Repair

Water heater high temperature shutdown causes and how to fix

Discover the causes of high-temperature shutdowns with your water heater and learn how to fix them with our expert tips.

Are you tired of your water heater shutting down unexpectedly, leaving you without hot water for hours? If so, you’re not alone. High temperature shutdown is one of the common issue among hot water heater problems that many homeowners face, and it can be frustrating to deal with. But don’t worry, we’ve got you covered.

In this comprehensive article, we’ll walk you through everything you need to know about water heater high temperature shutdown. From understanding what causes it to happen, to how to fix it, we’ll cover it all. You’ll learn about the different types of water heaters, common symptoms of high temperature shutdown, and tips for preventing it from happening in the future.

Our expert team has compiled a list of the top reasons why your water heater might be shutting down, including issues with the thermostat, a faulty high-limit switch, and even sediment buildup in the tank. We’ll also provide step-by-step instructions for diagnosing and fixing these problems, so you can get your hot water back up and running in no time.

But that’s not all. We’ll also share some practical tips for maintaining your water heater to prevent future issues. You’ll learn how to drain and flush your tank, check for leaks, and test the pressure relief valve. Plus, we’ll provide a handy table comparing different types of water heaters, so you can determine which one is best for your home’s needs.

What is High Temperature Shutdown in water heaters

High temperature shutdown is a safety mechanism built into many modern water heaters. Essentially, it’s a failsafe that kicks in when the water temperature inside the tank becomes dangerously high. When this happens, the water heater shuts off the pilot light and burner and put the heater into standby mode or error mode to prevent overheating, which potentially leads to a tank or pipe explosion or causing other dangerous situations which can cause significant damage to your home.

Common Causes of Water Heater High Temperature Shutdown

Several factors can cause water heater high temperature shutdown. These include:

  • Thermostat Malfunction: If the thermostat is faulty, it may not sense the water temperature correctly, leading to the water heater overheating.
  • Temperature setting: Check the temperature setting on the thermostat and adjust it to between 120°F to 140°F. If the thermostat is set too high, it can cause the water to overheat and trigger the high-temperature cutoff switch.
  • Sediment Build-Up: Sediment can build up in your water heater, causing the unit to work harder than usual to heat the water. This extra work can lead to overheating and high temperature shutdown.
  • Faulty Pressure Relief Valve: The pressure relief valve is responsible for releasing excess pressure in the water heater. If it’s faulty, the pressure can build up, causing the unit to overheat.
  • Dirty Burner: A dirty burner(gas water heaters) or heating element(electric water heaters) can cause the water temperature to rise above the maximum limit and trigger the high temperature shutdown.
  • Insufficient Ventilation: Inadequate ventilation in your water heater’s room can cause heat to build up, leading to overheating.

Symptoms and Troubleshooting of Water Heater High Temperature Shutdown

Thermostat Malfunction or failure

A malfunctioning thermostat can also cause high-temperature shutdown in a water heater. The thermostat controls the temperature of the water in the tank. If the thermostat is faulty, it may not be able to regulate the temperature, causing the water to overheat and triggering the high-temperature cutoff switch.

Symptoms of a Faulty Thermostat:

  • Water is too hot or not hot enough
  • Burner not turning ON or OFF
  • Water temperature fluctuates
  • Pilot light not staying lit

How to Troubleshoot a water heater Thermostat:

gas water heater thermostat with controller

  1. Turn off Power and Gas: Turn off the power and gas to the water heater by switching off the circuit breaker or unplugging the unit.
  2. Remove Access Panel: Remove the access panel on the side of the water heater tank to expose the thermostat.
  3. Test Temperature Setting: Turn ON the heater and Turn the thermostat up to its highest setting and wait for the water to heat up. Use a thermometer to test the water temperature at the hot water faucet. The water temperature should be around 120°F to 140°F.
  4. Test the Thermostat: We cannot access thermostat in gas water heater control unit. In this case we need to take the control unit out and check the backside probe entering into the tank. if it looks damaged or worn out, it needs to be replaced.
  5. Replace Thermostat: If the thermostat fails temperature setting test, it needs to be replaced. You can change it by yourself if you have good knowledge of your water heater or else it is highly recommended to contact a professional to replace the thermostat.

Faulty Pressure Relief Valve

Another reason for high-temperature shutdown in a water heater is a malfunctioning pressure relief valve. The pressure relief valve is designed to open and release pressure when the water heater’s pressure reaches a certain level, preventing the water heater from exploding. If the pressure relief valve is faulty, it can cause high pressure in the water heater, which can trigger the high-temperature cutoff switch.

pressure relief valve on water heater

Symptoms of a Faulty Pressure Relief Valve:

  • Water is too hot
  • Leaking water from the pressure relief valve
  • Rust or corrosion on the pressure relief valve

How to Test a Pressure Relief Valve:

  1. Access Pressure Relief Valve: The pressure relief valve is located on the top or side of the water heater. It is a brass or copper valve with a lever or handle.
  2. Open Valve: Lift the lever on the pressure relief valve to open it. You should hear a rush of air or see water coming out of the valve.
  3. Release Valve: Release the lever on the pressure relief valve and observe if it closes properly.
  4. Check for Leaks: Check for leaks around the pressure relief valve. If there are any leaks, the valve needs to be replaced.

Dirty Burner

A dirty burner can cause the water temperature to rise above the maximum limit and trigger the high temperature shutdown. Symptoms of a dirty burner include water that is too hot or not hot enough, the burner making unusual noises, and a yellow flame instead of a blue flame.

gas water heater burner at the bottom of the heater

Steps to clean the burner of a gas water heater

  1. Turn off the gas supply: Before beginning any maintenance on your gas water heater, you must first turn off the gas supply to the unit. Locate the gas valve near the bottom of the tank and turn it to the off position.
  2. Turn off the water supply: Once the gas supply is turned off, turn off the water supply to the water heater by closing the valve located on the cold water supply pipe.
  3. Remove the burner assembly: Locate the burner assembly, which is typically located at the bottom of the water heater tank. You may need to remove a metal plate to access it. Use a wrench to loosen and remove the bolts holding the burner assembly in place, and then gently lift the assembly out of the tank.
  4. Clean the burner: Use a soft-bristled brush or a vacuum cleaner with a brush attachment to gently clean the burner and surrounding area. Be sure to remove any dirt, debris, or rust buildup on the burner. If there is heavy buildup, you may need to use a wire brush to remove it.
  5. Clean the pilot tube and orifice: Use a small brush or a piece of wire to clean the pilot tube and orifice. Be sure to remove any debris or buildup that may be clogging the tube or orifice.
  6. Reassemble the burner assembly: Once the burner assembly is clean, reassemble it in the reverse order in which it was removed. Make sure the assembly is securely in place and tighten the bolts to hold it in place.
  7. Turn on the gas and water supply: After the burner assembly is reassembled, turn the gas and water supply back on. Make sure there are no gas leaks and that the pilot light is lit properly.

Sediment Build-Up

Sediment buildup can also cause high-temperature shutdown in a water heater. Sediment is formed when minerals and other debris in the water settle at the bottom of the tank. Over time, sediment buildup can cause the water heater to overheat and trigger the high-temperature cutoff switch.

Symptoms of Sediment Buildup:

  • Reduced hot water flow
  • Water Overheating
  • Water heater takes longer to heat up
  • Strange noises coming from the water heater

How to Prevent Sediment Buildup:

  1. Flush the Tank: Flushing the tank regularly can help prevent sediment buildup. This involves draining the tank and flushing out the sediment. Homeowners can do this themselves by following our detailed guide on how to flush a water heater or hire a technician to do it.
  2. Install a Water Softener: Hard water can contribute to sediment buildup in the tank. Installing a water softener can help prevent this by removing the minerals from the water.
  3. Use a Sediment Filter: Installing a sediment filter on the water supply line can also help prevent sediment buildup in the tank.
  4. Consider a Tankless Water Heater: Tankless water heaters do not have a tank and are less prone to sediment buildup. But still they have heat exchanger unit where minerals buildup over time in the pipes, flushing is need to be done.

Clogged Vent

A clogged vent can cause the water heater to overheat and trigger the high temperature shutdown. Symptoms of a clogged vent include a pilot light that goes out frequently, water that is too hot or not hot enough, and a burner that makes unusual noises. To troubleshoot a clogged vent, you should inspect the vent for any obstructions such as debris or birds’ nests. You can remove the obstruction manually or use a specialized vent cleaning tool to clear the vent.

How to Prevent High Temperature Shutdown in water heaters

Preventing high temperature shutdown in your water heater is relatively easy if you follow a few simple steps:

  1. Regular Maintenance – Schedule regular maintenance appointments with a qualified technician to keep your water heater in good working order.
  2. Replace the Thermostat – If your thermostat is malfunctioning, replace it as soon as possible to prevent high temperature shutdown.
  3. Flush the Tank – Flushing your water heater tank periodically can help prevent sediment buildup.
  4. Monitor Usage – Be mindful of how much hot water you’re using, and don’t leave it running for extended periods.

Conclusion

High temperature shutdown is a safety feature that’s built into many modern water heaters. While it can be a nuisance, it’s an essential failsafe that can help prevent dangerous situations from arising. By following the tips outlined in this article, you can prevent high temperature shutdown and keep your water heater running smoothly for years to come.

If you have any doubt please comment below, We are happy to help.

TanklessHelp Staff

TanklessHelp Staff has an experienced writers and researchers in the field of water heating technology. With a background in HVAC and plumbing, Tanklesshelp staff has in-depth knowledge in many types of waterheaters in America and Canada. They have a passion for educating homeowners and businesses on solving easy to hard repairs and guide them on how to maintain them to save money.

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