“What size water heater do I need?” There isn’t a one-size-fits-all answer to this question. It depends on your personal needs and how much water you use during the day. To find the right size for your household, you’ll need to do some math.
Don’t worry, though. It’s not as complicated as you think. As long as you know how to add, you’ll be good to go. To help you determine what size water heater you need, we have put together a guide to help you determine the amount of water you use.
Calculating Your Needs Before Choosing a Water Heater Size
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If general numbers are enough for your needs, you stop here. But the estimates above are just averages. To get the exact right water heater size for your house, you need to do a few calculations that are a bit more complicated.
Find the First Hour Rating
A water heater’s first hour rating is the amount of warm water the heater can produce in a single hour. After you use all this water, the water heater will have to warm up more water, which will take some time. Because of this, the water that comes out of your faucets will be cold until the water heater gets back to its full FHR (first-hour rating).
If the water heater can produce 50 gallons an hour, the first hour rating would be 50. You can find the heater hour rating on the energy guide label.
Figure Out the Peak Hour Demand
Once you know the FHR, think about how much water your household uses in your peak hour demand. The peak hour is the period of time you and your family members use the most water at the same time.
For example, let’s say your peak hour demand happens in the morning before you head to work and the kids go to school. You might need to take a shower, and you all might have to wash your hands.
Use the chart from Energy.Gov to figure out how many gallons you’ll use in total:
- Shower – 10 gallons
- Shaving – 2 gallons
- Washing hands – 2 gallons
- Washing dishes (by hand) – 4 gallons
- Washing dishes (dishwasher) – 6 gallons
- Washing clothes – 7 gallons
Add the number of gallons your household uses together. Two showers equal 20 gallons. If four people have to wash their hands in the morning, that would be 8 gallons. Altogether, you would need a water heater with an FHR of at least 28 gallons.
What Size Hot Water Heater Do I Need?
Before you start sorting through the different types of water heaters on the market, you need to figure out how much hot water your household uses a day. Skipping this step might leave you with a water heater that doesn’t have the tank capacity you need, leaving you to wash your hair in a cold shower!
There are a few simple ways to do this calculation. Start by asking yourself the following questions.
What Size Is Your House?
In general, larger houses will need bigger water heaters than smaller houses. This isn’t always true, but since larger houses have multiple bathrooms and more appliances, they require more water.
How Many People Live There?
A better way to estimate your water usage is to judge the amount based on how many people live in your house. Count all your family members, then add any extended relatives (or other people) that spend a lot of time at your house, such as children that split time between you and your ex-partner.
- -One to two people need a tank capacity of 23 to 36 gallons
- -Two to four people need a tank capacity of 36 to 46 gallons
- -Three to five people need a tank capacity of 46 to 56 gallons
If you have more than five family members living in your house, add an additional 10 gallons for each person. Based on these numbers, a 50-gallon water heater will give a family of five all the warm water they need.
Keep in mind that it’s always better to overestimate than underestimate. However, if you’re worried about spending too much money on water you won’t end up using, you can always talk to a professional plumber for a more accurate estimate.
Replacing Your Old Water Heater
Did your old water heater recently give out? You might be able to stick with the same size when you buy a new one. If you haven’t had a problem with your warm water production, all you have to do is install a water heater the same size as your old one. This should give you all the water you need, and you won’t have to do any math.
However, if you’ve had a new addition to the family (or plan to grow your family in the near future), you might want to go ahead and upgrade in advance.
4 Factors To Consider When Purchasing
Hot Water Heater Location
Especially when replacing a larger unit, your hot water heater location matters. Worst-case scenario: a new water heater won’t fit in your existing space. This requires you to build out space to accommodate your device better, meaning more money and more hassle. Ensure that your water heater replacement fits your desired space.
Also, consider other spaces. Homeowners typically tuck away water heaters in the garage, basement, attic, or crawlspace. Placement not only affects how fast water will heat your bathroom and kitchen, but it’s also important to note the potential damages that could occur if your water heater were to leak.
Amount of Warm Water You Use
This is also known as the flow rate. Ask yourself, how much water am I using at any given time? Many water heaters will struggle to keep up with the high-flow water demands. For example, if you have a spa tub, rain showerheads, or a larger household—these factors can alter your hot water heater purchase decision.
If you have a high-flow rate, consider new energy-efficient standards, fuel source type, groundwater temperature, and more when making the final purchase.
Temperature of Your Groundwater
Lastly, you’ll need to ensure your home is sized properly. You do this by calculating how much power is needed to reach the desired temperature.
Groundwater temperature is your starting point. For those living in a colder climate, more power is required to heat your water than if living in a warmer climate. Use groundwater temperature maps to best identify the groundwater temperature in your area. You can also allow a professional to properly calculate your groundwater temperature as well.
Type of Water Heater
The fuel source you’ll use is one of the first steps to purchasing a water heater. Fuel source matters, and depending on many variables, one may benefit your home better than the other.
For example, natural gas water heaters tend to have a higher initial price, but in the long term, they cost less to operate on a monthly basis. Additionally, natural gas heats water faster and has high energy-efficiency models available. On the other hand, it’s hazardous to the environment and even dangerous in the case of a gas leak.
Propane is one of the safest, non-toxic options but may be more expensive—especially if converting from gas or electric to propane. Electric has a lower initial cost and requires less maintenance. On the contrary, you’ll experience a higher monthly cost and risk having no hot water during a power outage. Weigh the pros and cons of each device to determine which works best for you.
How to Install a New Water Heater in Your Home
“What size water heater do I need?” Once you find the answer to that question, the best way to get through the installation is to hire a professional plumber. They’ll have the system set up quickly, and you can feel assured it will do what it’s supposed to do when they leave.
Water Heater Repair & Installation
If you need help choosing a water heater size, don’t hesitate to get in touch with our team of local plumbers. We offer water heater repair and installation services to homeowners in areas such as Denton, Wilmington, Drexel Hill, Dover, and Upper Darby. In addition, our staff of technicians offers other types of plumbing services such as water softener repair, sump pump installation, and water line replacement. We’ll help you pick the right water heater size for your needs and get it running.