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 RX160iN is a versatile tankless water heater designed for both indoor and outdoor use, making it a flexible choice if you want installation options. It delivers up to 9 gallons per minute, enough to supply six fixtures at once, which should cover most household needs comfortably. Its high BTU rating of 160,000 means it can provide a strong temperature rise, keeping your water hot even in colder climates. The unit boasts an impressive energy efficiency rating (UEF 0.97), which helps save on energy bills over time. Installation requires a professional, especially for outdoor setups where the Versa Vent system and an outdoor vent cap are necessary for safe operation.

The product is built with durability in mind, suitable for outdoor weather conditions when installed properly. A helpful Quick Flush feature makes maintenance easier, potentially extending the unit's life. While the heater offers smart controls and optional WiFi connectivity for convenience, those features require additional purchase. The warranty and support from Rinnai are reliable, adding peace of mind.

At 54 pounds, it’s relatively heavy, and installation can be complex and costly if you don’t have a professional. Also, while the flow rate is good for most homes, very large households with high simultaneous water use might need a larger system. This model serves as a strong, efficient choice for those wanting a flexible, high-performance tankless water heater suitable for both indoor and outdoor installation.