How Long It Takes a Water Heater to Heat Up

How Long It Takes a Water Heater to Heat Up

As one of the most blissful luxuries in life, a hot shower is necessary not only for cold, lazy mornings but also before going to bed, as it soothes and removes remnants from your long, arduous day. However, standard faucets do not produce hot water, while the electric tankless water heater only creates a limited supply of hot water for your convenience.

As a result, you get irritated about running out of warm water in the middle of the shower, while wondering what you must do with this problem. Thus, seeking for the best hot water heater model is a recommendable choice, which starts in knowing the answers to, How long does it take for a hot water heater to heat up?

To cease all of the endless yet typical inquiries about water heaters and its varieties, including sizes, types, and fuels or source power, here are the influences that significantly impact this matter.

Factors that Influence the Water Heater’s Heat Up Speed

  • First Hour Rating

So, how long does it take for a water heater to heat up? 

Knowing the first-hour rating is the kick start to answer this question. This factor indicates the number of gallons that the water heater can transport in or within the first hour. Moreover, it is also a sign of how capable the water heater is after carrying tons of water after it recovered a full to your desired temperature. When the first-hour rating is high, then it means a shorter waiting time. It depends on its fuel source, capacity of the tank, and size of the burners, or any heating elements.

  • Size of Water

Another factor that can lengthen the heat time is the size of your water heater, so you must also consider this fact too. In this case, the larger the size of your water heater is, the longer it takes for it to heat up. The smaller it gets, the quicker it heats up. The reason behind this is not complicated – heat time slows down as there is more water to heat in larger tanks.

Aside from the capacity of a larger tank, it also has two heating elements, like a massive burner to quicken speed up heat time. Despite this feature, smaller containers still heat up quicker, but they run out faster than larger ones. Hence, you need to make sure to choose a water heater that is suitable for your personal use.

  • Inlet Water Temperature

Inlet water temperature means a temperature rise, which is one of the factors that could severely affect the recovery time. The temperature rise implies the temperature contrast between the preset temperature on the boiler and the incoming water (inlet). The colder the inlet water is, the longer it takes for the water to heat up. The inlet water temperature depends on where you live, as it is colder up North than in the South, for instance.

  • Fuel Type

Water heaters have various classifications, including its sizes, types, and fuel or power sources. Being one of the most traditional but effective ways of heating water is a gas boiler. Gas water heaters are also faster than its electric cousins because of its fuel type. Gas burners reach a higher temperature than those of electric heating elements.

Choosing the Best Water Heater For Quick Heat Time

Before randomly purchasing a water heater, have you asked yourself, How does a water heater work? Determine the following features as well as some calculations that you need to get the perfect water heater for you.

Determine the Size and Capacity

How long does it take an electric hot water heater to heat up? Is it the same with other electric heaters with different sizes?

Water heaters vary in the make and capacity that determines the length of heating the water in an electric water heater; the same goes with the traditional water heaters. 

The capacity and size of the water heater significantly affect the time it takes for the water to heat up. If you are not that patient to wait for the water to get heated, you should not get a size larger than 40-gallon capacity (standard size), as the bigger the size, the longer the heat up can take.

Know the Water Heater Type

The common types of water heater include gas, electric, solar, and tankless, which is crucial in the length of the heat time.

  • Gas heaters – take at least 30-40 minutes to heat a full-tank water
  • Electric heaters – twice as long as gas heaters, which is more than an hour.
  • Solar heater – almost similar heat time with electric ones, as it is usually connectable with the electric heaters
  • Tankless heaters – provides an unlimited supply of hot water with no warm-up time, however, expensive

Compute How Long Does It Take For A Hot Water Heater To Heat Water

The calculation for heat time is not complicated because you only have to determine how long you want to shower and deduct the minutes of remaining hot water. Then, multiply the difference by 4.3 (electric heaters) or by 1.9 (gas heaters).

The other method involves knowing the total minutes of hot water in the tank and subtracting it from the number of minutes the last person used the hot water.

For instance, how long does it take for a water heater to heat up 50 gallons?

Water heaters with 50-gallon tank capacity take 31 minutes of hot water for electric heaters and 50 minutes for gas heaters.

Check for Sediment Buildup

There would be a time that your water takes too long to heat, especially if you have always been using the same water heater for a while. Always have a water heater checking for built-up sediment cases. Sediments are a mix of dissolved materials like magnesium and calcium that sinks to the bottom of the tank and settles there. This sediment buildup can displace the amount of hot water you can put in the tank, leading to:

  • Less water availability; and
  • Longer heat time between refills.

Thus, it is essential to determine the time it takes for the water to heat up to know if your water heater is still in good condition. It gives off signs whether your water heater must get a check-up or if you badly need to replace it with a new one.


To sum it up, heat time also depends on factors that you might have been ignoring for a while. Although gas heaters are significantly quicker than electric ones, it can also depend on the sudden increase in recovery time, which signifies sediment buildup. For this problem, you can flush the water heater tank or call for professional help if it needs replacement.

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