How the Capacity of a Water Heater is Measured and in What Unit

If you’re planning to install a water heating system for your home, you must know the correct size and capacity that will suit the size of your house. If you are new to water heaters, this tutorial would be fit for you to learn. It tackles the right measurement and installation of a water heater for homeowners like you.

You must be wondering; the capacity of the best electric hot water heater is measured in what way? You won’t have to worry anymore, we have provided a thorough tutorial for you to follow. Here’s everything that you should know about water heaters, their sizes, measurements, and how to pick the right one.

Knowing About Water Heater Capacity

In this tutorial, you will know of the following essentials:

  • The Capacity of Water Heater Tanks
  • Horizontal Cylinder Water Tanks
  • Vertical Cylinder Water Tanks
  • The Capacity of a Water Heater Is Measured in What Unit?
  • How to Identify the Capacity of a Water Heater
  • Things to Consider Before Deciding Your Water Heater’s Size

The Capacity of Water Heater Tanks


First, let’s talk about the capacity of water tanks and how you can measure them. We have provided a step-by-step process to guide you on every type of water heater tanks:

Horizontal Cylinder Water Tanks

  1. Measure the circle’s radius at the lowest of the cylinder. A radius is any line section that runs from a circle’s middle to its perimeter. To locate the scope, measure from the mid-factor of the cylinder’s backside to the outdoor of the ring. For any circle, the diameter is measured as twice the radius.
  2. Find the area of the circle at the bottom of the cylinder. As soon as you understand the radius of your backside base surface (B), you could calculate the vicinity. To accomplish that, use the method B = πr2, using your radius as r and 3.14159 for π.
  3. Calculate the full extent of a cylinder tank. You could now determine the total quantity of the tank using multiplying the vicinity by way of the length of the container. The overall formula for the full extent of the tank is Vtank = πr2h.
  4. Become aware of around region and phase. If you believe a circle reduces into slices, like a pizza, each slice is a sector. If a chord cuts via that quarter, it divides the world into two components: a triangle and a base.

This section is vital because to calculate the stuffed quantity of your cylinder; you’ll have to discover the region of a segment and multiply it through the duration of the cylinder.

  1. Decide the region of your area. The arena is a fractional portion of the region of the complete circle.
  2. Get the area of the triangle. Find the location of the triangle that becomes fashioned through the chord that cut via the sector.
  3. Subtract the location of the triangle from the position of the area.
  4. Multiply the area of your segment through the height of your cylinder.
  5. Determine the filled top. Your very last step relies upon on if the height, d, is extra than or less than the radius, r. If the peak is less than the radius, use the volume created from the crammed Vfill.

So, If the height is higher than the range, use the amount created through the hollow portion, minus the overall volume of the tank.

Vertical Cylinder Water Tanks

  1. Find the place of the circle at the lowest of the cylinder. Once you already know the radius of your backside base floor (B), you may calculate the vicinity. To achieve this, use the method B = πr2, the use of your radius as r and 3.14159 for π, which is a mathematical constant.
  2. Calculate the full quantity of a cylinder tank. You can determine the overall amount of the tank by multiplying the vicinity by the duration of the container. The whole system for the total extent of the tank is Vtank = πr2h.
  3. Determine the filled extent. The stuffed volume is just a shorter cylinder with the same radius but a distinctive top: the filled top, d. Therefore:

What is the Capacity of a Water Heater Is Measured and in What Unit?

The capacity of a water heater is measured in two approaches. For example, within the United States, they use “gallons” in sizing their water heater. Meanwhile, countries which can be utilizing the imperial system or the British Imperial have their water heaters measured in liters.

Both forms of measurements are accurate. You may even have the liberty to convert the devices to your chosen measuring gadget. There are a variety of conversion calculators sprawling at the internet these days that you may use for conversion.

There’s no need anymore to damage your mind if you are not adequate at doing arithmetic.

How to Identify the Capacity of a Water Heater

You can usually take a look at the labels affixed to the water heater. Somewhere there, you could find the figures that you are searching out within the process.

In case you need to recognize the specifications of the water heater, see its guide. Producers can also have indexed everything there; from the energy necessities, right down to the repair techniques.

Things to Consider Before Deciding Your Water Heater’s Size

  • How Much Water Does Your Family Use?

Don’t forget the number of your family members. The usual families make use of 20-30 gallons of warm water each day. First-hour rating helps to decide how the unit will perform in the course of a hectic period.

Look at the whole BTU load of all the home equipment in your private home that would be running at the equal time. You can use GPM (gallons per minute) to track how many gallons of water can be filled in keeping with the minutes. The less water used according to a minute, the higher the water temperature can be.

  • How Would the Water Heat Up?

This can depend upon what you already have. If you are not satisfied along with your present-day heating method, you’ll need to bear in mind the budgeting options for changing to a brand new one.

  • How Much Space Do You Have?

A standard size water heater is 40 gallons. Otherwise, you have to make sure that the size you’ll purchase will fit the allotted space. It’s also a better choice if you choose the size that can leave an extra space once installed.

Options for smaller spaces: small or tall heaters, based on how space is constrained.

  • How Much Energy Would You Like to Save?

Actively thinking about how efficient a unit you want is a crucial part of this choice. Because there may be going to be a more significant upfront value, you do need to decide how much energy you want to collect. The savings will not be immediate. However, it will make a distinction over time.


In summary, how is the capacity of a water heater measured and in what unit? It is called gallons. There are also several crucial factors for you to consider before purchasing a water heater. If you want to have the correct heater size and capacity for your home, take note of these essentials.

So, now that you’ve read the guide have you come up with the decision? What size of water heater would you get? Let us know your answer in the comments and their reasons. We hope that this tutorial was a great help to you!



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