When you run out of hot water well before you jump into the shower, you know you need to change something. A bigger water heater will help you get through those busy mornings with enough hot water to go around. But what size do you need? If you’re in a family of five, this might be an especially challenging problem. Few homes come equipped with water heaters of the right size for larger families, so you may find you need to upgrade. Here’s what you need to know to estimate the water heater size you need.
Water Heaters in General
In general, a family of five needs a water heater that is somewhere between 60-80 gallons.
If you have a 50-gallon heater that will fit the needs of four people. A 40-gallon heater is for three people or so, and homes with one or two people typically need 30-gallon heaters.
Of course, this is just a basic estimate. The more people in your family, the more likely it is that number isn’t correct. Each person brings in variability, like how long they like to shower for, when, and what other appliances that use hot water need to run in order to meet their needs. You can do a more specific measurement below.
When you demand the most from your water heater, how much do you demand? This is the question of peak hour or the hour in which your water usage peaks. In a household of five, this is probably the hour in which a few of you shower, or at the tail end of your showers if you all tend to shower back-to-back.
You need to calculate how many gallons of hot water you’ll use during that. You’ll need to know how many gallons of hot water your shower head will run in the hour. If another appliance will be running that hour, like the bathroom sink, the kitchen sink, or the dishwasher, then you also have to know how many gallons they will consume.
Every appliance or fixture will have a flow rate in gallons per minute, gpm. You can estimate how long you’re using each appliance or fixture, then add up the gallons that they will use. Add that to your shower amounts, and you’ll have the gallons you need to use in the peak hour. Your water heater will need a first-hour rating (FHR) higher than that number.
The Problem of Multiple Showers
What happens if you’re using a great deal of hot water back-to-back? In a home with five people, potentially with teenagers who like to take their time in the shower, you might have two peak hours back-to-back. Then, you should look into the recovery time of the water heater or how soon it can fill its tank back up with hot water. Gas heaters are always faster than electric heaters, so it is wise for large families to choose gas when they can.