What Size Tankless Water Heater Do You Need? Sizing for San Clemente Homes From the Pier Bowl to Talega
Tankless sizing is about flow and temperature rise, not tank gallons. How to count fixtures, what San Clemente incoming water temperature means and how pipe size…
Switching from a tank to a tankless water heater changes how you think about size. Instead of gallons stored, you size by how many gallons per minute you need at once and how much the water has to be heated. San Clemente homes range from compact 1920s and 1950s cottages near the Pier Bowl to large Talega and Forster Ranch houses from the 2000s, so the right unit varies widely.
The two numbers that matter
- Flow rate: the total gallons per minute of hot water you expect to use at the same time.
- Temperature rise: the difference between incoming water temperature and the hot water setting.
Manufacturers publish charts showing how much flow each model delivers at a given temperature rise. San Clemente's mild climate helps, because incoming water rarely gets as cold as it does inland, so a unit delivers more flow here than the same model would in a colder region.
Counting fixtures
Think about your busiest moment, often a weekday morning. Typical flows are roughly:
- Shower: about 1.5 to 2.5 gallons per minute with modern heads.
- Bathroom sink: around 1 gallon per minute or less.
- Kitchen sink: around 1.5 gallons per minute.
- Dishwasher and washer: varies by model and cycle.
Add up the fixtures likely to run together. Two showers and a kitchen sink at once may call for 5 to 6 gallons per minute. Large homes with body sprays, soaking tubs or more simultaneous use may need a larger unit or two units working together.
Pipe and gas size matter too
A properly sized heater still needs adequate water supply and, for gas models, adequate gas line capacity and correct venting. Many older San Clemente homes have undersized gas lines or water lines that were fine for a tank but restrict a high-output tankless unit. When we plan an install, we check the water supply size and coordinate the gas and venting requirements with the right trade so the unit performs as rated.
Coastal considerations
Salt air near the beach is hard on exterior equipment. An outdoor unit should be rated for the location, and an interior install needs proper combustion air and venting. Water service from the City of San Clemente utility has moderate hardness, so isolation valves for future flushing are a must.
Permits
Water heater replacement requires a permit through the City of San Clemente. If you are repiping at the same time, the water heater connections can be updated as part of the same project.
Related reading
Plan the rest of your system with our guide on how long PEX lasts, and see what a tankless water heater installation involves. Homeowners nearby can visit Dana Point, San Juan Capistrano and Ladera Ranch, or see the full service map at repipeinc.com.
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Repipe OC, 23821 Hillhurst Drive, Laguna Niguel, CA 92677, (949) 524-2362, CSLB #1087885 C-36.
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Written by Repipe OC · CSLB #1087885 C-36 · 23821 Hillhurst Drive, Laguna Niguel, CA 92677 · (949) 524-2362