HouseChalk
Tank water heater
A tank water heater stores and continuously heats a reservoir of hot water, typically 40 to 80 gallons, for immediate use.
Why it matters
It delivers hot water at high flow rates but runs out during heavy use. The first-hour rating tells you how much hot water is available before recovery is needed.
Where people get this wrong
A tank heater keeps water hot 24/7, which uses standby energy. A tankless heater only heats water when a fixture is opened.
Real-world example
Your 50-gallon tank water heater has a first-hour rating of 67 gallons, meaning it can deliver 67 gallons of hot water before you notice a drop in temperature.
Where this hits your build
This comes up during rough-in and final fixture installation. Accessibility for future repairs matters as much as the initial install.
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