3 Common Water Heater Issues That Cause Improper Heating

Water heater malfunctions can be one of the most frustrating experiences of homeownership. If you turn on the tap but don’t get hot water, the water heater is likely the root of the problem.


In some cases, your water isn’t completely devoid of heat but the water heater isn’t heating up as it should. In other cases, the water heater is working too well and creating scalding temperatures that could harm you or your guests. If it’s overheating, you’ll also be wasting energy and racking up bills in the process. Fixing the issue is not only a budget-friendly way to save energy in your home, but it will extend the life of your appliance.

Common Reasons for Lukewarm or Scalding Water

If your water is not hot enough or too hot, you’ll have to find the source of the issue that’s causing your water heater to act up. These symptoms could be an indication of a water heater that is on its last legs — or it could even be dangerous to have running in your home. Check for the following three common water heater issues to see if you can deploy a DIY water heater fix and have your appliance up and running in no time.

1. The Temperature Dial Is Set Incorrectly

Regardless of the type of water heater you have, most households don’t need to set the thermostat any higher than 120 degrees Fahrenheit. If your thermostat is set higher, reducing it to 120F will reduce the danger of scalding, slow mineral buildup and corrosion in your heater and pipes, and save energy.


You can test the current temperature that your water heater is producing by running tap water for three minutes into a cup and measuring the temperature. If it’s above 120 degrees, adjust the water heater temp by turning the dial and testing again until you reach the desired warmth. These dials are red and are typically located directly on the water heater.

2. The Temperature- and Pressure-relief (TPR) Valve Is Failing

The TPR valve is a safety feature installed in water heaters to prevent explosions if the water inside the tank were to overheat. If the water is overheating and the TPR valve fails, you have a dangerous situation on your hands. Failures can happen due to dirt, debris, freezing temperatures, corrosion, or rust.


You should test the TPR valve at least once a year. It’s located at the top of the water heater and can be tested by simply moving it up and down several times. If it’s working properly, you should hear a bubbling sound as some of the water is released into the drain connected to the TPR valve. If you don’t hear this sound, you can try to move it up and down again to clear some debris from the opening. If this doesn’t work, the valve may need to be replaced and we suggest you contact a professional. This should typically be done by a professional.

3. The Thermostat Is Malfunctioning

Less commonly, your water heater’s thermostats may be causing issues. Most likely, the aforementioned elements will be the culprit. However, if you have checked these parts and haven’t found the route of the problem yet, it may be worth it to undergo the more difficult task of diagnosing a thermostat malfunction. Of course, you can call a professional to do this for you as well.


Your water heater will always have at least one thermostat, but sometimes there is a thermostat for each heating element. Upper and lower elements are managed by these thermostats to redirect heating duties when one element becomes too hot. If the upper thermostat malfunctions, there will be no hot water at all. This could be the reason that your reset button is persistently tripped, mistakenly indicating that the water is above 180 degrees Fahrenheit due to a faulty thermostat.


To check the water heater thermostat, power off the electric supply. The thermostat will be located behind insulation in the electrical panel of your water heater. You’ll need a screwdriver and a multimeter, again. After correctly placing the multimeter on the terminals of the thermostat in question, perform tests at maximum and minimum temperature settings. If your multimeter doesn’t read zero, the thermostat is faulty and needs to be replaced.


Only attempt this diagnosis and repair if you are comfortable with your ability to work with electrical components safely and effectively. The thermostats are able to be replaced at home, but if you don’t feel comfortable working with electricity, call in a professional. You may also consider replacing both thermostats at once to prevent having to go in and replace another one at a later date.


Identify the type of thermostats for your make and model of water heater by consulting the manual or searching online. Purchase replacements and follow instructions for replacing the water heater thermostats. This involves flipping off the circuit breaker, testing to ensure no power is being transferred to the water heater. Then, you use a fourth-inch nut driver or flathead screwdriver and a #2 Phillips screwdriver to dismantle the current thermostats. You’ll have to remember which wires are connected to which terminals, so taking a picture can help. Then, you can attach the new thermostats to hopefully have your hot water heater working again in no time.

Testing the Water Temperature

After you make any repairs to your water heater, you will want to test to see if the issue has been wholly resolved. Typically, it takes about 30 or 40 minutes for the water to adequately heat up within the tank. After waiting this amount of time, you can test to see if the water is heating up as it should.


Let the hot water run for about one minute before sticking your hand under the tap to test the temperature. This will give you the most accurate representation of the water heater’s efficacy. If you’d like to take the safe route, you can use a candy or cooking thermometer to check the temperature. You will get a more accurate reading this way, as well. Simply stick the thermometer in a mug full of hot water and assess the new temperature.


Hopefully, your DIY fixes will result in the correct temperature. If the common issues aren’t the culprit, it’s worth taking a look at further possible complications or contacting a plumbing professional. Once it is properly running, you can have peace of mind about your energy-saving practices and begin to reap the benefits of a functional water heater.

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