10 Best Tankless Hot Water Heaters 2026 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 Rheem RTEX-24 Electric Tankless Water Heater is a solid choice for those seeking an efficient and high-capacity water heating solution. One of its major strengths is its impressive flow rate of up to 5.9 gallons per minute (GPM), which is suitable for serving multiple fixtures simultaneously. Additionally, its 99.8% energy efficiency rating makes it an economical option, as it minimizes energy waste and reduces utility bills.

The electric fuel type ensures ease of installation without the need for gas lines, making it a convenient option for many users. Its compact size (17.63"W x 18.25"H x 3.5"D) and wall-mount capability further enhance its suitability for smaller spaces or areas where floor space is at a premium. The product also boasts a user-friendly digital temperature display and self-modulating power control, which contribute to maintaining consistent and continuous hot water supply on demand.

However, there are some drawbacks to consider. The maximum flow rate may not be sufficient for larger households with high hot water demands during peak usage times. In summary, the Rheem RTEX-24 is an excellent option for small to medium-sized households or professional use, offering high efficiency, ease of installation, and reliable performance within its capacity limits.

The Rheem Natural Gas Condensing Tankless Water Heater offers a strong flow rate of up to 9 gallons per minute, suitable for households needing multiple hot water sources at once, such as showers and appliances running simultaneously. It operates on natural gas, which is often more cost-effective for home heating than electricity, and boasts a good energy efficiency rating of 0.93, helping reduce energy bills while providing continuous hot water. Its temperature settings range from 100 to 140°F, with a default of 120°F, allowing comfortable control over water temperature. The unit is compact, measuring about 18 by 24 inches, making it a good fit for indoor wall mounting without taking up much space. Installation requires venting due to the direct vent feature.

Rheem backs this model with a solid warranty: 15 years on the heat exchanger, 5 years on parts, and 1 year labor, which gives reasonable peace of mind regarding reliability and service. Some users appreciate features like hot start programming that reduces delays in hot water delivery, and the LED display for easy monitoring. On the downside, the 1-year labor warranty may be short compared to some competitors, and the unit's weight (about 60 pounds) means installation might require professional help. The maximum temperature cap at 140°F is standard but may be limiting for those needing hotter water for specific uses.

This heater is well-suited for medium to large households looking for efficient, continuous hot water with natural gas fuel and a compact indoor design.