What Size Tankless Water Heater Do I Need?

According to the family and house size, you need a tankless water heater that best suits all purposes and can deliver hot water instantly without waiting anymore.

What Does a Tankless Water Heater Mean?

A tankless water heater heats the Water directly and does not hold any tank to pre-storage hot Water. The tankless heater works on the spot when you turn on the tap, and the heating process will begin, and you will instantly get warm Water anywhere you want. It would be best to have a tankless water heater according to flow rates capacity for different purposes like shower, bath, sink, and dishwasher.

However, we discuss What Size Tankless Water Heater Do I Need? A point of use water heater can deliver hot Water only to that point where you want.  But for this, you need to determine tankless water heater size for multiple fixtures.  If you have a large family, you have to choose a 4-5 points-of-use water heater, and for a small family, 2-3 points-of-use of a tankless water heater is enough.

Tankless water heaters offer endless warm Water on demand. And has an above 20 years warranty. They are space-saving, and strong contractions make them durable and reliable.

If you are confused about which size is best suitable for a tankless water heater for your home, This buying guide helps you select the best-sized tankless water heater. In fact, it is the essential part of choosing a new unit for your home.

How To Determine Size Of A Tankless Water Heater?

Due to no storage unit, you have to consider the flow rates of the water heater and how much a tankless size best matches your requirements. You also must know How much Water can be heated if you turn on the multiple taps.

What is GPM?

GPM gallon per minute means how warm Water a tankless unit provides in a minute—for example, 2 GPM, 4gmp, 8gmp.

However, you have to consider the GPM per gallon per minute that a tankless water heater produces for measuring hot water flow rates. It doesn’t matter which type of source you use, either electric or propane. All kinds of water heater performance will be the same, just the heating function varies.

Size Of Tankless Water Heater

There are three factors you must consider before buying a tankless water heater.

House Size

First, you should determine how much warm water you need in your house. If you have a small place and want 2 -3 hot water points of use required, go with a regular size tankless water heater. But if you have a large family and want multiple points of use, water heaters. For example, school, college, commercial use, or for a double, triple floor house.

Flow Rate (GPM):

The Flow Rates mean How much hot Water flows at a time? Suppose you need two hot water taps of shower runs simultaneously and a sink tap. So, the suggestion of 2.5 gallons per minute flow rates is best suitable for this. And fulfill hot water demand instantly. If you need to run more fixtures, see the table below and find which warm-water flow rates best suit you according to your needs.

Measuring Table

TapsGPMTemperature
Tub4-GPM102F
Dishwasher1.5-GMP110F
Shower 2.5-GMP104F
Sink1.5-GMP110F

So, now you can easily find the solution of which tankless size is better for you. Remember that a tankless never stores hot Water; it only heats when you turn on the tap.

Overall, These flow rates are sufficient for all purposes. You can select a water heater and set temperature modes according to the usage.

Temperature Rise

Next, in this term, we have to consider groundwater temperature and heating water temperature differences. That helps to find the best tankless water heater with excellent heating elements that heat the water quickly. Suppose you live in a cold place where the groundwater temperature is shallow, then you need quick and high-temperature rise heaters that quickly heat the cold water.

Typically every faucet has normal temperature modes like 110° F – 120° and the Groundwater temperatures average 57° F in the U.S and other cold areas 70° F.

Sizing Example:

For an average shower, 2.5-3 GPM can hold 104–106°. And for two showers with ground temp 40 degrees, you will use above 5 GMP, and heats will be 60-degree temps.