What is a good first hour rating for a water heater?
The first hour rating every storage model on file actually lists, by tank size, next to the DOE method for checking it against your own household.
First hour rating, the gallons of hot water available in the first hour from a full tank. No single number is good: DOE's method is to match it to your household's busiest hour. Across the 1,525 storage models on file that list one, the median runs from 51 gallons at a 30-gallon tank to 90 at 75 gallons.
What models actually list, by tank size
Storage models only; tank sizes within 5 gallons of each nominal size, the same bands the sizing questions use, so a tank on a boundary appears in both.
| Tank size | Models | Lowest | Median | Highest |
|---|---|---|---|---|
| 30 gal | 285 | 34 | 51 | 165 |
| 40 gal | 593 | 38 | 64 | 91 |
| 50 gal | 572 | 41 | 77 | 119 |
| 65 gal | 64 | 76 | 80 | 100 |
| 75 gal | 72 | 83 | 90 | 101 |
What it measures
First Hour Rating: how many gallons of hot water the unit can deliver in one hour, starting from a full tank.
Storage products only. Tankless units are rated on max GPM instead, and an empty FHR there is a product-class property, not missing data.
Check it against your household
Each question below applies DOE's peak-hour method to the models filed at that size.
Related pages
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Find what replaces your water heater
Enter the model number off your old unit and see what is on file today, with the yearly cost difference.
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Find a water heater that fits
Three questions — fuel, hot water need, install space — narrow every model on file to the ones that fit.
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What a water heater costs to run
Prices a unit's efficiency against your own utility's filed tariff for your ZIP code.
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Water heaters
Every model on file with the Department of Energy, by heater type.
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How the numbers are calculated
The formula, the tariff rule and where published costs disagree.
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