10 Best Tankless Hot Water Heaters 2025 in the United States

The Rinnai RX199iN is a powerful tankless water heater that stands out for its impressive flow rate of up to 11.1 gallons per minute, making it suitable for homes with multiple fixtures needing hot water simultaneously. It's designed to operate on either natural gas or propane, giving you flexibility depending on your fuel source. The energy efficiency is top-notch, boasting a UEF rating of .98, which means it uses energy very effectively, potentially saving you on utility bills.

One of the great features is its compact size, comparable to that of a small suitcase, making it easier to fit into various spaces. The Smart Sense gas control system adds convenience, allowing for easier operation. However, the installation of this unit is recommended to be done by a professional. While this ensures safety and proper functionality, it could increase your expenses if you don’t have a technician readily available.

While its high efficiency is a significant advantage, it may not be the best choice for all water temperature needs depending on your region’s groundwater temperature. Additional considerations include the need for the RX-OVC vent cap for outdoor installation, which adds to the installation complexity and cost. Also, the Controlr module for WiFi control is sold separately, which might be a drawback for those looking for smart home integration right out of the box. If you are looking for a tankless heater that offers high performance and efficiency, the Rinnai RX199iN is a strong contender. Just ensure you’re prepared to handle the installation requirements and additional features you may want to consider.

The Rinnai V75IN is a natural gas tankless water heater designed for indoor use, delivering a flow rate of up to 7.5 gallons per minute (GPM). This means it can efficiently provide hot water to around five appliances at the same time, making it suitable for medium-sized homes or households with moderate hot water demand. Its compact size (30" wide by 13" high) helps save space compared to traditional tank heaters.

In terms of energy efficiency, it has a solid Energy Factor of 0.82, which means it uses gas efficiently by heating water only when you need it, reducing waste and utility costs. The unit also features leak detection to prevent water damage and a temperature range adjustable between 98ºF and 140ºF, offering good control to match your comfort preferences. Installation is intended to be professional, which is important as improper setup can affect performance and safety. The heater runs on natural gas, a common and generally cost-effective fuel choice. Warranty protection includes 10 years on the heat exchanger, 5 years on labor, and 1 year on parts, which provides confidence in the product's durability and support.

Some potential drawbacks include the 7.5 GPM flow rate which might be limiting for larger households with high simultaneous hot water needs. Additionally, the requirement for professional installation adds to initial costs and complexity. The temperature range may not suit users wanting water temperatures above 140ºF, though this limitation is typical for safety reasons. The Rinnai V75IN delivers reliable, energy-efficient hot water with a good flow rate for most average homes, especially those preferring natural gas and seeking space savings. Consider its flow capacity and installation requirements to determine if it meets your household needs.

The EcoSmart ECO 11 electric tankless water heater is a compact and energy-efficient choice ideal for small spaces like bathrooms, office breakrooms, or point-of-use applications. It delivers continuous hot water on demand without the need for a storage tank, which helps save energy since it only heats water when needed. With a maximum flow rate of about 3.1 gallons per minute, it works well for low-demand situations, but it might struggle if you need to run multiple showers or faucets at the same time.

Operating at 240 volts with a 13kW power rating, it offers a reliable temperature rise, maintaining water temperature within 1 degree of your setting thanks to its self-modulating technology. Installation is straightforward since it’s wall-mounted and quite small compared to traditional heaters, saving valuable space in your home. The heater also features an easy-to-read LED display for monitoring settings. One thing to keep in mind is the relatively high amperage draw (54 A), so your electrical setup needs to support that.

The lifetime warranty on electronics and heating elements is a nice reassurance, although it doesn’t cover installation costs or incidental damages. If you need a compact, efficient, and simple tankless water heater for light use or a single bathroom, this model makes a solid choice. For larger households or heavy hot water users, a unit with a higher flow rate would be more suitable.