The Basics of Hot Water Heaters

Hot Water Now Heaters use a fuel source—electricity, natural gas, or non-renewable fossil fuel—to heat a large volume of water to a set temperature. Then the hot water is supplied to your faucets as needed.

Water Heaters

In a tank-type water heater, cold water enters through the dip tube at the bottom of the tank and the heating element turns on to heat the water to your thermostat’s setting. Hot water exits through the hot water outlet at the top of the tank and flows to your fixtures.

Hot water heaters are a big energy user, second only to heating and cooling your home. If you’re shopping for a new water heater, look for the bright yellow and black EnergyGuide label. This gives you the estimated annual energy consumption and operating cost, compared to other similar models.

Traditional storage water heaters use electricity, gas, propane, or fuel oil to heat the water in an insulated tank. These units come in various sizes from 20 to 80 gallons. They have thermostats that monitor temperature readings, and when the readings drop below a set level the heater kicks on to reheat the water. Energy-efficient storage water heaters have better insulation to reduce standby heat losses. Some have energy factors of 67% or higher, indicating they use less energy to heat the same amount of water.

Electric high-efficiency water heaters have an average lifespan of eight to fifteen years. They use about 65% less energy than standard electric water heaters. These models have smaller burners than used in whole-house gas water heaters, so they require no new gas lines for retrofit installations. They have first hour ratings of up to seventy-five gallons per hour. Small commercial-rated condensing water heaters are sometimes marketed as residential products, with an energy factor of up to 98% and input capacity greater than 75,000 Btu/hour.

Gas water heaters are generally more efficient than electric models, but their environmental impact is greater because natural gas is a fossil fuel. However, there are some high-efficiency gas water heaters available that reduce their environmental impact.

The best choice if you’re concerned about the environment is a demand or instantaneous water heater. These units don’t have a storage tank, but rather heat the water as it flows through the pipes, so it can be used right away. These units have lower initial costs than tanks, but their energy efficiency isn’t as good as that of conventional storage water heaters. They’re available with gas burners, propane or fuel oil engines, and heat pump systems. These units have high combustion efficiencies, but they still need to be mechanically vented.


Despite their simple shapes, Water Heaters have a lot of complex engineering on the inside. They are surprisingly ingenious devices for something so common and everyday on the outside. It takes an expert to design a well-functioning hot water heater.

The basic construction of a conventional hot water heater is a heavy metal tank with an insulating blanket. The tank holds a reservoir of hot water, usually up to 60 gallons (151- 227 liters). This is usually enough to supply most household needs. Typically the tank will have a dip tube at the top that is connected to the hot water outlet. The tank is heated by either an electric resistance or gas burner.

Both gas and electricity are commonly used to heat domestic hot water, but the most efficient is currently natural gas. This is because it is inexpensive and conveniently piped to most homes. Electric hot water heaters are also widely used, especially in North America and Europe. They use a 240-volt breaker panel and are easily installed in existing homes because they use the same voltage as most appliances and electrical service panels.

It is important that a hot-water system be properly designed for efficiency, and one of the most important aspects is the firebox or combustion chamber. It is necessary to have a large enough firebox for convenient stoking, but it must also be insulated and have a good airflow pattern to minimize the risk of water cooling and warping of the firebox doors.

The heat transfer rate of a water heater is another key consideration. It is necessary to be able to transfer as much heat from the fuel into the water as possible, and it is equally important to be able to store as much heat as possible for reuse. This can be done by proper sizing and design, as well as careful use of insulation.

Tankless and demand-type hot water heaters are also becoming increasingly popular because they can save energy and reduce heating costs. These appliances are sized to provide a sufficient amount of hot water for household use without the need for storage, and they can be sized to serve all or most outlets in a home. They can be powered by electricity, gas or solar energy.


Practicing proper water heater safety is one of the most important things you can do to protect yourself, your family and anyone who enters your home or business. By following these tips, you can extend the lifespan of your hot water heater and ensure that anyone in the building remains safe in the event of a problem.

One of the most common problems that leads to dangerous situations involving a hot water heater is improperly sized tanks. These tanks can reach unsafe temperatures and pressure levels, which could result in a fire or an explosion. To avoid this issue, you should have your tank inspected by a professional plumber.

It’s also a good idea to keep combustible materials and liquids away from your tank. You shouldn’t store items such as garbage, clothing or canisters of gas near the water heater. If the system ever leaks fumes, they may create a chemical reaction with these combustible items and lead to a catastrophic explosion.

In addition, it’s a good idea to have a carbon monoxide detector installed in your home. This device will detect any gas leaks and alert you to their presence, which can prevent potential carbon monoxide poisoning or other serious health issues.

You should also have a T&P valve (pressure relief valve) installed on your gas water heater. These small metal tanks are used to help relieve excess pressure within the tank. Without a T&P valve, water temperatures can increase and cause the tank to expand. As the water expands, it will build up pressure that cannot be released through a normal release valve. If your T&P valve becomes clogged with lint, it should be cleaned or replaced by a professional plumber.

Lastly, you should never use water from a hot water faucet when the handle is turned on. Hot water that is too hot can cause scalding injuries if someone isn’t careful when they turn on the tap. You can avoid this danger by setting the water temperature to no higher than 120 degrees Fahrenheit. If you’re not sure how hot your water is, you can test it with a meat or candy thermometer.


A water heater can last up to 12 years, but that doesn’t mean it won’t require maintenance. A good preventative maintenance plan includes regular draining, flushing and testing a pressure-relief valve. The pressure-relief valve protects the tank from over-pressurization, which can cause major damage and even explosion. Scaling or rust can block the valve, so it should be tested regularly to make sure it is working properly.

To test the T&P valve, turn off power to the unit and disconnect the gas line (if you have one). Connect a garden hose to the drain valve on the bottom of the tank and open it. Next, gently lift up the lever on the T&P valve. If air and water escape the pipe, the valve is working correctly. If not, the water heater is over-pressurized, which could damage the tank or rupture the venting system.

In addition to testing the T&P valve, drain and flush the water heater regularly to remove sediment that can build up. Also, inspect the plumbing connections to the water heater and fix any that are leaking or loose. For example, make sure the gas line is tightly connected and that there is enough clearance for the hot water vent pipe. Finally, examine the area around the water heater for signs of leaks and corrosion.

Leaks usually occur at the connections to the water supply or the venting system, so it’s important to use quality materials and proper techniques when installing plumbing. For instance, a compression fitting is easier for DIYers to install than copper pipes, which need to be soldered. If you see wet spots or rust on the outside of the water heater, it’s probably time to replace it.

Water heaters are complex machines with many moving parts, so professional inspection and maintenance is recommended. A facility management software solution can help you schedule, track and sustain all of your water heater maintenance tasks. Its digital calendars and reminders keep maintenance departments on track and help ensure that critical water heater maintenance doesn’t slip through the cracks.