Installing a tankless water heater (or on-demand water heater) in many homes is a good decision that will reduce energy use and utility costs while providing your household with an unlimited source of hot water. That is if the system is sized properly. Proper sizing of each tankless unit is critical for effective operation and can be determined by calculating the hot water needs in your home.
Tankless water heaters are rated based on their maximum ability to raise water temperature at a particular flow rate. Whole house and point-of-use tankless water heater units are available. In the case of a whole house heater, you will first need to determine which devices may be using hot water at any one time (such as a kitchen faucet, washing machine and a bathroom shower head), then add up the flow rates of each device to obtain your desired hot water flow rate per minute. If your faucet uses 1/2 gallon per minute (gpm) and your shower head uses 3 gpm, your desired hot water flow rate is 3 1/2 gpm.
Once you know how much flow you need, choosing a hot water temperature for your whole house (or remote location in the case of point-of-use tankless water heaters) is the next step in sizing your new system. 120 degrees is recommended for most homes to prevent scalding and minimize energy use. In homes where hotter water is needed, such as for a dishwasher without an internal heater, 140 degrees should be sufficient.
Finally, the necessary temperature rise is calculated by subtracting the temperature of the incoming cold water from the desired hot water temperature. In a home with incoming water of 50 degrees and a water heater set to 120 degrees, the temperature rise needed would be 70 degrees.
With your desired temperature rise and calculated hot water flow rate, you can choose an appropriately sized tankless water heater for your entire home, and if necessary, choose one or more point-of-use tankless units to supplement the main tankless heater.
If you would like to learn more about tankless water heaters, please contact us at Energy 1 Heating & Air Conditioning; our friendly staff has been serving Lorain, Erie and Cuyahoga county homeowners for more than 50 years.
Our goal is to help educate our customers in Lorain, Ohio about energy and home comfort issues (specific to HVAC systems). For more information about tankless water heaters and other HVAC topics, download our free Home Comfort Resource guide.
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Energy 1 Heating & Air Conditioning
1 (440) 246-5440
Serving the Lorain, OH Area