Are you considering upgrading to a tankless water heater but not sure if it’s worth the extra cost? In general, tankless water heaters are quite a bit more energy efficient than traditional storage tank water heaters. That’s mainly because it takes more energy to keep the water in a storage tank constantly hot than it does to just provide hot water on demand as a tankless water heater does. Nonetheless, the fact is that electric tankless water heaters can sometimes consume a massive amount of energy. In this article, we’ll look at the energy usage of electric tank and tankless water heaters and also discuss how they compare to gas tankless water heaters.

Average Energy Consumption of an Electric Tankless Water Heater

Electric tankless water heaters technically have an extremely high energy demand when compared to electric storage tank water heaters. For a family of four, you’d normally need around a 60-gallon storage tank water heater, and the electricity consumption for a unit this size is typically around 4-4.5 kilowatts per hour (kWh).

The capacity of a tankless water heater is measured in how many gallons of hot water it can supply per minute (GPM). For a larger household with two bathrooms and a kitchen, you’d usually require a tankless unit with a flow rate of at least 4-6 GPM. A tankless unit with this sort of flow rate will typically have a maximum electricity consumption of anywhere from 20 to 36 kWh, which is many times more than what even a large AC or heat pump uses. If you have a smaller home with only a single bathroom and you rarely have multiple fixtures using hot water at the same time, you can often get away with only a 10- to 15-kWh unit.

The only thing is that electric tankless units rarely operate at their full capacity. They do draw the full amount of power when first starting up, but then the amount of power they consume usually drops significantly within a minute or so once the electric heating elements are fully hot. Most of the time the unit will never run at more than 50% capacity, meaning its electricity consumption is cut at least in half.

Nonetheless, the exact amount of electricity the water heater will use at any given time depends on several different factors. Two of the biggest ones are the temperature you have your hot water set to and how many gallons of hot water the unit is currently having to supply. Another factor in many places is the temperature of the water coming into the unit and how many degrees it has to be raised. However, this mostly only matters in places with cold winters. It really doesn’t make much of a difference in Florida, since the temperature of our water supply rarely drops by that much.

Comparing Average Daily Energy Use for Tank and Tankless Water Heaters

It’s not really easy to say for sure whether an electric tank or an electric tankless water heater will use more energy per day. One reason is that tankless units are far more efficient, meaning they heat the water much faster. At the same time, it also requires far more electricity to heat water on demand. Despite typically using fewer kilowatts per hour, electric tank water heaters usually run for a few hours more per day. One reason is again just that they heat far more slowly. The other is that tank units suffer from an issue that’s commonly referred to as standby heat loss, which is when the water in the tank quickly starts cooling down soon after the unit shuts off. If the tank isn’t well insulated, this heat loss can sometimes lead to an additional hour or two of runtime per day or sometimes even more.

For an average home in Florida, an electric tankless water heater will typically use anywhere from 5 to 15 kWh per day since it doesn’t need to run for that many hours and typically operates at a fairly low capacity. An electric tank water heater will usually be on for a total of three to five hours per day. That means you’re looking at a total daily energy consumption of anywhere from 12 to 22.5 kWh. As such, a tankless water heater will often help you reduce your electricity bills by at least a bit compared to an electric tank unit. However, it really depends on the amount of hot water you use per day. For a household that frequently has a daily hot water demand of over 80 gallons, a tank unit may instead be the less expensive option.

One other factor that can have a major impact on the cost of running an electric tankless water heater is whether your electricity provider has peak or demand pricing. That means they charge higher rates per kWh at certain times of the day when electricity usage is highest. In this case, a tankless unit could cost you far more if you often use a lot of hot water during these peak demand times due to how much more electricity it uses compared to a tank unit.

How Much Energy Do Gas Tankless Water Heaters Use?

In truth, electric tankless water heaters often aren’t a great solution for meeting the hot water needs of an entire house, especially if the house is larger or has more people living in it. That’s again because of the extremely high energy demands. It’s also because you’ll often need to upgrade your electrical system with a higher-amp service panel in order to meet the water heater’s electricity needs. These reasons are why electric tankless water heaters are more commonly used as a point-of-use unit instead of a whole-home unit. A point-of-use tankless water heater just supplies hot water to a single room or fixture, such as the kitchen sink or the sink and shower in the bathroom.

If you want a whole-house tankless water heater, it’s almost always better to go with a gas unit. While gas units aren’t quite as energy efficient, the gas burner allows them to heat far more quickly and more effectively. That means the overall energy consumption is always far lower with a gas unit compared to an electric one. While comparing gas and electricity isn’t straightforward, the fact is that gas units consume far less energy overall and thus cost far less to operate. In fact, your water heater costs could potentially be 50% lower with a gas tankless unit. This is also because electricity rates are typically quite a bit higher compared to the cost of natural gas.

Buehler Air Conditioning & Plumbing is a locally-owned business that’s been serving Jacksonville and the rest of Duval County for the past 15 years. When you need a new water heater, you can count on us to provide high-quality work and affordable pricing. We offer a range of tank and tankless water heaters and can easily help you find a unit that fits your budget and will fully meet your hot water needs. We also offer plumbing installation and repairs as well as indoor air quality solutions. To see how we can help you, contact us today.

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