GSW Water Heaters

 For a residence, gas tankless water heaters, over electric, are the preferred choice as they can handle a larger temperature rise and still provide a strong output of hot water. Electric tankless water heaters in Canadian climates are only suited for point-of-use applications.

Tankless water heaters are becoming increasingly popular. As the demand for tankless installation increases, so does the demand for professional learning surrounding tankless water heaters.

This guide will help you understand the basics of how to properly size a tankless water heating unit for your customers’ homes. To learn more about tankless installation and get certified online, visit A.O. Smith Academy.

Typically, houses are sized so that, at a minimum, all showers can run simultaneously regardless of how many people live in the home. To properly size a tankless water heater for a home, there are a few key things you need to consider: ground water temperature, desired hot water temperature, temperature rise, and peak hot water usage. Below will cover how to determine these factors, and what the results of your analysis will mean.

Groundwater Temperature

Groundwater temperature is the temperature of incoming water into your home. Where you live will affect the average groundwater temperature. In Canada the average groundwater temperatures are between 35-42°F. This temperature will determine how hard your water heater has to work to heat your water to the desired temperature.

Desired Hot Water Temperature 

The desired hot water temperature is the temperature you set your water heater to. This temperature will be the temperature of your hot water when it is heated in your water heating unit. This temperature coupled with your groundwater temperature is how you will determine temperature rise.

Temperature Rise

When calculating temperature rise, you want to leave some room for error. For instance, because in Canada our average groundwater temperatures are between 35-42°F, you want to use the lowest temperature for your calculations. This will ensure that your water heater can keep up with demand no matter how harsh your cold seasons are. To determine temperature rise, you want to subtract your groundwater temperature from your desired hot water temperature.

120°F - 40°F = 80°F

In the example above, the temperature rise would be 80°F. After you calculate your temperature rise, you can then reference a flow rate chart from any tankless water heater brand to determine your maximum flow rate.

Peak Hot Water Use

With the calculated temperature rise, and referencing the Flow Rate vs. Temperature Rise chart, we can see that our maximum flow rate available would be 4.7 GPM.

The next step in sizing a tankless water heater would be to determine the maximum number of appliances that utilize hot water that could be running simultaneously, at any given time. Once that is determined, you will need to calculate the flow rate of every fixture and ensure that the total is less than or equal to 4.7 GPM.

If you find that one tankless unit is not going to suit your needs, you can Easy-Link up to four GSW condensing tankless water heaters with no additional parts or accessories required, made possible by the built-in Easy-Link-System.

To view all the features and benefits that come with GSW’s Power Direct Vent Condensing Tankless Water Heater visit our website.