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Tankless 101: How do I know which one is best for my home?

Section 1: What is a tankless water heater?

Section 2: Why should I care?

Section 3: When should I consider using one?

Section 4: How do I know which one is best for my home?

We speak to hundreds of customers every day and the question that comes up most often is "What tankless water heater is the right one for my home?" It's a legitimate question! Probably the most important question to be honest.

So what criteria do we use to properly size a tankless water heater for you? Well, here are the questions we ask of everyone who calls for help with sizing.

  1. What is the incoming water temperature where you will use your new tankless water heater?

  • The most important factor in determining what size heater you will need is where will it be located geographically. Where the heater will be installed is very important because of the incoming water temperature in the area.  For example, the incoming water temperature in Miami is an average of 80 degrees whereas the incoming water temperature in northern Maine is 40 degrees.
  • A tankless water heater is capable of producing hot water based on a temperature differential or what is also know as DELTA T (ΔT). Let's take a closer look at the Miami/Maine example referenced above: A tankless heater with a ΔT of 40° at 2 gallons per minute will produce 120° water in Miami whereas the same exact heater will only produce 80° water in northern Maine. This is because tankless water heaters do not technically heat water "to" a specific temperature but "by" a specific temperature. That said, it is possible to achieve a specific temperature output, and more importantly, maintain it, if your heater is properly sized for your geographic area, use and application.


    Don't know your incoming water temperature? Here's a map to help.
    Color coded map of the United States showing average incoming water temperature.


  • How many bathrooms do you have?

    • It is important to know how many bathrooms you have in your home but more important is to know how many bathrooms you use at the same time. In other words, if you live alone in a three bathroom home and only one bathroom is ever used then technically you have one bathroom. On the other hand if you constantly have house guests or if you have a three bedroom home with five people living in it, then the equation changes a bit.

    • We like to size the heater for the home not the users. Essentially, it is important that you consider a few "forward-looking" factors when answering this question. If you choose a heater that suits your personal usage but not your home size, you will undoubtedly run into issues if you ever decide to sell. We also like to be flexible so we consider the big picture as well. This means that if you are only trying to heat water to one bathroom even if you have 10 of them, we'll consider that when sizing your heater.

    • The reason why we ask how many bathrooms you have is essentially in an attempt to gauge how many gallons per minute you will require when using your heater. Gallons per minute or GPM is one of the most important factors when sizing your heater. GPM coupled with required temperature differential allows us to make a calculation for necessary kilowatts.

    • We are in the process of finalizing this page.. Please check back soon. In the mean time, please check out our sizing guide here. Or, try giving us a call, there is always someone available to answer the phone 1-305-823-6991