Water HeaterHow to Size a Tankless Water Heater

Tankless water heaters are small in size and because they heat on demand, it may seem that sizing is not an issue. The truth is, a tankless water heater does have to sized for your home in order to provide you with the hot water you need, but the sizing calculation is handled differently than that of a storage tank water heater. Working with a trained expert, like the ones from G&S Heating, Cooling & Electrical, Inc., can help you determine what size tankless water heater you’ll need for your Bellevue home.

Water Temperature Is the Key

With a heat-on-demand system, the goal is to make sure your hot water is heated to the temperature you want; tank water heaters don’t have this issue because the water held in the tank is already heated. The first temperature to consider in the configuration is the temperature you want your hot water to be; most people keep this number to a maximum of 120 degrees. The next temperature to look at is your ground water temperature, and for that, you’ll have to take into account where you live. In our area, the average water temperature is around 50 degrees. So to achieve a hot water temperature of 120 degrees, your tankless hot water heater has to heat the water an extra 70 degrees. This is known as temperature rise.

Flow Rate

The next factor in the calculation is flow rate. Flow rate in a tankless hot water heater tells you the maximum gallons of hot water that can demand hot water at any time. Flow rate is calculated in gallons per minute (GPM) and every faucet, showerhead and spigot in your home has a flow rate in GPM. Your technician will have a standardized chart detailing the average flow rates for the various water-using appliances you may have, and add up your average hot water flow rate. Then, using the temperature rise and your daily GPM, he/she will be able to tell you what size tankless water heater will be best for your home, in GPM.

Taking the time to correctly calculate the size you need for your tankless water heater in Bellevue ensures that you’ll have all the hot water you need.

Need help? Call G&S Heating, Cooling & Electrical, Inc., today and make an appointment with one of our installation specialists.


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