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

homedude is reader-supported. When you buy through links on our site, We may earn an affiliate commission. Learn more

Some variables should be considered if you want an efficient water heating system that will meet your hot water needs when you need it and for as long as necessary, especially after the tank runs out of hot water.

One is the amount of water getting heated, another is how it gets heated, and the third is the heating rate or capacity of the heater. And then the recovery rate, which is the time taken to reheat a tank of water after use.

So, how long does it take for a hot water heater to heat up? The answer is quite simple. The amount of water you are heating, plus the amount of heat you’re putting into it, will determine how long it would take for you to get fresh hot water. On average, it will take around 30 to 45 minutes to fully heat up a hot water heater.

Perhaps you’re wondering if it is taking longer than necessary for you to get your water heater up; read on.

The BTU Rating And Tank Size

The first thing you must be familiar with is the BTU rating of your heater. The BTU is the British Thermal Unit which translates to the amount of heat required to raise one pound of water by one degree Fahrenheit. The higher the BTU rating of your heater, the faster it heats the water of a particular volume.

Water heaters are ranked by BTU rating, which in practical terms means BTU per hour or BTUh. This means that a 40,000 BTU heater will heat 44,000 pounds of water by one degree in an hour. Alternatively, it can heat 440 pounds of water by 100 degrees.

Next, you should know that tank size also plays a major factor. The larger the size of the tank, the longer it would take to heat up.

For the average water heater, the tank is about 40 gallons, and it takes about 30 to 40 minutes to heat fresh water in the tank. 

How Does A Water Heater Work?

Let’s look at how it works.

Let’s assume your heater has a 40,000 BTU rating, fitted with a 40-gallon tank. It would take half an hour to heat the tank. This is because each gallon needs half of a minute to heat up. A gallon equals about 8.3 pounds.

If the BTU rating is higher, with the same tank capacity, it will take a shorter time to heat up. If, however, the tank is larger with the same BTU rating, it would take longer.

So, in simple terms, the smaller the tank, the shorter the time, and as expected, the higher the BTU rating, the faster the water would heat up.

If you have a small family, it is better to use a smaller tank. However, for a large family in need of hot water for a long time, you will need a bigger tank.

Gas Heater Or Electric Hot Water Tank?

The water heater recovery rate of a gas heater is higher than that of an electric water heater. That means it is faster to get hot water from a gas heater than an electric hot water tank.  

While they are more economical and cost-effective, electric tanks take twice as much time to heat up than a gas heater. When cold water enters the tank, it may take as long as half an hour to heat a 40-gallon tank.

The greatest advantage of gas-powered water heaters is that they have a faster recovery rate. For large homes, this is the ideal option.

Although electric heater tanks are more energy-efficient, the eventual power cost sometimes makes gas-powered water heaters an even cheaper option.

What’s more? During emergency power outages, gas-powered water heaters continue to deliver the supply of hot water, while electric water heaters would pack up.

However, for smaller homes with minimal needs for hot water, the electric water heater is perfect. While a gas tank uses the heat generated from natural gas to heat the water, an electric water heater uses coils.

The lack of energy efficiency is a huge problem with gas tanks, though. While this means you’ll always have a hot water supply almost immediately it is needed, it leads to lots of wasted energy.

Are Tankless Water Heaters Efficient?

A gas water heater and electric tank water heater are very common. However, the tankless water heater is beginning to gain popularity due to its many advantages. The greatest selling point of the tankless heater is its energy efficiency.

Regular water heaters are also efficient and can be functional for many years, but tankless water heaters not only conserve energy better but are also cheaper in the long run, despite their huge initial cost.

Storage tank water heaters normally have an average capacity of 50 gallons and make use of natural gas, electricity, fuel oil, or propane, and often keep hot water ready for use at any time, so you have access to instant hot water. However, keeping water hot when you don’t need it is costly.

However, a tankless heater does not have a storage tank. Rather, this hot water system heats cold water as it passes through a heat exchanger to rapidly increase the temperature of the incoming water. So, it only heats water when needed, cutting the energy loss of keeping water heated when not yet needed.

The only disadvantage is that it is costly to install and replacing your electric water heater and gas water heater may be more costly. But overall, it is efficient and effective and heats water in a short time.