First Hour Rating: What It Is, How It Works, and Why It Matters
What is First Hour Rating?
The first hour rating (FHR) of a water heater is the amount of hot water that the water heater can deliver in the first hour of operation. It is measured in gallons per hour (gph). The FHR is important because it determines how quickly the water heater can meet the hot water demands of a household.
How First Hour Rating Works
The FHR of a water heater is determined by the size of the water heater’s tank and the heating element’s wattage. A larger tank will hold more hot water, and a higher wattage heating element will heat the water faster.
When the water heater is turned on, the heating element begins to heat the water in the tank. As the water heats up, it expands and rises to the top of the tank. The hot water is then drawn off from the top of the tank through the hot water outlet.
The FHR is the maximum amount of hot water that the water heater can deliver in the first hour of operation. After the first hour, the water heater will need to reheat the water in the tank before it can deliver more hot water.
Why First Hour Rating Matters
The FHR of a water heater is important because it determines how quickly the water heater can meet the hot water demands of a household. A household with a high demand for hot water, such as a household with multiple bathrooms or a large family, will need a water heater with a high FHR.
A water heater with a low FHR may not be able to meet the hot water demands of a household, which can lead to cold showers and other inconveniences.
How to Choose the Right First Hour Rating
The right FHR for a household will depend on the number of people in the household, the size of the household, and the household’s hot water usage habits. A general rule of thumb is to choose a water heater with a FHR that is at least 2 gallons per hour per person in the household.
For example, a family of four would need a water heater with a FHR of at least 8 gph.
Conclusion
The FHR of a water heater is an important factor to consider when choosing a water heater. A water heater with a high FHR will be able to meet the hot water demands of a household more quickly than a water heater with a low FHR.
When choosing a water heater, it is important to consider the number of people in the household, the size of the household, and the household’s hot water usage habits. A general rule of thumb is to choose a water heater with a FHR that is at least 2 gallons per hour per person in the household.
Additional Information
In addition to the FHR, there are other factors to consider when choosing a water heater, such as:
Tank size: The tank size determines how much hot water the water heater can store. A larger tank will hold more hot water, but it will also take longer to heat up.
Heating element wattage: The heating element wattage determines how quickly the water heater can heat the water. A higher wattage heating element will heat the water faster, but it will also use more energy.
Energy efficiency: The energy efficiency of a water heater is measured by its energy factor (EF). The EF is a ratio of the amount of hot water that the water heater produces to the amount of energy that it uses. A higher EF indicates a more energy-efficient water heater.
By considering all of these factors, you can choose a water heater that is right for your household’s needs.