This article on Rheem Tankless Water Heater Temperature Adjustment will describe:
- How to adjust Rheem Tankless Water Heater?
- What temperature should a Rheem Tankless Water Heater be set at?
- FAQs
- End-Note
Rheem Tankless Water Heater Temperature Adjustment
Let’s learn how to adjust the temperature on a Rheem Tankless Water Heater, whether it’s powered by gas or electric.
How To Adjust Temperature On Rheem Electric Tankless Water Heater:
- Click the adjustment knob to turn on the display.
- Turn the adjustment knob clockwise to increase the water temperature.
- To decrease the water temperature, turn the adjustment knob counterclockwise.
How To Adjust Temperature On Rheem Gas Tankless Water Heater:
The default temperature of a tankless water heater is 120 degrees. According to the Consumer Product Safety Commission, you should set the temperature to 120°F to prevent burns in small children and elderly people.
However, if you want to set the temperature above the default setting (120°F), follow these steps below:
- Turn on the remote control by pressing the power button.
- Turn off the gas and water supply to the unit by closing the shut-off valves.
- Press and hold down the Up adjustment button until 120°F shows in the LED display.
- While 120 is shown on the display, hold down the Up button for 5 seconds until the 140 is flashing. Now, press the down button to set the temperature to 140. Then, press the up or the down button to set the temperature to 125, 130, 135, or whatever preference you want.
To disable the ability to set above 120°F, refer to the following steps:
- Press and hold the Down button until 100 appears on the LED display.
- Press and hold the Down button for 2 seconds. While holding the down button, tap the Up button. Then, release both buttons.
What Temperature Should A Rheem Tankless Water Heater Be Set At?
You should set the temperature to 120°F on the Rheem Tankless Water Heater. It’s because both the manufacturer and the CPSC recommend this temperature setting to prevent burns.
Safety and energy conservation are the criteria you must consider when selecting the temperature setting.
Setting the temperature above 125°F will result in death or severe burns from scalding. You can check the Time/Temperature Relationships in Scalds table to know why safety matters when selecting a temperature setting:
| Water Temperature | Time To Produce A Serious Burn |
| 120°F | More than 5 minutes |
| 125°F | 1 1/2 – 2 minutes |
| 130°F | About 30 seconds |
| 135°F | About 10 seconds |
| 140°F | Less than 5 seconds |
| 145°F | Less than 3 seconds |
| 150°F | 1 1/2 – 2 seconds |
| 155°F | About 1 second |
Similarly, raising the temperature to a higher setting can increase energy consumption. A 10°F reduction in temperature will save you about 3-5% energy.
In short, we recommend you set the tankless water heater temperature to 120°F if you have children or senior citizens in your home. Otherwise, you can turn the temperature above 125°F or 140°F for higher water demands.
FAQs
What is the best setting for a Rheem water heater?
120-degree F is the best temperature setting for your Rheem Water Heater- it doesn’t matter if it’s a tank or tankless unit. The Consumer Product Safety Commission also recommends this setting to prevent burns in children and senior citizens.
What is the ABC temperature setting on a Rheem water heater?
On a Rheem Water Heater, A means 120°F, B means 130°F, and C means 140°F. I recommend you set the temperature to 120°F against burns.
Is 140 too hot for a tankless water heater?
Yes, 140 is too hot for a tankless water heater. A child can burn within a couple of seconds by 140°F water.
End-Note
Adjusting the temperature on a Rheem Tankless Water Heater is simple.
On an electric tankless water heater, play with the adjustment knob on the unit to increase or decrease the temperature by turning the knob clockwise or counterclockwise.
On the other hand, you should press the Up or Down buttons on the remote control to increase or decrease the temperature on a gas tankless water heater.
I highly recommend you set the temperature to 120 degrees to get sufficient hot water while ensuring the safety of children and older people.
However, you can turn the temperature above 125 or 140 degrees for higher water demands.
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Sohel Rana is an expert writer (Of course, the owner and founder of this blog) on plumbing, HVAC, and appliance repair & troubleshooting. Since 2020, he has written on these specific topics, though his writing journey began in 2018.
