How to Calculate the Size of a Tankless Water Heater

As their name suggests, tankless water heaters don't have a tank. Therefore, calculating the right size for a household is slightly trickier than with tank water heaters. A smaller tankless water heater might be more affordable, but it may not handle your household's water usage. On the other hand, larger water heaters could be an unnecessary expense.

We'll explain how to calculate the correct size of a tankless water heater for your home.

Step one: determine the number of devices and their flow rates

First, it's necessary to calculate the maximum number of devices that will use the water heater. Then, you need to determine their flow rate and add the numbers together. This is the speed at which water passes through a device, and it's measured in gallons per minute.

One of the ways to measure a device's flow rate is to take a bucket and see how long it takes to fill up. For example, if a showerhead fills up a five-gallon bucket in two and a half minutes, its flow rate is two gallons per minute. You can also check most devices' flow rates on the internet.

Step two: determine the temperature rise

The second step is determining the temperature rise (or the water heater's temperature) that the unit needs to deliver. By subtracting the incoming water temperature from the desired water temperature, you can get this number.

For example, if the incoming water temperature is 50 degrees Fahrenheit and the desired temperature is 110 degrees, the ideal water heater for that household should produce a 60-degree temperature rise.

Various online tools can help you determine the correct incoming water temperature depending on your area of residence.

Step three: calculate the size

Take the values from the previous two steps and determine the right size of a tankless water heater. Don't forget to pay attention to the number of devices that will use the hot water from the heater.

Also, focus on your peak-hour water demand. This is the time when a household spends the largest amount of water. A good water heater should cover the peak-hour water usage with ease.

Let the experts help

Since tankless water heaters don't feature a tank, they are an excellent storage-saving option for all homes. Moreover, they are energy-efficient because they don't constantly keep the water warm (unlike tank water heaters).

If you need help determining the correct size of a tankless water heater for the household, don't hesitate to reach out to professionals. They can do the necessary calculations and recommend the right size. Plus, they can offer valuable maintenance tips.

Before hiring a company, ensure they are trustworthy. Look for online reviews or ask for recommendations from family, friends, or neighbors. The right company should have years of experience and many happy clients.

Water Wise Plumbing is a local, full-service residential plumbing company serving Las Vegas, Henderson, Paradise, Boulder City, Pahrump, and North Las Vegas. We provide Tankless water heater service, water softeners, water heater flush, leak detection and repair, water line rerouting, pipe installation, hydro-jetting, sewer services, and more. We are family-owned and operated, certified, and insured. We offer flat rate pricing and 24-hour emergency service.Call us today at 702-597-9554.