10 Best Outdoor Tankless Water Heaters 2025 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 Rinnai RX199iN Condensing Smart Sense Tankless Water Heater is a solid choice for those seeking an efficient and high-capacity hot water solution for their home. With a flow rate of up to 11.1 gallons per minute (GPM), this heater can handle multiple fixtures simultaneously, making it ideal for larger households or homes with high hot water demand. Its 199,000 BTU rating ensures that it heats water quickly, maintaining a steady supply.

Energy efficiency is a standout feature, boasting a UEF rating of .98, which means it can help lower energy bills compared to less efficient models. The compact design allows for versatile installation, either indoors or outdoors, with the necessary Versa Vent system. This flexibility is a significant advantage for users with limited space.

However, installation isn't a DIY project; it requires professional help, which could add to the overall cost. Additionally, while it has a robust warranty and support system, some users may find the initial purchase price higher than standard water heaters.

The Rinnai RE199eN is a non-condensing natural gas tankless water heater designed for outdoor installation, capable of delivering up to 7.6 GPM, making it suitable for homes with multiple fixtures running simultaneously. Its compact size, comparable to a small suitcase, allows for a space-saving installation. With a powerful 199,000 BTU rating, it ensures a significant temperature rise and reliable hot water supply.

The energy-efficient design heats water only when necessary, helping conserve energy and potentially lowering utility bills. The LED display is a useful feature, providing service reminders and error codes for easy maintenance and troubleshooting. Durability is a key strength of this model, with residential guarantees covering the heat exchanger for 15 years, labor for 5 years, and parts for 1 year. Additionally, it’s built to withstand outdoor conditions, making it a robust choice for external setups.

However, professional installation is recommended, which could add to the initial cost if you don't have the skills or tools to install it yourself. Also, the WiFi control module is sold separately, which might be a downside for those looking for integrated smart home features out of the box. This Rinnai unit is a strong contender for users needing a reliable, energy-efficient, and durable outdoor tankless water heater, provided they are willing to invest in professional installation and potentially additional accessories.