Tankless Water Heaters -- How Much Hot Water Do You Need?

Are family members waiting in line to use the shower just to find out that there is no more hot water? Switch to a tankless water-heater system, and you and your loved ones will enjoy an unlimited flow of hot water and save as much as 33 percent on water-heating utilities.

How tankless systems work

A tankless water-heating system is installed directly to the plumbing. When you turn on a hot-water tap, cold water flows through a pipe heated on demand by an electric element or gas burner. Since there is no storage tank, like traditional water-heating systems, there is no wasted energy for standby heat loss or energy going toward continuous reheating of stored water. This is where tankless systems gain efficiency over traditional systems.

How much hot water does your family need?

An electric tankless system has a flow rate of about 2 gallons per minute (GPM), whereas, a gas system has a flow rate of 5 GPM. For smaller households that use less than 41 gallons per day, one tankless system should be adequate. However, if you have a larger household, and you use 80 gallons per day or more, you may need more than one system. For larger households, installing a tankless unit at each outlet is desirable for the greatest efficiency, which can reach as much as 50 percent over traditional storage-tank systems.

Your tankless water heater is sized, or rated, by the maximum temperature rise (groundwater temperature minus desired hot-water temperature) compared to your flow rate (GPM used). For example, if your incoming groundwater temperature averages 60 degrees, and your desired hot-water temperature is 125, your household’s temperature rise is 65 degrees. To measure your flow rate, determine the maximum outlets that are in use at any given time, such as for a shower, washing machine, and one sink. Then, add the flow rates for each outlet, and that will give your household’s flow rate. To ensure that your calculations are correct, you may want to consult with a heating and cooling professional.

Tankless water-heating systems are an efficient alternative to traditional systems, with greater energy savings and equipment longevity. Call Joe Behr Plumbing and Heating, and we will help you make the right choice for your family's needs. We've proudly served Mid-Ohio customers since 1965.

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