A tankless water heater is just that – a water heater without a tank. A tankless water heater works by heating your water on demand as it flows through the tank. When you turn on a faucet, it signals to the water heater that you are requesting hot water, fires up the burner, and begins to heat your water as it flows through the heat exchangers. This technique supplies you with an endless supply of hot water. Tankless units are much smaller, so they are great for small-space applications and are equipped to provide hot water for your entire family when sized correctly.
With this type of water heater, you don’t need to be concerned with the capacity of hot water it holds, because you will never run out of hot water. You do, however, need to think about flow rate.
Every tankless water heater has a maximum flow rate – the maximum amount of water it can heat and provide your home with, within a given time. Each fixture in your home that uses hot water has an average flow rate. These average flow rates should be referenced when you are deciding on a tankless water heater.
| Sink Faucet | Bathtub | Shower | Dishwasher | Washing Machine | |
| Average Flow Rate | 1 GPM | 3 GPM | 2.5 GPM | 3 GPM | 3 GPM |
Table 1.0: Average flow rates of household fixtures in gallons per minute (GPM)
If you look at the above table that suggests the average flow rates of your most used hot water fixtures it will give an idea of if a tankless water heater would be suitable for your home. Think about your average day – what fixtures do you run all at once? Add those together, and that will give you the flow rate your tankless would require to keep up with your family demand. You should size your home as if all of the showers in your home will be running at the same time, as a minimum.
The last environmental condition that you need to consider when thinking about a tankless unit is your climate. Your tankless water heater’s flow rate will depend on the temperature difference between your incoming ground water, and your desired hot water temperature – the bigger the difference between those two temperatures, the lower your flow rate will be. Here in Canada, we average about a 80°F temperature rise (40°F incoming water heated to 120°F).
In Canada, water heaters continue to be the second largest utility consumption in the home. While it is true that installation of a tankless water heater can be expensive, the peace of mind it will bring you is worth every penny. Tankless units themselves cost anywhere from $1,700 – $3,000. The installation of these tanks can also be a significant cost. Installations may require an upgraded gas line to accommodate the increased gas input, or additional venting accommodations to be made. You will also want to purchase an isolation valve kit (if one is not included with your system) to make maintenance much easier.
The installation and cost of a tankless water heater can be up to 3 times the amount of a tank-type water heater. With that being said, tankless water heaters are much more energy efficient. According to energy.gov, tankless water heaters can provide your home with potential energy savings anywhere from 8%-50% depending on your water usage and number of units installed.
Tankless water heaters have some of the best warranties on the market. They are constructed out of strong materials that allow them to last up to 15 years with the proper maintenance.
If you live in an area with hard water, it is important that you ensure your water is softened for your tankless water heater’s optimal performance. It is recommended that you flush out your tankless unit (like a tea kettle) every 6 months to a year to decrease the amount of lime and scale that builds up inside the unit. A local plumber can perform this task for about $120, or you can do it yourself.
As mentioned above, tankless water heaters offer better performance and a space saving design, but the most important thing to consider is your family’s water usage.
If you are still unsure if a tankless will meet your needs, try our product selector tool.
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