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How Long Does It Take for a 50 Gallon Water Heater to Heat Up?

Fact checked by Stephen Conklin

how long does it take for a 50 gallon water heater to heat up

We often hear first-time water heater owners ask, how long does it take for a 50 gallon water heater to heat up? Although a new water heater can deliver refreshing hot water within 30 to 45 minutes, some units might need more than 2 hours to accomplish the task.

Several factors can influence a hot water heater unit’s heating time, such as first-hour rating, water heater type, energy source, heating capacity, and more.

You can look at the following table to learn these variances. Read on to learn more valuable information.

Parameter (Temperature differential to reach 120 degrees Fahrenheit) 50-gallon Gas Water Heater 50-gallon Electric Water Heater
50-degree temperature rise 33 minutes 66 minutes
60-degree temperature rise 40 minutes 80 minutes
80-degree temperature rise 53.5 minutes 107 minutes

Water Heater Type and Heating Times

How long to heat a 50 gallon water heater depends on the water heating appliance type. This factor considers the device’s power source, whether electric-operated or gas-fed.

In general, for a 50℉ temperature rise, a 50-gallon heater will require 33 minutes, whereas an electric unit will take up to 66 minutes. Why is there such a huge discrepancy? Read and find out.

1. Gas Water Heaters


As a rule, a gas water heater elevates water temperatures faster than electric units. The average gas-powered heater uses 40,000 British Thermal Units (BTUs) to warm the water. This figure equals 11,730 watts or 11.73 kilowatts (1 watt = 3.41 BTU).

Even if the gas-fed unit only has 30,000 BTUs, its wattage equivalent (8.8 kW) will still be higher than a similarly-sized electric heater.

The gas heater’s higher heating capacity allows it to raise water’s temperature twice as fast as electric versions. Hence, if an electric heater needs two hours, a gas-fed unit will only need an hour to heat hot water tank.

2. Electric Water Heaters


A 50 gallon electric water heater uses about 4500 watts or 4.5 kilowatts of electricity to heat the water. Converting this figure to BTU will give us 15,345 BTUs (4500 watts x 3.41 = 15,345 BTUs).

The electric unit’s lower BTU than a gas-fed unit explains its extended heating times. For instance, 90 minutes might be necessary for a water heater to heat up 50 gallon, while a gas-powered version might only need half the time.

Unfortunately, differentiating between a gas and electric water heater only tells you that one is faster than the other. It does not reflect the answer to the question, how long does a 50 gallon water heater take to heat up?

Water Heating Times and Water Heater Ratings

Water heater manufacturers test three parameters for their respective products. These factors can influence how fast the appliance can heat the water to the desired temperature.

1. Draw Efficiency


This rating reflects the unit’s ability to raise the whole storage tank’s water temperature. We must reiterate that a water heater does not heat the tank’s rated capacity.

We cannot expect a 50 gallon gas water heater or an equivalent electric version to heat all 50 gallons. Cold water also enters the tank just as we use hot water.

So, how much water should the water heater warm up? Its draw efficiency should be at least 70 percent. Hence, a 50-gallon unit should elevate at least 35 gallons to the ideal temperature.

2. First-Hour Rating (FHR)


How much water flows out of the heater at the desired temperature in one hour reflects the device’s first-hour rating (FHR). The ideal 50-gallon heater must deliver 60 to 80 gallons of hot water within an hour of operation.

Water heater manufacturers determine the FHR by setting a three-gallon-per-minute device to 135℉ and using hot water until its temperature drops to 110℉. They then restart the test several times to account for one hour.

The total volume over one hour reflects the water heater’s FHR. This rating is one of the best pieces of information to look for when determining peak hot water usage. At least, you will know your water will stay hot when it is your turn at the shower.

3. Recovery Rating (RR)


Some folks confuse this rating with FHR because it reflects the volume of water the device heats per hour during consumption. A more “accurate” description will be the appliance’s speed to “reheat” or “recover” the ideal water temperature.

The heating speed depends on the heater’s power source. We already know electric water units are roughly twice slower than gas versions. But let us look at a few examples.

  • Suppose you want a 120-degree shower, and the water entering the storage tank is 60 degrees. In that case, the 50-gallon electric water heater recovery time will be 80 minutes. On the other hand, a gas unit will only need 40 minutes to “recover” the 60-degree temperature difference.
  • To increase the water temperature by 50 degrees, you’ll have to wait 33 and 66 minutes with gas-powered and electric heaters, respectively.
  • A colder water inlet temperature of 40℉ will push the “recovery” times further. An 80-degree temperature rise (to 120℉) demands a 107-minute wait from an electric water heater or a 53.5-minute heating time from a gas version.

Device ratings are not the only influences impacting a water heater’s water heating speed, especially after installation.

Other Factors Affecting Water Heater Heat-up Time

Our preceding discussion points to other factors influencing water heater heat-up times. Understanding these parameters can help us determine a more definitive answer to the issue of water heater heating speed.

1. Inlet Temperature


As mentioned above, a higher temperature rise takes longer to heat. For example, raising the water temperature from 40 to 120℉ will take 53.5 minutes to 107 minutes, depending on whether the unit is gas-powered or electric.

2. Water Heater Integrity


Sediment and limescale buildup can impact a water heater’s heating speed. Failure to observe maintenance procedures or basic care requirements can also impair the appliance’s heating performance.

You cannot expect your water heater to heat the water fast even after reset if you do not fix maintenance and age-related issues.

4. Location

The distance between the hot water fixture or faucet and the heater can also impact the heating speed. The closer your shower is to the appliance, the faster it will warm up.

5. Water Pipe Diameter


Although large-diameter pipes deliver more hot water at once, these plumbing fixtures can extend water heating times.



What is the average lifespan of a 50-gallon water heater?

A question that frequently bugs first-time owners is, how long does a 50 gallon water heater last? A water heater with this capacity can last anywhere between eight years and two decades.

Observing proper and timely maintenance procedures can extend the water heater’s lifespan. Meanwhile, neglect and shoddy operation can lead to the appliance’s earlier-than-eight-years demise.

Is a 50-gallon electric water heater more efficient than a 40-gallon version?

If you compare an electric 40-gallon water heater to a high-efficiency 50-gallon unit, the latter would be more energy-efficient. This is because a 50-gallon unit has more hot water in the first place, thus requiring less frequent reheating.

However, energy efficiency advantages will be negligible if both water heaters have nearly identical Uniform Energy Factor (UEF) values.


Determining how long does it take for a 50 gallon water heater to heat up can be tricky because several factors can influence a device’s heating speed. Although gas-powered units heat water faster than electric versions, appliance ratings can impact the final outcome.

Drawing efficiency, first-hour delivery, and recovery rating are critical influences on heating speed. So are groundwater temperature, heater integrity, pipe diameter, and location.

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