How Long Does it Take for My Water Heater To Heat Up?

Last Updated On June 11, 2024

Updated on July 22, 2021



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how long for water heater to get hot

You have successfully ignited your conventional gas or electric water heater tank system. Now, the water heater must heat the water inside the tank, which will take some time. 

How long does it take for a water heater to get hot? Numerous factors come into play, including:

  • Tank size
  • Heat Source
  • Efficiency
  • First Hour Rating
  • Age

In this PlumbingNav guide, you will learn how long it will take for your water heater to heat up and what affects the speed at which your water heater gets hot. 

***This article applies to traditional water heaters with tank systems – not tankless systems***

What's In This Guide?

      How Long Should Water Heater Recovery Take?

      The main factors determining how quickly your water heater will recover are tank size, heat source, efficiency, first hour rating (FHR), and age. Not one factor can indicate how quickly a water heater will take to heat up since all factors play a role in producing the final result.

      Factor 1: Tank Size

      Generally speaking, the larger the water heater tank, the longer it will take to heat water. Picture two pots of water on your stove- one large and one small. The smaller pot with less water will heat up much faster than the larger pot. 

      While smaller water heater tanks heat up more quickly, they may not adequately supply your family with enough hot water. If your family requires a larger tank, waiting a bit longer for the hot water heater to recover is necessary.

      Factor 2: Heat Source 

      There are two primary heat sources for water heater tanks: electricity and gas. Most gas water heaters heat up more quickly than electric water heaters due to a direct pilot light heating the water. Electric water heaters use an indirect method that doesn’t emit as much heat. While gas water heaters heat up more quickly, electric water heaters tend to have higher efficiency ratings. 

      Electric water heaters measure power based on wattage. The higher the wattage, the more quickly the water will heat up. Gas water heaters measure power based on BTUs. Like electric water heaters, the higher the BTU, the more quickly the water will heat up. 

      Did you Know How Long for Water Heater to Get Hot

      Factor 3: Efficiency 

      Energy-efficient water heaters heat the water faster and keep the water warm without letting the heat escape. Efficient water heater tanks consist of durable materials, such as steel or copper. They also have effective insulation inside the tank, usually made out of glass lining. 

      Both gas and electric water heaters come with an efficiency rating, calculated by taking the amount of hot water produced and the amount of energy required in a day. 

      Traditional water heaters with the revered EnergyStar sticker must have a UEF rating between .65 and .95, with the most efficient products receiving the highest rating. Every water heater must have the UEF clearly labeled on the tank. 

      UEF replaced the Energy Factor (EF) as the standard measurement of water heater efficiency in 2017 as it provided more accurate ratings by using a more sophisticated rating procedure.

      Factor 4: First Hour Rating (FHR)

      Want to know how fast it will take your water heater to produce hot water? Look for the first hour rating (FHR). Both electric and gas water heaters provide you with the FHR. This is the measurement of how much hot water the unit can produce within the first hour of use. The higher the number, the more hot water you have available after an hour. 

      For example, a water heater with a FHR of 80 gallons means you will have 80 gallons of hot water after an hour. A water heater with a FHR of 50 gallons means you will have 50 gallons of hot water after an hour. 

      Considering one load of residential laundry uses 40 gallons of water, you want to ensure you have a FHR that keeps up with your needs. Keep in mind that the FHR does not refer to the size of the tank. 

      Manufacturers calculate the FHR with the following formula

      Tank Capacity  x  .70  +  Recovery  =  First hour rating

      The tank capacity is multiplied by 70% to account for the cold water entering the tank and mixing into the hot water. Add the recovery rate, which indicates how much water enters your water heater when empty. You can find the tank capacity and recovery on a sticker on the tank. Keep in mind that the FHR assumes the water in the tank is within 20°F of the desired temperature. If the water heater needs to heat the water more than 20°F, it will take longer. 

      Pro Tip: Don’t want to calculate the first hour rate yourself? Locate the FHR on the tank or in the owner’s manual. 

      Factor 5: Age

      Age can take a toll on how well your water heater works due to build up in the tank and wear and tear. Even powerful, efficient water heaters can slow down at the end of its life expectancy. How do you know how old your water heater is? 

      First, look for the label, which will have the installation date. If you can’t find a label, find the serial number on the tank and use the user manual to determine the correct age of the unit. 

      If age is a factor, ask your plumber if maintenance will fix the problem. A tune-up may provide a significant improvement without replacing the entire water heater. If your unit is over 10 years old, it may be time to replace it with a new water heater

      How Long Does it Take a 40 Gallon Water Heater To Heat Up?

      A 40 gallon water heater with a FHR of 80 will recover in 30 minutes, while a 40 gallon water heater with a FHR of 40 will recover in one hour. 

      How Long Should a 50 Gallon Water Heater Take to Get Hot?

      A 50 gallon water heater with a FHR of 80 will recover in 40 minutes, while a 50 gallon water heater with a FHR of 40 will recover in 80 minutes. 

      How Long For a 75 or 80 Gallon Water Heater to Heat Up?

      An 80 gallon water heater with a FHR of 80 will recover in 60 minutes, while a 80 gallon water heater with a FHR of 40 will recover in 120 minutes. Similar math is used for 75 gallon units.

      FAQ’s For Turning on Electric Water Heaters

      How do I make my water heater heat up faster? 

      Want to make your water heater warm up more quickly? Buy a water heater blanket to insulate the water heater. They are inexpensive, surprisingly effective, and easy to install yourself. If that still doesn’t provide adequate improvement, schedule professional maintenance to get the unit clean. 

      These two solutions should help, but if all else fails, you get the opportunity to practice your patience until you get a new water heater. 

      Why does it take so long for hot water to get hot?

      Your water heater tank holds a lot of water. A large tank means you have a considerable supply of hot water- once it’s hot. It takes some time to heat up, but the job gets done within an hour or two. However, some hot water tanks take longer than promised. 

      First, check that you turned the water heater on correctly. If the problem still persists, the water heater tank may require maintenance or the system may require repair. If your standard home water heater still isn’t warm after three hours, call a plumber. 

      What heats up that fastest, gas or electric water heaters?

      Gas water heaters tend to heat up faster. However, many other factors come into play. A brand new, more efficient electric water heater with a smaller tank will heat up faster than many gas water heaters. Examine the water heater in question to get the specific first-hour rating. 

      Hybrid energy-efficient water heaters and tankless water heaters heat up almost instantly. While most people don’t mind waiting an hour or so to recover the water heater, switching away from your water heater tank can solve your problem for good. 

      If interested, ask your plumber if you are a good candidate for a change. 

      Final Thoughts

      Recovering your water heater or installing a new water heater? You no longer have to guess how long it will take to heat up the hot water. This guide gives you all the information you need to know how long you should give your hot water heater before enjoying a hot shower.

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      About Plumbing Navigator

      We write about "all things plumbing," helping you navigate common questions, repairs, and the best plumbing products on the market.

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      We write about “all things plumbing,” helping you navigate common questions, repairs, and the best plumbing products on the market.

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