The Beginner's Guide to Tankless Water Heaters and Sizes

Daniel Paul
January 13, 2022

So, you're thinking of getting a tankless water heater. It's a reasonable desire, considering the fact that they are more energy-efficient and can lead to better savings in the long run.

Of course, it's best to figure out their pros, cons, and how to figure out the right size for your space before you get one.

How to Pick Your Tankless Water Heater's Size

  1. The first thing you need to do is figure out how many devices you intend to use with the heater. Then, you should get their total flow rates.
  1. Now, check the temperature rise to see what you need. In order to get this calculation, you just need to know the desired temperature output and subtract the actual water temperature incoming. If you don't know the incoming temps, then it's best to go on the lower temps, so you don't end up underestimating.
  1. Finally, measure the water usage from your bathrooms. In particular, you should look at the shower and make sure you have enough hot water for twice the consumption. This will take into account simultaneous usage.

Once you've got that all figured out, you will have a computation of the necessary temperature and gallons of water for your lifestyle. From there, you can check the specifications of various tankless water heaters to see what matches your needs.

Pros and Cons to Going Tankless

A few key advantages to consider are:

  • A tankless water heater can save money in the long run. Your savings will come in the form of reduced energy costs. However, you do have to be aware of the long-term maintenance costs as you go through the years.
  • You no longer have to wait so long just to get your hot water. Tankless heaters can produce continuous hot water almost instantly.
  • These heaters are built to last longer, so you don't have to worry about having to get a replacement with just a few years of use. They can last at least twice as much as traditional tanked models, with gas heaters living up to twenty years or more.
  • They are more efficient, making things more convenient for the homeowner but also ensuring that environmental impact is lessened.

Of course, there are some cons to keep in mind as well:

  • The initial cost is significantly higher than a tanked water heater. Not only do the tankless models cost more, but they also require some labour for installation.
  • Even though tankless models supply a great stream of hot water, they don't have a limitless supply. This is what makes it crucial to calculate how much you need, as they will have specifications of how many gallons they can handle (that are often less than traditional heaters).


Now that you've got these figured out, the process should be smoother for you. Make sure you note the differences between gas and electric heaters, too. If you're still not sure how to go about it, you can reach out to professional plumbing services so they can do the inspection and figure out the best size for your place.

For homeowners that want a tankless water heater in Calgary, contact Northern Oasis Plumbing. Get in touch with us to learn more and get your installation started.