How To Adjust Temperature On Rinnai Tankless Water Heaters (5 Steps)

Do you want to learn how to adjust the temperature for your Rinnai tankless water heater?

The main first step is to remove the front panel to expose the 'guts' of your Rinnai tankless water heater.

In this guide, I will go over...

  • Removing the front panel
  • Pressing the priority button
  • Changing switch #6 in dip switch SW1
  • Changing switch #5 in dip switch SW1

Let's get started with this guide!

how to adjust temperature on rinnai tankless water heater (1)

Adjusting Max Temperature On Rinnai Tankless Water Heaters

Nothing is more annoying that going through the hassle of installing a tankless water heater only to realize it doesn't get hot enough for your household.

Unfortunately, some homeowners never realize that the default 120F on Rinnai heaters can be increased. There are a few simple steps to increase this default temperature, and most Rinnai tankless water heaters can be increased to a high of 140F.

The first main step of adjusting the Rinnai temperature is to remove the front panel of the heater.  And most Rinnai tankless heaters can be adjusted by flipping a dip switch. Dip switches are small switches in series on the circuit board. Other Rinnai units may have a specific button procedure instead rather than a dip switch.

In this guide, the instructions will be specifically based on the Rinnai V53DE tankless water heater, but the general procedure will be similar to other units. To find the exact settings for your Rinnai heater, I recommend that you read the installation manual.

Read Also: What Are The Best Rated Tankless Water Heaters For Cold Climates?

Step 1 - Turn Power On

In order to adjust the default temperature on a Rinnai unit, the power has to be on.

You will be modify a dip switch but you will be also be pressing buttons on the unit, so the power has to be active.

Step 2 - Remove Front Panel

The first step to change the default max temperature on a Rinnai tankless heater is to remove the front panel.

There are two plastic trim sections on each side of the water heater that you can slide out. Once the trim pieces are removed, the screw heads are exposed. You can remove the four screws with a screwdriver or electric drill.

Carefully remove the front panel.

Read Also: What Are The Best Outdoor Tankless Water Heaters?

Step 3 - Press Priority Button

The priority button needs to be green and glowing.

If not, press the priority button.

Step 4 - Flip Switch #6 in Dip Switch SW1

Take a look at the dip switches inside the Rinnai tankless heater, these are the tiny switches in series connected to a circuit board.

With A Temperature Controller

If your Rinnai tankless heater has a temperature controller (up/down arrows to change the temperature), then there is a particular switch to flip.

To adjust the max temp to 140F (rather than 120F), you will have to flip switch #6 in the dip switch SW1. 

Dip switch SW1 is the row of tan-colored switches inside the heater. You must flip the switch #6.

Without A Temperature Controller

If your Rinnai tankless heater doesn't have a temperature controller, then there will only be two temperature settings—the default 120F and the max 140F.

To change the temperature setting to 140F, you will have to flip switch #5 (rather than #6) in the SW1 dip switch (tan-colored switches).

Read Also: What Are The Top Point-Of-Use Tankless Water Heaters?

how to adjust temperature on rinnai tankless water heater

Step 5 - Verify Temperature Change

If you have a temperature controller, you simply hit the up arrow to see if you can get to a higher temperature, and to verify that the dip switch worked.

If you don't have a temperature controller, you can open up a faucet and see if you get a higher temperature.

Step 6 - Install Front Panel

After you have changed the default temperature setting, and verified the change, you can now re-install the front panel.

Simply put back in the four screws, and slide the two plastic trim pieces onto the side.

Read Also: What Are The Best Rated Tankless Water Heaters For Cold Climates?

Safety Issues With Raising Max Temperature

Always be careful when adjusting hot water temperatures in a household, especially if you have small children. Scalding can occur in just three seconds at a water temperature of 140F.

If your Rinnai tankless water heater doesn't have a temperature controller, and you have small children, the CDC recommends keeping it at the default 120 degrees Fahrenheit or lower.

If you have a temperature controller, you can adjust it anywhere from 120F and up but below the maximum temp of 140F after raising the default.

Not Enough Hot Water

And after raising the default, if you aren't getting enough hot water, you may want to lower the temperature a bit.

If you lower the temperature to what you actually use at the faucet, then you won't need to mix in as much cold water at the faucet, and you will get more hot water.

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Arie Van Tuijl

Arie Van Tuijl

I am a licensed home inspector in two U.S. states and the founder of Home Inspector Secrets. After performing hundreds of inspections, and seeing thousands of house defects, I realized people would love to have an online resource dedicated to home maintenance. I write detailed home guides and product reviews sprinkled with inspection tips. You can read my bio here.

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Home Inspector Secrets is an online resource for owners, buyers, and sellers to understand all aspects of home maintenance. We have detailed home guides, product reviews, inspection advice, and much more.