Construction
Tankless Water Heater Sizing Calculator
Tankless heaters need enough GPM at the right temperature rise. Climate zone is the biggest variable.
Required GPM
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- Temp rise
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- BTU/hr (gas)
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- kW (electric)
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FAQ
Why does inlet temp matter so much? +
A 40F well in Minnesota needs nearly twice the BTU to reach 120F as a 70F inlet in Florida. Climate is everything.
Gas vs electric tankless? +
Whole-house electric needs 100-200A service. Gas (180,000+ BTU/hr) is the realistic option for most homes.