There isn’t much that can ruin your day quite as quickly as an ice cold shower, and if you have the wrong water heater, this could become your new normal. If your current heater is dying on you, don’t let the stress of the situation rush you into making the wrong choice for your replacement.

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Before you choose a water heater, make sure you consider how long it takes for your water heater of choice to heat up. If you want to run lots of hot water at the same time, you’ll need a more powerful system than if you just want to have a daily hot shower.

So, how long does it take a water heater to heat water once it reaches the appliance? While there are many factors which can affect the time, the chart below shows how long each type of water heater takes to heat up on average.


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How Long It Takes A Water Heater to Heat Up For The First Time

Water Heater TypeTime Takes to Heat Up
Gas Tank
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Electric tank water heaters typically require double the amount of time compared to their gas counterparts. Electric elements, while typically more economical, simply cannot compete with the high performance of gas-fired systems. From the time new water enters, it would take about an hour for an electric water heater to warm the 40-gallon tank described above.

This is why homes with larger water demands usually decide to purchase a whole house gas tank water heater instead of an electric model. Electric models are excellent for smaller homes and smaller water demands.

An electric tank water heater takes 60-80 minutes compared to 30 minutes that a gas tank heater takes to heat water.

How Long Does it Take a Tankless Gas Heater To Warm Up?

Tankless water heaters warm up your water “on demand”, so the distance from your heater to the appliance being used is the only consideration which determines how long it will take to receive the hot water out of your faucet.

If the system is working properly, this should not be more than a few seconds with a normal sized home. With a large home, it may take a few more seconds to travel through the water pipes and reach appliances further away from the heater.

A tankless gas heater heats up water instantly so it should only take a few seconds before that hot water travels through your pipes into your fixture.

How Long Does it Take a Tankless Electric Heater To Warm Up?

Just like tankless gas water heaters, tankless electric water heaters only begin to warm up your water once an appliance demands it. In other words, the water is not warmed until you turn on the dishwasher or turn in the faucet.

In most cases, an electric tankless heater will provide hot water within moments, but they can take a tiny bit longer than gas systems, due to the power of gas heat.

A tankless electric heater heats up water instantly so it should also only take a few seconds before the hot water travels through your pipes into your fixture.

Factors That Affect Heat Up Time

In addition to the factors we’ve already explored, such as tank size and BTU rating, there are other circumstances that could dictate how long your water heater takes to warm up water for the first time.

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Incoming Temperature – For both tankless and tank-style water heaters, the temperature that the water starts at will help determine heat up time. Because tank heaters store water and keep them heated, the incoming temperature shouldn’t affect it so greatly. Tankless heaters, however, feed incoming water on demand just moments before it comes out of your faucet. This means that if the groundwater temperature is very low, the water may not get as warm as fast. Both types of heaters can be affected by extremely cold ambient temperatures in the room or area where they are stored. Settings– Although water heaters seem relatively simple when compared with other household mechanicals, they often have more to them. If your heater isn’t working, a professional may need to come to check out any settings or calibration that could be negatively impacting its performance. Age / Maintenance Issues – Just like any other mechanical equipment, your heater’s age and condition could eventually affect its performance, including how long it takes to heat up. A lack of general maintenance, particularly failing to clean up sediment that may be in the pipes could cause performance issues as well. Pipe sediment is more likely in areas with hard water.Distance from Appliance– Sometimes it’s easy for the end user to forget, but your hot water is traveling from the ground, through the heater, and pipes in your home before reaching the appliance you are using. The farther your appliance is from the heater, the longer it could take for the heated water to reach it. A savvy installer should account for this when setting up your system, so it should not be too much of an issue. Pipe Diameter– In addition to the length of piping, the width of your water pipes could affect how long it takes the water heater to heat up. A wider pipe is beneficial as it carries more water, but it will require more water to be heated before the pressure builds enough for it to push through the remaining pipe system.

In summary, there’s a heater perfect for everyone out there. Whether it’s a classic tank or tankless, think about your needs before selecting one.

Now that you know how long it takes both gas and electric water heaters to heat up, see our review of the best models on the market.

With great brands like Bosch, Rheem, and Takagi, you’re sure to find a match!