How to Turn Up a Hot Water Heater

Co-authored by Dave Jones

Last Updated: November 26, 2022 References

Cold water can be an inconvenience while bathing, washing dishes, or doing chores around your house. If you consistently notice cooler water temperatures, you may need to turn up your water heater's temperature. While adjusting a gas or electric water heater requires careful hands and an understanding of the parts, it can be a simple fix. As long as you take precautions while handling your water heater, you should be able to adjust the temperature quickly.

Method 1

Method 1 of 3:

Adjusting a Gas Water Heater

1
Put out any other open flames before adjusting the gas water heater. Natural gas is flammable and, while you should not come in direct contact with the gas, safe is better than sorry. Avoid using candles, cigarettes, or other open flames in the home while you're adjusting the water heater.
- You do not need to turn off the gas while adjusting the water temperature.
2
Locate the dial on the front of the water heater. This is the gas control valve. It is usually a black or red knob with 2 sides: warm and hot. In some cases, it might also have notches on the side to clearly mark these temperature options.^{[1]
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Expert Source

Dave Jones
Master Plumber, Roto-Rooter Plumbing & Water Cleanup
Expert Interview. 29 March 2021.}

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3
Twist the dial from the warm to the hot side. Do not turn the dial completely to hot. First, move it slightly towards hot from where it was before. If the temperature is moved completely to hot, the water may scald your hand. You can always move it further towards hot later on, if needed.^{[3]
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4
Wait 3 hours, then check the water temperature. Wait at least 3 hours before you check the water temperature again so it has time to heat. If the water temperature is still too low, or it feels too cool, adjust the gas control valve again.^{[4]
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- Avoid raising the temperature above 120 °F (49 °C) to prevent serious burns.^{[5]
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  Expert Source
  
  Dave Jones
  Master Plumber, Roto-Rooter Plumbing & Water Cleanup
  Expert Interview. 29 March 2021.}

Method 2

Method 2 of 3:

Turning Up an Electric Water Heater

1
Turn off the water heater circuit breakers. Locate your home's circuit board at the electrical box. Because most water heaters use about 240 Volts of electricity, you should need to switch off 2 breakers. Consult the location sheet on the inside of the panel for details—if they are unlisted, turn off all of the panels to be safe.^{[6]
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Expert Source

Dave Jones
Master Plumber, Roto-Rooter Plumbing & Water Cleanup
Expert Interview. 29 March 2021.}
- Never adjust the electric water heater without turning off the circuit breakers. To prevent electrocution, contact an electrician if you're not sure how to turn off the breakers.
2
Remove the heater's access panels. The access panel(s) should look like rectangular boxes on the front of the water heater. Water panels have either single or double access panels, so pry open 1 or both to reach the panel's inner controls.^{[7]
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- Most panels do not need a screwdriver to be opened. Your hands should be enough.
3
Remove the insulation to find the thermostat. You should notice a thin padding of insulation between the thermostat and the access panels. Take out all of the insulation to get a clearer look at the thermostat and raise the temperature as needed.^{[8]
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- Store the insulation somewhere safe—it will need to go back in the water heater to keep the thermostat temperature accurate.
4
Adjust the thermostat to a higher temperature. Most thermostats are turned via a screw in the middle. Place a flat tip screwdriver into the screw and turn it several notches higher. Raise the thermostat temperature no higher than 120 °F (49 °C) to prevent burns.
- The thermostat should show temperatures from about 90 °F (32 °C) to 150 °F (66 °C), though 120 °F (49 °C) is the recommended maximum.^{[9]
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  Expert Source
  
  Dave Jones
  Master Plumber, Roto-Rooter Plumbing & Water Cleanup
  Expert Interview. 29 March 2021.}
- Even if there are 2 panels, there should only be 1 thermostat. The number of panels more has to do with the water heater's design, as both panels should open up to the same thermostat.
5
Close up the panels and wait to test the water. Put the insulation back into the heater and close 1 or both panels. When you're ready to check the water temperature, turn the power back on. Wait at least 3 hours before checking the water and evaluate: if it still reads or feels too low, adjust the temperature again.^{[10]
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Method 3

Method 3 of 3:

Checking Your Water Temperature

1
Run the hot water for 3-5 minutes. Choose the sink nearest to your hot water heater and let it run for at least 3 minutes. For the first few minutes, any water running out of the sink will have already been in the pipes. It needs to clear out before you test the water heater so you can get an accurate reading.^{[11]
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2
Use a candy or cooking thermometer to test the water temperature. Put the water in a bowl or cup and take its temperature immediately. Leave the thermometer in the water for at least 20-30 seconds to get a trustworthy reading.^{[12]
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3
Record the temperature number. While cold water is a problem, you also don't want your water temperature to be too hot. If it reaches anywhere above 120 °F (49 °C), you run the risk of sustaining burns. Consult the following numbers to see the relationship between temperature and how long it will take to produce serious burns:^{[13]
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- 120 °F (49 °C): 5+ minutes
- 125–130 °F (52–54 °C): 60-120 seconds
- 130–140 °F (54–60 °C): 5-30 seconds
- 140–150 °F (60–66 °C): 1-5 seconds
- 150–160 °F (66–71 °C): 1-1 1/2 seconds
- 160 °F (71 °C) or above: Immediately
4
Check again in about 3 hours, if needed. If the reading is too low or too high, re-adjust the water heater as needed and check the temperature again in 3 hours. The water heater will need time to change its internal temperature and warm or cool the water to the correct temperature.^{[14]
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Expert Q&A

Question

How high can you turn up a hot water heater?

Dave Jones
Master Plumber, Roto-Rooter Plumbing & Water Cleanup
Dave Jones is a Professional Plumber and the Midwest Regional Vice President at Roto-Rooter Plumbing & Water Cleanup. In 1992, Jones joined Roto-Rooter as a drain service technician at the age of 18. Since then, he has risen through the ranks into positions of increasing authority. Dave served as general manager of Roto-Rooter’s Charlotte, North Carolina, and Atlanta, Georgia branches before being promoted to Contractor Area Manager and later to Regional Vice President. Dave holds Master Plumber Licenses in Pennsylvania, North Carolina, and Georgia.

Dave Jones

Master Plumber, Roto-Rooter Plumbing & Water Cleanup

Expert Answer

It depends on the water heater and how many dial settings they have. However, you never want to exceed 120 F. That's the temperature where you're actually going to burn yourself.
Question

What if I want to set the water to a custom setting?

Dave Jones
Master Plumber, Roto-Rooter Plumbing & Water Cleanup
Dave Jones is a Professional Plumber and the Midwest Regional Vice President at Roto-Rooter Plumbing & Water Cleanup. In 1992, Jones joined Roto-Rooter as a drain service technician at the age of 18. Since then, he has risen through the ranks into positions of increasing authority. Dave served as general manager of Roto-Rooter’s Charlotte, North Carolina, and Atlanta, Georgia branches before being promoted to Contractor Area Manager and later to Regional Vice President. Dave holds Master Plumber Licenses in Pennsylvania, North Carolina, and Georgia.

Dave Jones

Master Plumber, Roto-Rooter Plumbing & Water Cleanup

Expert Answer

Unfortunately, you can't. The dial settings on your water heater are the only options you'll have available. If you have 4 settings on the dial, you've got 4 options for the temperature.
Question

Is it safe for me to change the temperature on an electric water heater?

Dave Jones
Master Plumber, Roto-Rooter Plumbing & Water Cleanup
Dave Jones is a Professional Plumber and the Midwest Regional Vice President at Roto-Rooter Plumbing & Water Cleanup. In 1992, Jones joined Roto-Rooter as a drain service technician at the age of 18. Since then, he has risen through the ranks into positions of increasing authority. Dave served as general manager of Roto-Rooter’s Charlotte, North Carolina, and Atlanta, Georgia branches before being promoted to Contractor Area Manager and later to Regional Vice President. Dave holds Master Plumber Licenses in Pennsylvania, North Carolina, and Georgia.

Dave Jones

Master Plumber, Roto-Rooter Plumbing & Water Cleanup

Expert Answer

Yes, although you do need to shut the power to the water heater off before you make the adjustment. Also, make sure that you adjust both the upper and lower thermostats to the same temperature and put the insulation back before you reattach the panels.

Warnings

If your water heater is wet or in a pool of water, do not touch it. Call a plumber, who can then assess the damage and danger.

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Be careful while adjusting your water heater. Never touch or move any open wires. If you do not feel confident in handling your water heater, call a plumber.

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