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Hot Water Heaters: Does Size Matter?

Hot Water Heaters
Reading Time: 2 minutes

If you’ve ever been last in line to shower in a home with a water heater tank that’s too small then you’ll know how important it is to choose the right size water heater for your home. 

Too Small

If your water heater tank is too small, there will never be enough hot water for everyone. Apart from keeping the peace in your family, an over-worked water heater will be prone to breaking and will need regular repairs to keep it functioning.

Too Big

Always having enough hot water is wonderful, but a water heater that is too big will constantly be warming up water that doesn’t get used, running up energy bills that aren’t necessary.

Tank or Tankless?

There is another option in your search for the perfect amount of hot water – the tankless water heater. A tankless water heater uses built-in coils that heat water on demand. The upfront cost to install one of these is higher but this method of water heating is more efficient than storage tank heaters. Keep in mind though, they only provide about 3.5 gallons of hot water per minute. This makes them unsuitable for homes that tend to use hot water for more than one purpose at a time.

Storage Tank Water Heaters

These are the most common hot water solution, available for a lower upfront cost but less energy efficient. Storage tank heaters are much better suited to large families where hot water will be used for more than one task at a time.

How to Figure Out What Size Tank You Need

Here is a rough estimate using average numbers to give you a broad guideline.

  • 1 to 2 people: 30-40 gallons
  • 2 to 3 people: 40-50 gallons
  • 3 to 4 people: 50-60 gallons
  • 5+ people: 60-80 gallons

Each family has their own patterns and habits of hot water usage and the above is a suggestion that may or may not be accurate for your family. One major factor that will affect these numbers is how many hot water appliances your family will use at the same time in one hour. Families that run three or more will need a bigger tank, while a family who only uses one at a time, will need a much smaller tank.

Need A More Accurate Calculation? Take Out the Guesswork with This Simple Calculation 

  1. Pick the one hour per day that gives you your highest hot water usage. This is known as your ‘Peak Hour Demand’. Peak hour demand can also be described as the maximum gallons of water your family will need to get through the busiest shower-hour of the day. (Showers use the highest amount of hot water in the average home).
  3. Record all the info you collect onto this chart to add up the gallons of hot water you need during Peak Hour. 

  4. When you go to choose a water heater, track down the “first hour rating” (FHR) and choose one that as within 1-2 gallons of your peak hour demand. All water heaters have an FHR. This number states the number of gallons of hot water the unit can provide in a single hour, starting with a full tank of hot water.

If your FHR and peak hour demand match, your hot water needs will be met by the tank.

Too Complicated?  Call A Professional Plumber!

Save yourself time and let our qualified plumbers come in and work it out for you. They will advise you on the best water heater solution for your home.


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