Water Heater Terms to Know

First-Hour Rating (FHR) – measures how much hot water will be available during the busiest hour of the day. A large tank does not necessarily translate to a higher FHR.

Recovery Rating -- Indicates the water heater’s ability to replenish hot water as it’s drawn from the tank.

Efficiency – described as an Energy Factor (EF), which is usually listed beside the Energy Guide label. The higher the number the more energy efficient the water heater.

Frequently Asked Questions

Why don’t you offer rebates for tankless/on-demand water heaters?
The majority of tankless water heater use occurs at peak use times, i.e., prior to and after the daily work commute. Wide use of tankless/on-demand water heaters may strain electric power grids while they’re handling the biggest loads of the day.

Should I use a timer on my hot water heater to save energy?
A timer on a conventional electric water heater can save 5-12% on your hot water bill. The water in the tank remains hot for up to eight hours or more while the water heater is not in operation, depending on the insulation and age of the unit. However, the hot water is still available for household use until it is completely consumed. For example, if a household has a fifty-gallon water heater, it will have fifty-gallons of hot water available while the water heater is not in operation. Most households won't notice the interruption unless they have high hot water use patterns in relation to tank size. It is best to set the timer during hours when hot water use is lowest, typically during the work day or at night. Adjusting the timer may be necessary if households experience a shortage of hot water.

Comparison of Water Heaters
High Efficiency Water Heater Type Energy Savings vs Minimum Standards Best Climates Expected Energy Savings Over Equipment Lifetime Expected Lifetime Major Advantages
High Efficiency Storage (Tank, Oil, Gas, Elec.) 10%-20% Any Up to $500 8-10 years Lowest first cost
Demand (Tankless) Using Gas or Elec 45%-60% Any Up to $1,800 20 years Unlimited supply of hot water
Heat Pump 65% (Compared to electric resistance) Mild-Hot Up to $900 10 years Most efficient electric fuel option
Solar with Electric Back-up 70%-90% Mild-Hot Up to $2,200 20 years Largest energy savings using a renewable energy source

Source Material:US Dept. of Energy

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