Water heaters are designed with some sort of heating element that raises the temperature of water. The element can be either gas-powered or electric. There are two versions of water heaters: those with tanks and those without.
Water Heaters With Tanks
Water heaters with tanks aren’t all the same size. There are tiny versions that hold only 20 gallons, which isn’t really even enough to do a single load of laundry. In the 21st century, however, such small water heaters are no longer practical. One shower requires 20 gallons by itself, and just one load through a dishwasher, even a water-saving model, uses 14 gallons.
In 2024, and beyond, the minimum practical size of a water heater tank is 40 gallons, and that would just be enough for one person, perhaps two. In most cases, though, a 60-gallon tank is better for two people. Bigger families would need 80 gallons or more. There’s a simple rule if you have a big family: Start at 80 gallons, and then add 10 gallons to the size of the tank per person beyond five.
The key concept in the function of a water heater with a tank is called the “first-hour rating.” That number, which is also called the FHR, indicates how many gallons the water heater can heat in 60 minutes. Most of the time, the FHR should be more than the number of gallons in the tank. Some larger tanks for big families might have an FHR of 200. The idea is to heat that number of gallons “off the top” so that people who use the tank during the early part of the day don’t “use all the hot water.”
For example, let’s say that a family of four has a water heater that holds 60 gallons and has an FHR of 125. Three people get up and take showers. That takes up all of the original 60 gallons that were in the tank. However, the FHR shows that the tank has the capacity to heat the next 65 gallons that come into the tank to replace the already-used water. Given that a “normal shower” lasts about 10 minutes, it means that the fourth family member will still have hot water and also that someone can do a load of laundry without “using all the hot water.”
Contrast this with the same family making do with a 60-gallon tank with an FHR of only 80. Unless they stagger their bathing and laundry, someone’s going to wind up with a cold shower.
When it comes to water heaters with tanks, their chief benefit is that they’re much less expensive off the top than tankless water heaters. Their downside is that they’re more expensive to run over the long term.
Tankless Water Heaters
Tankless water heaters provide a steady flow of hot water instead of heating it in a tank for use later. Their rating is in gallons per minute rather than total volume and FHR. The reason that these water heaters don’t cost as much to run is that they don’t run constantly. When considering a tankless water heater, multiply the number of people living in the home by two. That’s the minimum rate in gallons per minute that will be needed. If you have frequent guests, then add another two gallons per minute to the rating of the tankless water heater you have installed.
Benjamin Franklin Plumbing
We’re both experienced and knowledgeable when it comes to both tankless water heaters and those with tanks. We’re also dedicated to superior workmanship and empathetic customer service. By earning both full accreditation and an A+ rating from the Better Business Bureau, we’ve shown our integrity and skill in the industry. Give us a call today to make an appointment to discuss your needs when it comes to water heaters.