Estimating Hot Water Needs: What Size Should You Get?

In general, your hot water needs can be measured by the number of bathrooms in your house. The smallest size unit for a one-bathroom house should be 30 or 40 gallons, in either gas or electric. For a 1 1/2-bath house, 40 gallons is minimum. For a 2- to 3 1/2-bath house, choose a 50-gallon gas heater or a 66- to 80-gallon electric one.

However, the demands of the household and whether or not the water heater is fueled by gas or electric power also make a difference in the size you would need. Every household is different, using different amounts of water at different times of the day. The peak hour usage of the household is one figure that Plano plumbers like ours at Harvey West Plumbing use to determine the right size of water heater for customers.

You can always call us or your local plumber if you need to figure out what water heater size the household truly needs. If it’s time for replacement, you can also opt to switch to a tankless water heater so you can have instant hot water for everyone whenever you like. If you did this, then all the figuring on the right size and type would be unnecessary. Here are some other considerations that may help you figure out the size of water heater to install in Plano.

Electric Considerations

Electric water heaters take longer to heat water, so the tank should be larger than one fueled by natural gas or propane. For example, a large, four-bath house or a home with an extra-large bathtub would need at least a 75-gallon gas heater or a 120-gallon electric heater. Some different dynamics and circumstances can skew these standards. For example, a laundry-heavy family with small children or a house with an especially large garden tub will need a much larger water heater than normal.

Water Heater Sizes

Water heaters come in three basic sizes including 23-36, 36-46, and 46-56 gallons but you can find larger ones if necessary. You can find out how large your current tank is by looking at the nameplate. A good rule of thumb is that you can usually replace your old one with a new one of the same capacity unless you’ve recently added a bathroom, dishwasher or washer or are planning a new addition or appliances in the near future. You might also want to take advantage of the newer, more energy-efficient models.

Gas vs. electric

In general, gas water heaters win the battle. A water heater’s capacity is a result of two factors: storage and recovery time (how quickly it can heat a tankful of water). With recovery, both gas and electric water heaters are rated by the number of gallons of water they can raise to 90 degrees F in one hour.

For example, a 40-gallon gas heater rated at 40,000 BTU can “recover” more than its entire capacity (41 gallons) in one hour. A similar capacity electric heater running at 240 volts will only heat half of its capacity (20 gallons) in an hour. Propane heaters are most often found in rural areas.

Peak Usage & Family Size

Peak usage, or peak hour demand, is an important consideration when determining the size of water heater to install. Figure out what time of day or hour that hot water is normally used most throughout your household. You will need to estimate the maximum amount of hot water which is used during this hour by the number of people living in your home. This is different than figuring the total daily usage.

During the peak hour, count how many people are doing specific things like:

• 3 showers
• 1 shave
• 1 automatic dishwashing
• 1 gallon for food prep and veggie rinsing
• etc.

Here are the average gallons used during these activities:

• Shower 10 gallons
• Shaving 2 gallons per minute
• Food prep 4
• Dishwashing 6
• Clothes washing 7 (only if using hot or warm water, adjust down to 4 for warm)

For a household that takes 3 showers a day, 1 shave, 1 dishwashing, and food prep hot water during the peak hour, the total usage would be:

• 30 (shower)
• 10 (5 minutes of shaving)
• 4 (food prep)
• Dishwashing (6)
• Total: 50 gallons during peak hour

For this household, a 46 to 56-gallon capacity water heater would need to be installed. Of course, there are always options in tank size, but you don’t want the water heater heating the water all day and night for no reason when you may need that much only once in a blue moon. Also, remember that gas fueled water heaters work faster so you won’t need as large of a tank.

If you're looking for information about Estimating Hot Water Needs: What Size Should You Get? then please call Harvey West Plumbing at 972-509-0224, or fill out our online request form.