Water Heater


In choosing the right water heater for your home, bigger in size is not necessarily the best choice. If you buy a tank that is too big, you’ll just be wasting your money. If it’s too small, you may not have enough supply of hot water before you finish your shower.

The trick in getting the perfect size of this heating device is to follow some important guidelines that may be of help to you. Determine the first hour rating or FHR of your home. FHR is the amount of hot water that the heater can deliver at a busy hour during the day. You’ll find it on the heater’s Energy Guide label.

Do-it-yourself formula in determining the first hour rating

The DIY formula in getting the first hour rating is based on the busiest hour of the day when hot water is used heavily in the home. It includes baths, showers, washing hands, dish washing, brushing teeth, shaving and using the washing machine. When 2 or more of these things are used at the same time in 1 hour, then, it is considered the peak usage hour.

  • If you want to get the FHR by yourself, you can use the formula below in a 4-bedroom house example:
  • Prepare 12 gallons of hot water for each person in your household.
  • Use the formula on how many bedrooms in your home plus 1 to get the maximum occupancy. In this example, there are 4 bedrooms, so, if 1 is added, you get a total of 5. By multiplying this number with the 12-gallon allotment, you get an FHR of 60. Therefore, this number is the minimum FHR for this sample home that the water heater requires.
  • The next one to determine is the energy factor, or EF. If your EF is higher, your tank would be more efficient. In the above example, the aim is to get the highest EF rating for a tank having an FHR of 60.

If you cannot do it yourself, you can consult a contractor to do it. One great thing is that today it’s easier to determine the most appropriate size water heater for your home that is cost-efficient. Before, building codes and complicated tables or specific standards imposed by the Department of Housing and Urban Development were used by contractors. So, next time you buy a water heater, follow the above tips to save money on usage.