Rinnai tank less water heaters are not like tank models where the user mixes hot & cold water to get a comfortable temperature.  The Rinnai sets the water temperature at the unit or with the use of an accessory temperature controller.  When a user steps into the shower they turn on the hot side only – no cold.


     If the temperature at the unit is set to 120, and the user blends the hot & cold water, the amount of water flowing through the Rinnai is reduced and safety mechanisms shut off the unit to prevent it from over heating.


     Flow restrictors in a faucet can reduce water flow enough to shut off a Rinnai if the temperature is set too high.


The Answer is: Turn the temperature at the unit (or on the controller) to a lower setting.  My Rinnai is set to 98 in the summer and 104 during the winter months.  When I actually need hot water, I go to the temperature controller (I have one at either end of the house for convenience) and adjust the temperature.  Every house and water service is different.  Try setting your Rinnai at 108.  If you add cold water at the shower then turn it down, if you want it hotter, turn it up.


     Just because you can turn it up doesn't mean you have to turn it up.  If you find that you have to set your Rinnai above 110 to get a hot shower then there may be another problem – call your plumber.  Maybe the pipes aren’t insulated or maybe there is a crossover of hot & cold water somewhere causing a problem.


     Rinnai tank less water heaters are terrific units and very efficient, when used correctly, they will last a long, long time.  There is a unit at my other house that is better than 17 years old.


     If you would like more information on Rinnai tank less water heaters, call (757) 596-7400 and leave a message or send an e-mail to 64west@gmail.com.

my rinnai shuts off while i'm using it

Rinnai Temperature Controller.jpg