Water Heater Sizes: A Guide

A water heater is an essential investment for any home. That being said, it's important to make sure you buy one that’s correctly sized in order to meet your family’s needs. Otherwise, you may be left without warm water for your morning shower more often than you'd like.

Water heater sizes: a guide

Today we'll explain the difference between the two main types of water heaters to help you choose the right one for your demands. We'll also provide you with an overview of popular water heater sizes and how to choose the best one for you.

Storage Tank or Tankless? Types of Water Heaters

There are two primary types of water heaters: storage tank water heaters and tankless water heaters.

Tankless water heaters

A tankless water heater, albeit more expensive upfront, will provide you with hot water no matter what.

Tankless water heaters work by using built-in coils to heat water when you need it, meaning you’ll always have hot water on demand. This makes these types of water heaters more efficient than traditional storage tank water heaters. The only catch? They provide a limited amount of hot water per minute — on average, about 3.5 gallons per minute. For this reason, these types of water heaters are ideal for households that plan on using water for only one task at a time.

  • More energy efficient.
  • Hot water on demand.
  • Offer a limited amount of hot water per minute.
  • Not ideal for large families.
  • High upfront cost.

Storage tank water heaters

Storage tank water heaters are far more common than tankless water heaters. This type of water heater features an insulated tank that stores hot water until it’s needed.

We’ve all experienced the woes of running out of hot water, or waiting for water to heat up before jumping in the shower. These types of things happen because storage tank water heaters have what’s called a recovery rise, or the amount of water they can heat in an hour. The more you depend on hot water in your home, the higher the recovery rise you’ll need.

  • Low upfront cost
  • Suitable for large households
  • Limited amount of hot water in a given period of time
  • Not as energy efficient

What Size Water Heater Do I Need?

To narrow down your search for the perfect water heater, you'll want to keep in mind a few key factors:

  • Your fuel source - Will you use natural gas, liquid propane or electricity for fuel? Or, will your water heater connect to your boiler? Determining this first will help you narrow down your options and make the shopping process much easier.
  • Physical size - Make sure you find a water heater that will fit in the designated space in your home.
  • Household size - Do you have a small condo or a large house? Is it just you and your partner, or do you have a big family? The size and occupancy of your household are some of the most important factors to consider when water heater shopping.

You’ll most likely need a higher capacity water heater to accommodate a household where multiple people shower, wash dishes and do laundry at the same time, compared to a small condo where you just need hot water for one task at a time.

Water Heater Sizes

Storage tank water heaters Storage tank hot water heaters are sized based on BTU input and capacity in gallons. Again, the more you rely on hot water on a regular basis, the more BTUs and capacity you’ll need.

Here’s a rough guide for storage tank water heaters:

  • If your family size is between 1 and 2, you’ll need a water tank with at least a 30-gallon capacity.
  • If your family size is between 2 and 3, you’ll need at least a 40-gallon capacity tank.
  • If your family size is between 3 and 4, you’ll need at least a 50-gallon capacity tank (electric) or a 40-gallon capacity tank (natural gas or liquid propane).
  • If your family size is 5 or more, you’ll need an 80-gallon tank (electric) or a 50-gallon tank (natural gas or liquid propane).

Tankless water heaters If you’re interested in going the tankless route, your shopping journey is a little bit different. Since tankless water heaters don’t store water, you don’t have to worry about capacity size. However, you still need to be mindful of two factors: Flow rate and temperature rise. To determine the water heater flow rate needed, you'll want to add up the flow rates of all the appliances you plan to use at the same time (showers, washing machines, etc.). You'll then determine the necessary temperature rise by subtracting the incoming temperature from the desired outgoing water temperature. If you're not sure, you can use 50 degrees Fahrenheit as the incoming temperature and 100 degrees Fahrenheit as the desired outgoing temperature. In this case, you would want a tankless water heater with a temperature rise of 50 degrees.

Buying Your Water Heater

We hope this guide has helped clarify the different factors you should consider before purchasing a water heater. At Total Home Supply, we carry an assortment of both storage tank and tankless water heaters, all available with free shipping to anywhere in the contiguous United States. If you need additional assistance before making your purchase, contact us. Our in-house experts will be happy to help you find the right water heater for your specific needs.