What size water heater do I need?
Sized by your busiest hour of hot water use, which is how tank heaters are rated.
First hour rating needed
73 gal
Typical tank size65 gal
Or tankless flow5.0 GPM
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How to measure
Think about your busiest hour of hot water use: showers, laundry, and dishwasher.
Tips from the field
- Compare the first hour rating on the yellow label, not just the tank size.
- Tankless heaters lose flow in winter when incoming water is colder.
What you'll need
Tank water heaterTankless water heaterExpansion tankWater heater pan
Common questions
What is first hour rating?
How many gallons of hot water a tank heater delivers in its first hour of use. It's on the yellow label.
What size water heater for a family of four?
Usually a 50 gallon tank, or a tankless heater around 5 to 6 GPM.
Is tankless better?
Tankless saves energy and never runs out, but costs more upfront and loses flow in cold weather.
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Printed from housecalcs.com/tools/water-heater-size-calculator