may be less energy efficient compared to newer condensing units. If you want WiFi control, you’ll need to buy a separate module.

This water heater represents a strong choice for homeowners seeking reliable, high-capacity outdoor hot water with easy-to-use features, while considering the installation requirements and slightly lower energy efficiency compared to condensing options.