What Is The Downside of a Tankless Water Heater?

Tankless Water Heaters in San Antonio, TX

Are you looking to replace the water heater in your home but not sure whether a tankless or tank unit is best? The popularity of tankless water heaters has increased drastically in the past decade or so due to the many benefits they provide. Nonetheless, tankless water heaters do have a few minor downsides, which means you should think carefully about whether this type of water heater is right for your home. In this blog, we’ll look at how tankless water heaters work, compare them to tank units, and discuss their pros and cons.

An Overview of How Tankless Water Heaters Work

Traditional water heaters have a hot water storage tank and always keep the water inside the tank at the right temperature. Tankless units are often referred to as on-demand water heaters since they only run and heat when you’re calling for hot water. That means that the unit will turn on immediately when you turn the hot water on at a faucet or shower. The unit will then continue running and supplying hot water for as long as needed until you turn the faucet or shower off.

Both gas and electric tankless water heaters use a heat exchanger that absorbs heat from the gas burner or electric heating elements. As cold water flows through the water heater, the heat is transferred from the heat exchanger into the water. This quickly results in the water heating up to whatever temperature the unit is set to before it flows out of the water heater into your pipes.

Advantages of Tankless Water Heaters

One of the main reasons why so many people opt for tankless water heaters nowadays is that they work much more efficiently than tank water heaters. That means a tankless unit can effectively meet your hot water needs without using as much energy. Exactly how much energy you can save with a tankless water heater depends on your hot water demands, i.e., how many gallons you typically use each day. You’ll get the greatest savings if your average hot water usage is only around 40 gallons a day. However, only using this amount of hot water in a day is fairly rare since just one shower typically uses around 20 gallons. Still, even if your household usually uses around 80 gallons a day, a tankless water heater will likely use around 8-15% less energy than a tank unit.

Another major advantage that tankless water heaters have is that they last quite a bit longer. The average lifespan for a tank water heater is usually between eight and 15 years. The majority of tankless water heaters last for 20 years or more. Some units may even last for 30 years or more with proper maintenance. Part of the reason for the longer lifespan is that tankless units don’t have nearly as many components. They also experience much less wear and tear since they only run on demand. Tank units, on the other hand, will run for a few hours a day even when you’re away since they need to keep reheating the water they store.

The fact that tankless units don’t have as many components also means they are much easier to maintain. The main thing that needs to be done is to flush and descale the unit once or twice a year to prevent mineral deposits from building up on the heat exchanger.

Drawbacks to Having a Tankless Water Heater

Despite all of the major advantages tankless water heaters have over tank units, there are also a few negatives or areas where tank water heaters are slightly superior. Probably the biggest drawback to tankless water heaters is that they sometimes have a fairly long lag time. Since tankless units don’t have a readily available store of hot water, it takes a bit of time from when they turn on until the water flowing out of them reaches the desired temperature. Most units are capable of fully heating the water within around 10-15 seconds, but it can take a bit longer in winter when the water flowing into a house is colder.

Even though it may only take 10-15 seconds for the water flowing out of the water heater to reach the correct temperature, you may need to wait at least 30 seconds to a minute before hot water finally starts flowing out of the faucet or shower. This is because the hot water still has to travel from the water heater to whatever plumbing fixture you’re using. As the water travels to the fixture, it loses some heat since the pipes it moves through are quite a bit colder than the water. That means the pipes also need to heat up until the water finally starts flowing as hot as it should be. This is another reason why you’ll often have longer lag times in winter when the pipes in your home are colder.

Another factor that determines how long you’ll have to wait until the water gets hot enough is the distance between the water heater and the plumbing fixture. The greater this distance is, the longer the lag time will be. This is obviously because the water simply has to travel further. It’s also because there is a longer section of pipe that it has to move through, which means it will lose more heat until the pipes fully heat up.

If you’re concerned about the longer lag time you’ll experience with a tankless water heater, a good option is to install separate point-of-use units for each hot water fixture instead of having a whole-house unit. That means installing a point-of-use unit in each bathroom to supply water to the sink and shower. You may also have to install additional units in the kitchen and laundry room. Since each point-of-use unit is located within a few feet of the hot water fixtures, you’ll usually only need to wait a few seconds for the water to reach the right temperature.

The other drawback to tankless water heaters is that you’re more limited in terms of how much hot water you can use at a time. All tankless water heaters have a certain flow rate measured in terms of how many gallons of hot water they can produce per minute. Depending on the size of the unit, you may only have enough hot water to supply one shower and either the dishwasher or washing machine at the same time. If you try to use more fixtures at one time and exceed the unit’s flow rate, you’ll either end up with the water temperature fluctuating or just not being as hot as you want. That’s why it’s important that you evaluate your normal hot water needs and choose a unit with a sufficient flow rate to meet those needs.

For more than three decades, Rosenberg Plumbing & Air has been the company San Antonio residents and business owners have trusted for their plumbing, heating, and air conditioning. Our plumbers specialize in water heater installation, and we can explain the available options and help you determine which type and model is best for your home or commercial property. Contact us today to schedule an appointment with one of our experienced team members.

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