Rinnai RC80 Tankless Water Heaters Review

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Rinnai RC80 condensing water heaters review. Explore features, benefits, and specs of Rinnai tankless water heaters; indoor RC80i and outdoor RC80e model. The review shows its smart and powerful features, advanced technology that provides efficient and powerful heating, yet flexible, safe and reliable for you and your family.

Rinnai RC80 tankless water heaters are coming from the "Ultra Line" series, a series that is consisted of four models that are using condensing and tankless technology. Condensing technology brings the higher efficiency and superior water heating to your home, while tankless technology provides space savings, endless hot water, heating on demand and other great benefits.


Rinnai RC80 series overview

rinnai ru80iWith the energy efficiency of over 0.82 Rinnai condensing water heaters from RC80 series are Energy Star qualified and therefore eligible for additional rebates.

Rinnai RC80 models are smaller than other condensing RC98 units; its maximum gas input is 157,000 BTU, and the water flow is lower; 8 gallons per minute.

This is why they are recommended for mid to large-sized homes and up to three applications. The temperature of the outgoing hot water is monitored all the time and in order to maintain the set temperature Rinnai adjusts the water flow.

RC80i vs. RC80e

rinnai ru80eThere are two RC80 models; an indoor RC80i and RC80e for an outdoor installation; both utilizing natural gas and propane.

These are designed for both residential and commercial applications.

Rinnai RC80i is designed as the direct vent unit, with the zero tolerance to the combustibles, and with the flexible vent system, it is ideal for almost any room in your house.

These indoor models are using Rinnai exclusive venting system, with the concentric design; pipe inside the pipe, where the outer pipe is used to get the fresh air from the outside while the inner pipe for expelling gases out.

The RC80 indoor model can use horizontal or vertical venting, which depends on your preference and installation viability.

Rinnai RC80e is an outdoor tankless water heater that is usually installed in the protective recess box outside of the house and is not using the vent pipes for flue gases.


Capacity and power

RC80 water heaters can operate between its minimum 9,500 and maximum heating power of 157,000 BTU as they utilize a modulating gas valve which also reduces the temperature fluctuation as the power is adjusted based on the water flow. The minimum amount of hot water these units can deliver is 0.4 GPM, ideal in the situation where a trickle of water is needed, while the maximum 8,0 gallons per minute can supply even larger homes.

Two heat exchangers

Rinnai water heaters from RC80 series are equipped with two commercially grade heat exchangers. One heat exchanger is made of the stainless steel and it uses the residual heat from the flue gases while other is copper-made and it uses pre-heated water. The condensing technology allows these Rinnai tankless water heaters high-efficiency of close to 97% for both natural and propane gas.

Automatic temp. adjustment

RC80 heaters are able to control the temperature of the outgoing hot water and can adjust the water flow to adjust the temperature setting.

Safety elements

  • Flame rod for the flame failure; the unit will shut down when the burner flame is extinguished

  • Combustion fan rpm check

  • Boiling protection

  • Glass fuse for over current

  • Thermal fuse

  • Frost protection

  • Remaining flame - OHS

  • Factory equipped with the condensate trap and drain line


  • 12-year limited warranty on the heat exchanger

  • MC-91-1US controller is built-in the water heater. It can set the temperature within a specific range and provide error codes for easy troubleshooting.

  • Compatible with Rinnai digital controllers

  • Meets California and Texas NOx emission requirements

  • It is not using the pilot light, but direct electronic ignition

  • The temperature is factory set at 120 F, while the maximum working temperature is 140 F and the minimum is 98 F

  • Gas and water fitting size is 3/4"

  • Water pressure range is from 15-150 PSI

  • Isolator and pressure relief valves are included

  • Pair up with the hydronic furnace for efficient home heating

  • Dimensions: 18.5x10.7 (10.5)x26.4"

  • Weight: 64 (71) pounds

Rinnai RC80 condensing and tankless water heaters provide continuous water supply, on demand and in an endless flow, for residential and commercial applications. They can also be combined with the hydronic furnaces for home heating and providing hot water, at the same time.

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Pictures - courtesy of Rinnai WH company

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