10 Best Outdoor Tankless Water Heaters 2025 in the United States

The Ranein Natural Gas Tankless Water Heater is designed for outdoor use, providing a maximum flow rate of 5.3 gallons per minute (GPM) and a high heating capacity of 130,000 BTU. This unit promises instant hot water, eliminating the traditional wait time associated with tank water heaters. The fan placed underneath ensures safe operation and full combustion, with low noise and enhanced durability. It supports multiple outlet points, making it suitable for a whole household.

Installation is simplified with standard fittings and compact dimensions, though it requires a 120-volt power source for operation. Its anti-freeze protection is an advantage for colder climates, though it is not recommended for areas over 2,000 feet of elevation. The water heater is durable and weather-resistant, but potential users should ensure the pressure relief valve is opened to drain water when not in use during cold weather to prevent internal damage.

The product comes with helpful customer support. Those looking for a reliable, high-capacity tankless water heater for outdoor use and can handle the installation requirements and maintenance precautions should find this model very beneficial.

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 Ranein Propane Gas Tankless Water Heater offers a robust heating capacity of 100,000 BTU and an impressive hot water flow rate of 4.3 gallons per minute (GPM). It's designed to deliver continuous hot water to multiple points in a household such as bathrooms, kitchens, and bars, making it a good option for medium-sized homes. One standout feature is the 'Four Seasons Function,' which automatically adjusts water temperature based on seasonal changes, ensuring consistent comfort throughout the year. The 'No Waiting Required' feature means you get instant hot water without the preheating delay typical of traditional tank water heaters, adding to its convenience and efficiency.

The included vent pipe helps reduce additional costs, and the oxygen-free copper water tank improves energy efficiency by minimizing heat loss. This heater is also easy to install with standard 1/2" NPT water fittings and gas inlet. However, it is not recommended for areas above 2,000 feet elevation, which limits its usability in high-altitude locations. Additionally, the recommendation for professional installation could add to the setup costs. With a 4.3-star rating from 348 customer reviews, the product is generally well-received, but prospective buyers should be aware of these limitations.

Its compact size (18.89"W x 8.85"H) and manageable weight (28 pounds) make it relatively easy to handle. It is a solid choice for those seeking a reliable and efficient tankless water heater, provided it fits within the geographical and installation requirements.