10 Best Tankless Hot Water Heaters 2025 in the United States

The Rinnai RXP199iN is a versatile tankless water heater designed for both indoor and outdoor use, thanks to its Versa Vent system. It runs on either natural gas or propane, which adds flexibility depending on your fuel preference. With a strong flow rate of up to 11.1 gallons per minute, it can supply hot water to around seven fixtures simultaneously, making it suitable for medium to large households. Its energy efficiency is excellent, boasting a UEF (Uniform Energy Factor) of 0.98, which means it uses fuel very efficiently and can help reduce energy bills.

The built-in Smart-Circ recirculation pump is a smart feature that learns your hot water usage patterns and adjusts accordingly, improving efficiency and convenience by reducing wait times for hot water. The water heater is quite compact, about the size of a small suitcase, which helps save space during installation. However, it is fairly heavy at 58 pounds and requires professional installation, which could add to upfront costs. The maximum temperature is 140°F, which fits most household needs. While it offers WiFi connectivity through an optional Control-R module for remote monitoring and control, this is not included and must be purchased separately.

Customer reviews are positive, with a high rating around 4.6 out of 5, reflecting satisfaction with performance and reliability. This Rinnai model is a solid choice for those needing reliable, efficient, and flexible hot water delivery, especially if you want advanced features like smart recirculation and WiFi control. Be prepared for professional installation and consider the additional cost of the WiFi module if desired.

The Rinnai RL75IN Tankless Hot Water Heater offers a robust performance with a flow rate of 7.5 gallons per minute (GPM), making it capable of supplying hot water to up to 5 fixtures simultaneously. This is particularly advantageous for families or homes with multiple bathrooms. The unit uses natural gas, which can be more cost-effective compared to electric models, and it is designed for indoor installation, saving outdoor space and making it suitable for various home layouts.

The compact size is another plus, as it can fit into smaller spaces without sacrificing performance. A notable feature is its Circ-Logic technology, which allows users to set recirculation patterns based on their hot water usage habits, potentially leading to reduced water and energy wastage. However, the unit is non-condensing, meaning it may not be as energy-efficient as condensing models, which could lead to higher operational costs over time.

The product includes a solid warranty, with up to 12 years on the heat exchanger for residential use, but it is recommended to have it professionally installed, which could add to the initial cost. Additionally, while it offers WiFi control, the necessary module is not included and must be purchased separately. This heater is best suited for mid to large-sized homes that require reliable and continuous hot water supply, but it may not be the best choice for those looking for the highest energy efficiency or those on a tight budget due to the additional installation and WiFi module costs.

The Rinnai RE180eP is a propane-powered outdoor tankless water heater designed to deliver hot water on demand without storing it. It offers a strong maximum flow rate of up to 8.5 gallons per minute, which is suitable for running multiple fixtures like showers and faucets at the same time in medium to larger households. Being non-condensing, it’s simpler in design but slightly less energy-efficient compared to condensing models, though it still includes features like an LED display to help with maintenance and efficiency reminders.

This model’s compact size, roughly like a small suitcase, makes it easier to install in limited outdoor spaces, but professional installation is recommended to ensure safety and proper setup. It provides a solid temperature rise capacity to meet typical household needs, though exact temperature increase depends on your incoming water temperature and region. The heater comes with a layered warranty—15 years on the heat exchanger, 5 years on labor, and 1 year on parts—to support long-term reliability.

A convenient option is the ability to add WiFi control via an additional module, allowing remote monitoring. This Rinnai unit is a strong choice for those wanting a reliable, high-flow propane outdoor tankless heater with smart features and solid support, while noting it may not be the highest in energy efficiency compared to condensing models.