Tankless water heaters have long been the most common option in places like Europe and Japan, but most people in the US still use traditional water heaters. A traditional water heater constantly stores a large volume of water within its tank, which creates the potential for major leaks and other issues. Tankless units overcome the most common water heater issues as they don’t store any water and only heat whenever hot water is called for. To help you understand the difference, let’s take a look at exactly what tankless water heaters are and how they work.

Understanding How Tankless Water Heaters Work

Tankless water heaters are often referred to as on-demand heaters. These are small units that are typically mounted on a wall with a cold water line coming in and a hot water line coming back out. Whenever you turn the shower or faucet on to hot, the unit almost instantly works to heat the water that flows through it. These units can run off gas (natural gas or propane) or electricity. In either case, the process they use to heat water is essentially the same and relies on a process known as heat exchange.

When hot water is called for, the unit kicks on and instantly begins warming a heat exchanger. In a gas unit, a gas burner is used to supply the heat. With electric units, electricity flows through a resistance coil that supplies heat to the exchanger. Cold water then immediately begins flowing into the unit and through the heat exchanger. This transfers heat energy to the water and instantly raises it to the desired temperature. An internal thermostat constantly measures the heat exchanger to ensure the water is heated to the set temperature.

As long as the hot water tap is open, heat energy continues to flow into the exchanger. This means that you essentially have an endless supply of hot water. As soon as the tap is closed, the gas or electricity shuts off, and the unit stops using energy until hot water is called for again.

Both gas and electric traditional water heaters also use the same types of heat exchangers. The difference is that these units constantly keep the water inside the tank heated to whatever temperature the unit is set at. Whenever you use any hot water, cold water flows directly into the bottom of the tank to replenish it. The unit then instantly turns on to heat this new water.

Although the tank is insulated, the unit needs to run frequently to maintain the set temperature. Even if you’re not using any water, it will still need to heat at least once an hour. This means that it is constantly consuming energy whether you’re using any hot water or not.

Types of Tankless Water Heaters

Tankless water heaters can be either point-of-use or whole-house units. Most of the gas units are whole-house, but electric units can be either. Whole-house units obviously supply hot water to all plumbing fixtures in the building, and these are the most common type used in residential plumbing systems.

With a whole-house unit, there will always be some lag time before you have hot water flowing out of the tap. The further away from the unit the fixture is, the longer the lag time will be. The amount of lag time also depends on how cold the water coming into your house is and the temperature of your pipes. You usually won’t have to wait more than 15 to 30 seconds. Still, it can sometimes take up to a minute or two if the water is especially cold or the tap is far away.

Point-of-use heaters are smaller and only supply water to one faucet or shower. These units are small enough that they can fit under your kitchen cabinet or inside a closet, which means they can be installed virtually anywhere you need. These are often used in commercial or industrial settings where you only need hot water in one location. Some people also use them in their homes to supplement their existing hot water supply.

For instance, if you have a traditional water heater with a small-volume tank, you could install a tankless heater in the bathroom that supplies your shower only. This can also help if you have any fixtures that are far away from your central water heater. In this case, the tankless unit would drastically reduce how long it takes for hot water to flow and help to reduce water waste.

Benefits of Going Tankless

Tankless water heaters provide a number of important benefits that makes them a great choice compared to traditional units. However, it is important to note that tankless units are more expensive to purchase and install. On the other hand, they use far less energy and will typically have a much longer lifespan than traditional units. This usually more than offsets the higher initial costs.

Traditional water heaters typically won’t last for more than 8 to 12 years at the most. You may even be able to get 15 years out of the unit, but we don’t recommend ever trying. The older the unit is, the more likely it is that the tank will become corroded and potentially flood your house.

Both gas and electric tankless heaters should easily last for 15 to 20 years, and some may even go for as long as 30 years. This means that you may only need to purchase one tankless unit that will last as long as two traditional water heaters.

The fact that tankless water heaters don’t store any water means that they also use much less energy and don’t suffer from the same issues with leaking as traditional units. Tankless water heaters can reduce your energy costs by anywhere from 10 to 40% depending on how much hot water you use every day. Your savings will be highest if your home uses less than 40 gallons a day. However, the savings are generally minimal if you use more than 80 gallons per day. In this case, you may want to consider a traditional unit.

One other benefit of tankless units is that you don’t need to worry about using up all of the hot water. When you use lots of hot water in a short time, you can easily drain the tank on a traditional unit. When this happens, you may need to wait anywhere from 30 minutes to two hours before you’ll have hot water again. This is never an issue with tankless units since they can continue to run as long as needed. As long as your electricity or gas doesn’t go out, you’ll always have hot water whenever you need it.

Professional Plumbing Services in San Jose

At Plumbtree Plumbing & Rooter, we provide the full spectrum of plumbing services to customers in San Jose and the Greater Silicon Valley. Our plumbers help with all types of plumbing repairs, service and install both traditional and tankless water heaters. If you’re experiencing a major leak or any other plumbing emergency, we are available 24/7. We also specialize in drain cleaning, rooting, hydro-jetting and water, gas and sewer line services. For more information on tankless water heaters, or if you need any plumbing service, give Plumbtree Plumbing & Rootera call today.

Josh Gibson

Hi, I’m Josh. I’ve been around plumbing my whole life. When I was 5-6 years old my family built a home where I did a lot of the sanding of copper pipe and definitely some playing in the mud. Plumbing is a major part of my family as I am a fourth-generation plumber. The skills I bring to the job are a good technical knowledge of plumbing and code requirements. I am often complimented on my hands-on problem-solving skills.
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