How a Rinnai Tankless Water Heater Works




The physics and mechanics of turning cold water into hot showers 


Step by step:

  • When hot water is needed, turning on a shower, washing machine, dishwasher, or faucet, cold water flows through the Rinnai Tankless Water Heater from the inlet pipe to the bottom of the heater.
  • The flame ignites and heats two heat exchangers included in the Super-High- Efficiency models.
  • Preheated water passes through a stainless steel heat exchanger capturing any extra or latent heat before it escapes through the vent system.
  • Water continues to be heated as it passes through the copper heat exchanger and exits from the water heater outlet pipe to travel through the pipes through the home, wherever hot water is needed.
  • The tankless water heaters adjust the flame output to insure the temperature set point is maintained.
  • When the hot water fixtures shuts off, cold-water stops flowing through the tankless system and the flame diminishes.

Your water heater is now off until the next time you want hot water. No more heating unused water.

—This video is provided by Rinnai, one of ProTradeCraft's advertisers. Rinnai is one of the world’s largest gas appliance manufacturers, specializing in high-efficiency residential and commercial tankless water heaters and home heating solutions. View all of Rinnai's content.




Are there models available that can be used to supply HW to a dishwasher, kitchen sink, washer, lavatory and shower. Obviously all of them will not be in use at the same time. However there could be a combination of any two at one time.


Hi Mike,

Rinnai has a comprehensive portfolio of tankless water heaters that provide whole home water heating solutions, so your family can enjoy an endless supply of hot water, anywhere in your home, with multiple hot water needs being fulfilled at the same time.   

With so many different options Rinnai has a Residential Product Finder so you can be sure to select the right tankless water heater for your home and your needs. Please let us know if you have any other questions.

Thank you.

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