Choosing the Perfect Tankless Water Heater Size for Your Needs

what size tankless water heater

“What size tankless water heater do I need?” is a common question for homeowners planning to go tankless. Tankless water heaters are a relatively new technology, and without a bit of prior knowledge, it can be tough to tell which one will work best for your home. 

The experts at Tampa Bay Plumbers can help you size a tankless water heater and get your new water heater installed, but you can also use this guide to get a good head start. 

Figure Out Your Flow Rate

The best way to start figuring out what size water heater you need is to determine the flow rate required to support all of your hot-water appliances. 

If a single tankless water heater can’t support the flow rate you need, you can divide that rate between multiple models as well. Keep in mind that gas tankless water heaters and electric tankless water heaters support different flow rates. 

Your flow rate also doesn’t need to be high enough to support every appliance at once, especially if you live alone or have a small family. Instead, plan for typical use, potentially with a small buffer for high-usage times. Of course, you can always install low-flow fixtures to give yourself more wiggle room down the road. 

Determine Your Temperature Rise

As you may have guessed from the name, temperature rise refers to the difference between the incoming temperature of your water and your desired outgoing temperature. 

Tankless water heaters are also known as “on-demand water heaters,” meaning they heat water for you as needed. That means that your system needs to be able to heat the correct volume of water to the correct temperature whenever you need it. 

You should aim to reach a maximum temperature of 100° – 120° from your entire hot water system, but you can shoot for a lower or higher temperature if you prefer. Next, you’ll need to take the incoming temperature of your water into account. Here in Florida, your incoming water temperature might sit consistently around 60° – 70°. 

Ideally, you should aim to create a hot water system that can handle the maximum temperature rise you might need, and then some. For example, if your water comes in at a minimum temperature of 60° during the winter, you should plan to install a system that can heat the water to about a 50° temperature rise. 

In the end, the answer to “what size tankless water heater do I need?” is this: you need a water heater that can handle both your desired flow rate and your desired temperature rise at the same time. If you need help choosing a water heater or tankless water heater installation services in Tampa, call Tampa Bay Plumbers at 813-758-6237 today.

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