10 Best Indoor Gas Tankless Water Heater 2026 in the United States

The Rinnai RXP199iN Condensing Smart Sense Tankless Water Heater is a solid choice for those looking for an efficient indoor gas water heater. With a flow rate of up to 11.1 gallons per minute (GPM), it can easily supply hot water to several fixtures simultaneously, making it ideal for larger households. Its high BTU rating of 199,000 means it can heat water quickly, ensuring you never run out of hot water when you need it most.

One of the standout features of this model is its impressive energy efficiency, with a UEF rating of .98. This means it can help you save on energy bills over time, which is a significant advantage for environmentally conscious consumers. The Smart-Circ technology is another highlight; it learns your hot water usage patterns to optimize recirculation, ensuring you get hot water faster without wasting energy.

There are some things to keep in mind. The installation process is recommended to be done by a professional, which could add to your overall costs if you're planning to buy this unit. Its compact size is a plus, but you'll still need adequate wall space for installation. Additionally, while it supports WiFi connectivity through the Control-R module, this feature is sold separately, which could be an extra expense for those looking for smart home integration.

The Rheem RTGH-95DVLN-3 is an impressive indoor gas tankless water heater that stands out for its high flow rate of up to 9.5 gallons per minute (GPM), making it suitable for larger households or homes with multiple hot water needs. Its energy efficiency rating of 0.93 indicates it uses fuel effectively, which could translate to savings on energy bills over time. The 199,900 BTU output ensures powerful performance, allowing for quick heating of water, which is beneficial for busy households.

A notable feature is its integrated digital display, which simplifies monitoring and adjusting temperature settings ranging from 100 to 140°F. This is particularly user-friendly for those who prefer precise control over their hot water. Installation is straightforward due to its compact size (17.7" W x 23.7" H) and wall-mountable design, fitting easily into various indoor spaces.

However, there are some considerations to keep in mind. While the warranties (1 year labor, 15 year heat exchanger, and 5 year parts) are decent, they may be shorter than what some competitors offer. The unit weighs nearly 60 pounds, which might require assistance during installation. Additionally, potential buyers should ensure their home can accommodate the venting requirements typical of gas water heaters, as this could complicate installation in some situations. The Rheem RTGH-95DVLN-3 is well-suited for families seeking an efficient and compact hot water solution, but prospective buyers should consider installation requirements and warranty coverage before making a decision.

The Rheem RTGH-95DVELN-3 is a strong choice for an indoor gas tankless water heater, especially if you want reliable hot water for multiple uses at the same time, like showers and dishwashers. It delivers a high flow rate of 9.5 gallons per minute, which means it can comfortably serve a whole household. Its energy factor of 0.93 indicates that it is very efficient, helping to reduce energy bills by only heating water when needed. The unit uses condensing technology, which typically requires specialized venting to safely expel exhaust gases, so proper installation space and vent setup are important to consider.

The dimensions (about 18 by 24 inches) make it compact enough for most indoor installations, saving space compared to traditional tank water heaters. A standout feature is the built-in Wi-Fi EcoNet system, allowing you to monitor and control the water heater remotely, track energy usage, and get alerts for maintenance, which adds convenience and helps prevent unexpected issues. Additionally, the LeakGuard system provides extra protection against leaks, potentially saving you from water damage.

While the 9.5 GPM flow rate suits average to larger families, it might be more than needed for smaller households, and installation requires professional handling because of venting and gas connections. Rheem typically offers solid warranty coverage on their units, which can provide peace of mind. This water heater is well-suited for users looking for efficiency, smart control, and a reliable hot water supply in a compact indoor unit, though installation complexity and venting requirements are factors to plan for.