Common Causes of Hot Water Heater Overheating (Plus Fixes)

The hot water in the tank should have a temperature cap that limits how hot the water may be adjusted. If there is no safety system to prevent the water heater from overheating, hot water can cause burn injuries to your family.

To maintain your hot water heater in good working order, make sure it doesn’t grow much hotter than usual.

Water Heater Overheating: Causes and Solutions

Suppose your water heater suddenly produces too much hot water. In that case, it’s most likely due to an incorrect temperature setting, a faulty thermostat, high mineral content, or a clogged pressure relief valve. Each of these concerns can cause the water from the faucet to be overly hot.

Temperature Setting Too High

If the temperature setting is too high, it may cause the water heater to heat up too much. If your water heater is causing the water to be too hot, there’s a good chance you have the temperature setting set higher than you need it.

The first step is to reset your temperature setting to the correct temperature.

While the temperature setting may not be the root cause, lowering the temperature setting is usually the quick fix that can resolve this issue.

Malfunctioning Thermostat

A malfunctioning thermostat might be the cause of your water heater unexpectedly becoming hot. The thermostat regulates the water heater’s on-and-off cycles. If the thermostat fails, a safety feature causes the thermostat to turn off the power to the boiler elements.

The elements will heat the water if the thermostat safety function fails. Unfortunately, this can result in dangerously high water temperatures. If this happens to your thermostat, the most straightforward solution is to replace it.

Minerals Buildup

Another reason water coming out of your faucet might be too hot is because of the minerals that have built up in the tank. While this problem is less likely than a malfunctioning thermostat, it can happen. There are ways to prevent minerals from building up in your water tank. First, you’ll want to drain the water from the tank. You can do this by opening the drain valve.

To head off a mineral buildup before it becomes too bad, you’ll want to periodically flush the tank by draining 2 or 3 gallons of water from the tank every few months.

A buildup of minerals at the bottom of the tank can be caused by the water in your home being too hard. You can prevent unnecessary buildup by adding a water softener to your washing machine.

Blocked Pressure Relief Valve

Blocked pressure relief valves can cause water heater problems to occur. A blocked pressure relief valve allows too much pressure to build up in the water heater. This can cause the water heater to overheat and make the water too hot. You’ll note the problem if you see your water heater has been working harder and longer than expected.

You can check the valve by taking off the pressure relief valve cap and seeing if it’s blocked. If the valve is blocked, there’s a good chance you can clear the blockage by using a pin or paper clip to poke something through the hole.

If you can’t clear the blockage, you may need a professional from Legacy Heating and Cooling to clear the blockage for you.


A hot water tank is a long-lasting appliance that can provide many years of hot water. However, problems can occur with a water heater over time. If your water heater is overheating or making the water too hot, it’s likely due to a problem with the temperature setting, thermostat, or pressure relief valve. Rheem and Bradford White are two reliable hot water tank brands!

At Legacy Heating and Cooling, we give our clients comprehensive and cost-effective HVAC products with our decades of experience. This is why getting our team of qualified technicians to inspect and treat your problems is the best course of action. If you need to repair your home’s hot water tank or heater in Edmonton or Calgary, contact us at 780-733-1256 or 403-451-1337 today!

HVAC Brands We're Proud to Carry

Legacy only uses the most efficient and cost-effective HVAC products. We pride ourselves on putting quality and customers first! We will equip your new home with the best HVAC system and offer the most reliable residential heating service in Edmonton and Calgary.

Contact Us Today

We’ll help you find the right heating and air conditioning system for you and your budget.

Edmonton Area 780-733-1256 Calgary Area 403-451-1337

Honesty, Integrity, Legacy