How Long Does It Take a Water Heater to Recover?

October 25, 2017

If you’re wondering how long it should take your tank water heater to reheat once the water is depleted, the answer is: 

It depends on a lot of different factors including the:

  • Water heater size
  • “First hour rating”
  • Fuel type
  • Temperature “rise” 

But to help you answer this question, we’ve listed average water heater recovery times below:
The average 80-gallon gas tank water heater takes 60-70 minutes to heat up
The average 80-gallon electric tank water heater takes around 2 hours to heat up

* These numbers assume an incoming water temperature of around 62°.

Think your water heater is taking too long to heat up based on these numbers? Don’t worry. We’ll explain some problems that can result in abnormally long water heater recovery times and tell you what you should do to fix the problem.

But first, let’s take a quick look at the factors that determine a water heater’s recovery time.

Need a professional to determine why your water heater takes too long to recover? Just contact us.

Some factors that affect how long a water heater takes to heat up

1. Water heater size

How it affects recovery time: The larger the water heater, the longer it takes to heat up.

Traditional tank water heaters are sized according to how many gallons of hot water they can hold at once. Most residential water heaters range from 20 to 100+ gallons. And the more gallons of water a water heater holds, the longer it will take for the burners/heating elements to heat the water.

2. First hour rating (FHR)

How it affects recovery time: The higher the first hour rating, the shorter it takes for the water heater to heat up all of its water.

A water heater’s first hour rating basically tells you how many gallons of water the unit can supply in one hour—starting with a full tank of hot water. 

3. Fuel type

How it affects recovery time: Electric water heaters take roughly twice as long to heat water than gas water heaters.

Gas water heaters are, across the board, much faster at heating water than electric water heaters. That’s because the gas burners in a gas water heater can reach much higher temperature than the electric resistance coils in an electric water heater.

4. Temperature rise

How it affects recovery time: The higher the temperature rise, the longer the recovery time of your water heater.

“Temperature rise” simply refers to the difference between the temperature of the incoming water and the temperature you want it to be heated to.

So, calculating your temperature rise would look something like this:

Desired hot water temperature - Incoming water temperature = Temperature rise

Incoming water temperatures across the U.S. Source

So, if you’re a Tampa homeowner, your incoming water temperature (according to the map above) is around 72°. So, let’s say that you prefer your hot water to be around 120°. Your temperature rise would be 48° (120° - 72° = 48°).

Basically, the bigger the difference between incoming water temperature and the set temperature of your water heater, the longer the recovery time.

So now that you have a better idea of what factors affect your water heater recovery time, let’s look at some problems that might cause your water heater to take longer than it should to recover.

If your water heater suddenly takes much longer to reheat...

...you most likely have sediment buildup.

Sediment buildup happens when the dissolved minerals in your water (calcium and magnesium) settle onto surfaces inside your water heater. Over time, this creates a thick layer of sediment that can restrict your water heater’s ability to heat water.

And because Tampa has “hard” water (that is, water with a lot of dissolved minerals), sediment buildup happens quickly in water heaters in this area (especially if you don’t have your water heater regularly maintained).

Signs that you have sediment buildup in your water heater:

  • Your water heater makes a popping/knocking/hissing noise
  • Higher-than-normal energy bills
  • You run out of hot water faster than you used to

What to do:

Have a professional inspect your water heater. They’ll confirm whether sediment buildup is your problem or not.

If it is, they’ll flush your water heater to get rid of the sediment buildup.

Other problems that can cause a water heater to suddenly take much longer to heat up include a broken thermostat, a broken dip tube or bad burners/heating elements. Unfortunately, you’ll need a professional for these particular water heater repairs.

If your water heater’s always had abnormally long recovery times…

...you most likely have a water heater that’s too small for your needs.

If your water heater is too small for your hot water needs, it’s likely that you’re drawing too much hot water from the tank, which quickly depletes your hot water supply. And because the tank is much too small, you’re likely continuing to draw hot water which means the tank can never catch up and fully recover.

What to do:

Have a professional inspect your water heater. They’ll determine whether the water heater is too small for your needs. If it is, they’ll also suggest a more appropriately sized water heater for your family and can provide a quote for your water heater replacement.

Another issue a plumber can check for is an incorrectly installed water heater. For example, if the tech who installed the unit turned on the circuit breakers for an electric water heater before the tank was full of water, the heating elements may have overheated, limiting its ability to heat water quickly.

Need help from a Tampa plumber?

If you’re still not sure whether your water heater recovery time is too slow, just contact us.

We can take a look for any water heater issues and fix them in no time.

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