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How Do Tankless Water Heaters Work?

Tennessee Standard
July 29, 2022

Traditional

     The traditional method of heating water is to keep a 30-80 gallon tank heated to 120+ degrees at all times. As hot water is used, fresh cold water flows in to replace it, and the heating elements (for electric) or burners (for gas) engage to get the new temperature of the stored water up to 120 degrees again.

     Also, as the water in the tank is unused, the heating components still have to engage from time to time to keep the water up to desired temperature.

     This method has been tried and true for over 100 years, but has its weaknesses when it comes to efficiency. 

Modern

To solve some of these problems, the industry came up with the solution of the “tankless” (or on-demand) water heater, a technology which has been an incredible answer to some of the questions of the past decades on how to heat water more efficiently.

Although the technology had some wrinkles to perfect from its original conception in the early 1900s, the tankless water heaters on the market today are some of the most cutting-edge, innovative products in the home industry.

Almost all new high end homes will, by default, include a tankless water heater, and homeowners are regularly making the decision to upgrade their old tank-style heater and enjoy the many benefits of tankless technology. Perks of investing in a tankless water heater range from luxury end-user experience to overall financial savings, but how do they work, and what are the key features that give them so much appeal?

Tankless water heaters can be powered by either natural gas, propane, or electricity. In electric units, when hot water is turned on at a fixture, cold water flows through the unit and is rapidly heated by several high-powered elements, reaching desired temperature before leaving the outlet side of the heater.

When water is turned off, an internal flow sensor detects the change and stops heating the coils. While very innovative, electric tankless water heaters are extremely susceptible to hardness in the water supply, and the elements will quickly scale over and break down without sufficient water treatment solutions. 

Gas tankless heaters work similarly, but instead of heated metal coils, the water passes through a heat exchanger, which is a series of metal tubes heated by gas burners. Because there are no heating elements touching the water, the heat exchanger is much less susceptible to flaws in the water.

Hardness and chlorine in water always lead to shorter lifespan of plumbing fixtures, but gas tankless heaters will still function properly without water treatment. The gas unit is our tried and true champion of tankless water heaters. If you are considering upgrading to tankless, the gas models are the best route to take if you have gas available in your home.

Tank vs. Tankless

They both bring hot water to your faucets, so what is the big difference between the two options?

Endless vs. Limited Hot water

     Because tank-style heaters have a certain amount of water it keeps heated, you will only be able to use the capacity of the tank before hot water “runs out.”

     However, because tankless heaters heat the water as it passes through the unit, it provides perfectly heated water on demand, when you need it. Different sizes of units will be able to facilitate different levels of demand depending on the number of fixtures in the home, and will never run out of hot water.

Longer Lifespan

     While tankless water heaters are a bigger upfront investment than tank-style water heaters, they pay dividends in savings throughout their lifespan. A tankless can cost 2-3 times more than a standard tank water heater, but it will last two to three times longer.

     The average lifespan of our recommended gas tankless water heaters is anywhere between 15-20 years if maintained properly, while most tank-style heaters produced today only last 8-12 years before having issues.

     The increased lifespan alone will save you money on replacement tanks and labor, not to mention the saved headaches from having no hot water and relying on a plumber to get your system working properly when the old tanks break down.

Energy Savings

Essentially the tankless has already paid for itself by its much longer life expectancy, but the savings continue further because much less energy is used to heat the water in your home. Whether your tankless heater is gas or electric, you will save more on utilities because power is only used when hot water is being used, instead of a tank-style constantly burning energy to keep a storage tank up to temperature at all times. Tankless water heaters uses 24-34% less energy than its traditional counterpart. 

Takes Up Less Space

     For those struggling with limited space in your mechanical room, garage, or attic, tankless heaters use up much less space.

     The units are often wall-mounted and a fraction of the size of traditional tank-style water heaters, so they free up a noticeable amount of space in your home. These heaters can even be mounted on an exterior wall for houses that are really short on space. 

More Installation Location Options

     There is only one place you can put a traditional water heater, but tankless heaters can be installed on pretty much any "water wall" in the house. Their small size and ability to be mounted also clear up extra floor space for easier maneuvering in tightly cramped utility rooms. 

Environmentally Friendly

     Many households choose to switch to a tankless heater because it is better for the environment. Of course, it saves on natural resources because they are more efficient than tank-style heaters, but another environmental benefit is often overlooked.

     These appliances are smaller and have three times the life that traditional water heaters have, which means the parts that can't be recycled stay out of the landfill longer and take up less space when they get there. 

Modular Repairs

     While tank water heaters often times fail because of a leaking tank that cannot be repaired, tankless water heaters are built modularly, and repairs are much more likely to be successful because parts can be swapped out without needing the integrity of a tank.

Can I Install It Myself?

     There is nothing wrong with saving money by doing your own installation on a lot of appliances, but a tankless water heater shouldn't be one of them. They are complex units, and a trained professional is your best bet to get the most out of your tankless water heater.

     In fact, most of the negative feedback online about tankless water heaters are either due to older models manufactured before the technology was perfected, or due to improper installation resulting in failure of the unit.

     With factors such as water supply configuration, incoming gas/electric, condensation drains, water hardness, exhaust ventilation (in gas models), installing a tankless water heater correctly is a technical and challenging process.

     One wrong configuration can shorten the life of your water heater immensely, or keep it from working at all. The extra money you spend on labor for a professional installation will more than pay for itself in the long run when you have a tankless water heater that runs flawlessly for decades. 

Treat Yourself to Tankless

     If you are in the market for a new water heater or are just looking to upgrade to a more energy-efficient model, contact us for experienced and professional installation.

     The benefits of this technology are nearly endless, just like your hot water supply will be. You will love the peace of mind knowing that your hot water will never run out, all the while saving money on energy and plumbing expenses!

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