Getting the proper sized heater requires a Goldilocks equation. If you get one that’s too small, you risk running out of hot water in the middle of a shower. If you get one that’s too big, on the other hand, you’re wasting valuable money heating water that you’re not using.

So how to do find the “just right” heater? Take a look at its first hour rating.

Understanding First Hour Rating

To properly assess what size of water heater you need, it’s important to look at the unit’s first hour rating (FHR), which is the amount of hot water that a heater can continuously provide per hour before the tank runs empty.

Here’s another way of looking at it: How long can your heater provide hot water during a busy hour of the day, such as in the morning when your entire family gets ready for work or school.

There are several factors that affect the FHR, including the heating source (oil/gas/electric), how big the heating source is, and the size of your tank. This rating is often indicated on the heater itself, allowing you to easily determine if the size/capacity is right for your home.

That being said, how do you determine the FHR of your home so that you can buy a product that meets it? As HGTV recommends, first assume that each family member will use 12 gallons of hot water during peak times of the day. This includes all activities that might involve using hot water: showers, washing the dishes, shaving, washing hands, doing the laundry, and so on.

Next, estimate the maximum occupancy of your home by counting the number of bedrooms plus one. Then, multiply the maximum occupancy by 12 to get your minimum FHR.

So, if your home has three bedrooms, your maximum occupancy will be four (three plus one). If you multiply 4 by 12, your water heater storage rating equates to an FHR of 48 to continuously supply your family with hot water during peak usage hours. However, says that you can buy a unit within 1-2 gallons of the ideal FHR—after all, the formula already incorporates a buffer.

Thanks to the first-hour rating or FHR, it is easy to determine just how big of a tank heater your home needs. Now that you know how big your heater should be, it’s time to look for water heaters from trusted plumbers in Saskatoon. They can recommend the best models for your home and also install the unit for you.


Sizing a New Water Heater,

Choose the Right Size Water Heater,