No Hot Water In House? 7 Common Causes Explained

No one likes to take a cold shower! When you have no hot water in your house, you're very motivated to solve the problem. Thus the reason you are frantically searching online for reasons why your water heater is not working.

Lucky for you, we're going to explain why your water heater is not working and also provide you with some water heater troubleshooting advice. In no time, you'll have a much better idea what might need to be fixed.

WARNING: Always exercise extreme caution when operating, repairing or maintaining your water heater. If you have an electric water heater, always turn off the power to your water heater before attempting to repair anything. For gas water heaters, make sure there are no gas leaks present before continuing.

Are You Sure Your Water Heater Is Not Working?

Before addressing the reasons you have no hot water in your house, there are a few things you should consider. Sometimes, the water heater works properly, but you may still not be getting enough hot water. Here are three preliminary reasons you may not be getting enough hot water in your home.

No Hot Water Due To Thermostat Setting

One reason you may not have hot water in your house is because you set your water heater temperature too low. To save energy or avoid scalding hot water, some homeowners set their water heater thermostats too low. 

Most water heater manufacturers recommend you set the temperature of your water heater around 140 degrees. However, the EPA recommends the temperature to be set to 120 degrees on the low end. Additionally, setting your water heater thermostat below 120 puts you at an increased risk of Legionella Disease.

gas water heater thermostat

Thermostat on gas water heater on gas control valve

thermostat in electric water heater

Thermostat on electric water heater on upper element

Therefore, check the thermostat on your water heater. Try increasing the temperature and give your water heater some time to heat. If you still have no hot water in your house, keep reading.

No Hot Water Due To Wrong Size Water Heater

Water heater sizes range from 40 gallons to 80 gallons in size. A 40 gallon water heater is fine for a single person or a married couple. But once you add a few children into the mix, you need a bigger water heater.

Family Size

Water Heater Size

2-4 People

40 Gallons

3-5 People

50 Gallons

4-6 People

65 Gallons

6+ People

80 Gallons

You will run out of water during peak demand times if your water heater is too small. So you can try adding a water heater booster or installing a new water heater that is big enough for your family.

No Hot Water Due To A Mixing Valve

If you don't have hot water in one specific location, look for a mixing valve. A mixing valve is used to mix hot and cold water so that you can avoid scalding hot water. If you recently purchased a home and notice the water is not hot in a specific location, it might be that you have a mixing valve installed.

mixing valve can cause no hot water in house

A mixing valve under the sink connected to a shower, causing no hot water in shower

Reminder: Check Your Water Heater Warranty

If you end up needing to repair your water heater, it's important to check your warranty. Most water heater manufacturers include a warranty. However, keep in mind that even though the warranty often includes parts, you'll still need to pay for labor. 

Most manufacturers have a phone number you can call to ask if the water heater is still under warranty. More than likely, you'll need to provide the serial number and model number of your water heater. So write this information down before contacting the manufacturer.

If you get your water heater repair in Orlando done by Pro-Tech Air Conditioning and Plumbing, we will take care applying any credits or discounts. Then you'll only pay for labor and any non-warranty parts that are needed.

If Your Gas Water Heater Has No Hot Water

If you have no hot water in your house and you have a gas water heater, there are several things that could be a problem.

Inspect Your Pilot Light

If you have a gas water heater, the pilot light will be on the bottom of the water heater behind an access panel. The pilot light should always be lit. The purpose of a pilot light is to ignite the gas needed for your water heater to heat. If your hot water heater is not working, then you should inspect it and look for the following problems.

Pilot Light Is Not Lit

A little wind can cause the pilot light to go out. Therefore, make sure that the pilot light is lit. If not, then relight the pilot light. Once the pilot light is lit, make sure that it stays lit and that you have a blue flame. Your gas water heater will produce no hot water if you aren't maintaining a constant blue pilot light.

Pilot Light Keeps Going Out

If the pilot light keeps going out, that is a sign that your thermocouple may need to be replaced. The job of the thermocouple is to detect if the pilot light is lit or not. If the pilot light is not lit, the thermocouple will prevent gas from being released. However, if the thermocouple is no longer functioning properly, it may think that your pilot light isn't lit and automatically cut off the gas supply, thus making your pilot light go out again.

Pilot Light Is Yellow

The pilot light should have a blue appearance. A yellow flame means that there is not enough oxygen available. There could be dangerous levels of carbon monoxide in the room. It is also possible that the pilot light opening is dirty or there is a draft in the room disturbing the pilot light. If you find that you have no hot water in the house, make sure you have a nice blue pilot light.

Yellow pilot light indicating poor oxygen mixture

blue pilot light indicating good oxygen level

Replace The Thermocouple

As mentioned above, the job of a thermocouple is to detect if the pilot light is lit or not. If it’s broken, it will stop the flow of gas to your water heater. You’ll have no hot water until you replace the thermocouple.

Inspect Gas Lines

If you have no hot water in the house, it could be a sign of problems with the gas line that need to be addressed.

Replace The Gas Control Valve

Your water heater will produce no hot water if the gas control valve is faulty. The job of the gas control valve is to manage the flow of gas to the water heater. It’s located toward the bottom of your water heater and looks like a little box mounted to the water heater. Your gas lines will connect to the gas control valve. If you have no hot water in the house despite having a nice blue pilot light, it could be a problem with the gas control valve. 

picture of a water heater gas control valve

Check The Gas Supply Line

Your gas water heater won’t work if it doesn’t have gas. So be sure to check the gas supply line. You may have accidentally turned the gas off. If this happens, you’ll have no hot water in your house. Therefore, check the supply line and make sure the gas it not turned off. Also, check the gas line to make sure there aren’t any kinks that are blocking the flow of gas to your water heater.

Check For Gas Leaks

A gas leak can be dangerous and will cause your water heater to stop working. If you have no hot water in your house, be sure to check for a possible gas leak immediately.

There are at least 3 ways to check for a gas leak. First, you can purchase a gas leak detector from the store. This will alert you to a gas leak. Second, a gas leak will smell like rotten eggs. Third, gas leaks sometimes cause a hissing sound.

If you detect any signs of a gas leak, turn the gas off and leave immediately. Once you are a safe distance from your home, contact your gas company for help.

Contact Your Gas Company

While unlikely, the gas company may have turned off the gas supply to your house temporarily. Call the gas company and tell them you have no hot water. Ask if they have turned off the gas in your area. If so, wait for them to turn the gas back on before lighting your pilot light and testing your hot water.

If Your Electric Water Heater Has No Hot Water

If you have no hot water in your house and you have an electric water heater, there are several probably causes.

Reset The Breaker

If you don’t have hot water, the first place to look is your electric panel. Look for the switch that controls power to your water heater. When a breaker trips, it positions itself toward the middle of the switch rather than to the “on” position. If the water heater trips the breaker, turn the breaker to the “off” position and then back to the “on” position. Wait for 30 minutes to an hour and check your water temperature again. More than likely this will fix the problem.

circuit breaker with water heater label

Electricians often mark a control panel breaker with “W/H” to show that it powers the water heater.

If the breaker keeps tripping, this means that the water heater is drawing too much energy. Therefore, continuing to reset the breaker is not a permanent solution. A faulty heating element or thermostat may cause this. You should contact a plumber to troubleshoot the water heater and possibly replace your water heater if necessary.

Reset Your Thermal Cutoff Switch

Manufacturers equip your water heater with a thermal cutoff switch. The thermal cutoff switch turns the water heater off if the internal water temperature gets too high. This is one of the most common reasons you have no hot water in your house.

The easiest way to check the thermal cutoff switch is to turn the power off to your water heater at the electric panel. Once the power is off, you can remove plate covering your upper thermostat. The thermal cutoff switch is almost always on the upper thermostat. To reset the switch, look for a small button (normally red) on the upper thermostat. Push the button. If you hear a “click”, this proves that the thermal cutoff switch caused your water heater to stop working.

The thermal cutoff switch will keep turning the water heater off if there is some underlying issue that needs to be resolved. An experienced plumber can troubleshoot the water heater in this case.

hot water heater not working due to thermal cutoff switch

a thermal cutoff switch causes no hot water in house

Replace Faulty Thermostats

Electric water heaters have an upper and lower thermostat. If the thermostats detect that the water needs to be heated, they will turn on the internal heating elements. However, if one or both of the thermostats are not functioning, you will either have no hot water or you don’t have enough hot water. Replacing the faulty thermostats will fix the problem in this case.

Replace Faulty Heating Elements

The heating elements heat the water inside of your water heater. But if the heating elements aren’t working, you’ll have no hot water. The heating elements can become damaged over time because of a lack of maintenance and a buildup of sediment in the tank. 

heating element

This water heater had no hot water because a faulty heating element

heating element for water heater

Sediment builds up on your heating element and can cause your water heater to stop working

If You Still Have No Hot Water

You can do some water heater troubleshooting on your own if you know how to do it safely. If you have tried some of the DIY steps and you still don’t have any hot water, contact a plumber for help. Pro-Tech has a team of plumbers in Orlando and Central Florida trained to repair or replace water heaters safely.

Considering the age of your water heater, it may be a smarter option to replace your water heater rather than put money into fixing an old water heater. We offer free water heater estimates.

Whether you think it’s best to repair or to replace your water heater, Pro-Tech is here to help. Call us at (877) 416-4727 to get started.

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