Rinnai RL75 
Tankless Water Heaters
Review and Buying Tips

Small, compact, and powerful, Rinnai RL75 tankless water heaters bring more for less.

Powered by natural gas or propane, RL75 models can be installed inside or outside a house, and with innovative technology, they ensure customer satisfaction and experience with no regret.

Rinnai RL75 tankless water heaters belong to the "Luxury" series, a series built to provide plenty of hot water to medium and large size homes.


Rinnai RL75 models review

Rinnai RL75

Rinnai tankless water heaters from the RL75 series, together with the RL94, are coming from the non-condensing and high-efficiency group that offers some features like the advanced models from RUC and RUR series. These heaters are recommended for families who need more than what the basic models from the V series offers.

Like the RL94 models, RL75 offers the Circ-Logic recirculation technology, for faster hot water delivery, isolation valves for safe installation and service, and a voice activation system, as an added convenience.

There are four models available from the RL75 group with an indoor and outdoor installation option and to use either natural gas or propane.

  • Rinnai RL75iN – an indoor model powered by natural gas
  • Rinnai RL75eN – an outdoor model powered by natural gas
  • Rinnai RL75iP – an indoor model powered by propane gas
  • Rinnai RL75eP – an outdoor model powered by propane gas

(available on Amazon.com)

Rinnai RL75i, as the indoor models, are designed with the sealed combustion and concentric vent-type system using the outside air for combustion safely to remove products of combustion to the outside atmosphere.

Designed as the direct-vent tankless water heaters, indoor models transfer products of combustion horizontally through the single wall and vertically with the roof penetration. They can be installed in any room type.

Rinnai RL75e models come with a ventless design so that they can be installed only outdoors and usually inside a recessed enclosure.

Feature review

Commercial grade components

Thanks to its commercial-grade components, Rinnai RL75 heaters can be used in residential and commercial applications, utilizing both LP and natural gas.

One of the essential elements in tankless water heaters is the heat exchanger, and those that are installed in Rinnai models have a great thermal transfer exposed to minimal thermal stress.


Both models from the RL75 series have the same maximum power of 180,000 BTU and hot water delivery of 7.5 GPM. These two features are what make models RL75i and RL75e recommended for homes with 2-3 bathrooms.

Like other models from Rinnai, the minimum water flow needed to activate RL75 units is low 0.4 GPM, making it great in situations where the low flow is required, such as shaving or hand/face washing and for low-flow fixtures.

On the other side, 7.5 gallons is the maximum capacity, but the EZConnect system allows the connection of two identical models into one system so they can provide more power and more hot water, making them ideal for tubs, spas, or bigger homes. For larger applications, there is an option to connect up to 25 tankless units by using the multi-unit control system.

Advanced electronics

Rinnai RL75 tankless water heaters utilize advanced electronics with the temperature controller on the front panel for extra convenience and diagnostics. Wi-Fi and Circ-Logic technology make remote monitoring, management, and recirculation control easy. Voice activation using Alexa ensures great convenience and user experience.

The outgoing hot water temperature is continuously monitored by the advanced electronic board, which adjusts the water flow to maintain the set temperature.

Small size

Rinnai water heaters RL75, with its attractive design, fits everywhere, inside or outside. No worries if it is installed inside as it features the sealed-combustion system with a zero clearance. The small size of 17.5" x 31" x 13" allows Rinnai tankless water heaters flexible, wall-mounted installation, and valuable space-saving.

Safety elements

  • Flame rod for the flame failure
  • Combustion fan rpm check
  • Boiling protection
  • Glass fuse for over current
  • Thermal fuse
  • Automatic frost protection
  • Remaining flame - OHS
  • Factory equipped with the condensate trap and drain line

Related: Higher-end model - Rinnai RUR98


  • Estimated yearly energy cost: $199 - natural gas; $482 – propane gas.
  • Energy factor is 0.82.
  • 12-year limited warranty on the heat exchanger and 5 years on other parts.
  • The MC-91-1US controller is supplied with the water heater - part of the front panel.
  • Meets California and Texas NOx emission requirements.
  • Direct electronic ignition.
  • Maximum working temperature is 140 F, the minimum is 98 F.
  • Gas and water fitting size is 3/4".
  • Water pressure range is from 20-150 PSI.
  • Isolation and pressure relief valves are included.
  • Certified for mobile and manufactured home installations.
  • Dimensions: 9.6" x 14" x 22.9".
  • Weight: 50 pounds.