How Long Does A Water Heater Take To Heat Up (Untold Truth)

automatic green water heater or boiler

If you are like me and countless others, hot showers are some of the most beautiful life luxuries that could be hard to live without. A hot shower soothes like no other and removes the remnants of a long, hard day effectively.

Unfortunately, a faucet does not produce hot water on its own and most people’s electric tankless water heater reviews, including mine, do not create an endless supply of hot water. That would be THE dream!

That said, hot waters can take some amount of time to turn water already far too cold to be enjoyable in the shower unless it is right in the middle of summer and the heat is palpable.

This means any homeowner should know how long to wait when their supply of hot water runs out. I could remember distinctively asking this question when I moved out to my apartment, “How long will it take my water to heat up?” Looking back, it’s not such a dumb question. I do not think people know this information right from the start unless they cared about such stuff when they were younger. Not me.

Here, I will share what I learned about water heaters and how long for the tankless water heater to heat up.

Determine Size and Capacity

Not all water heaters are the same in make and capacity. How long does a new water heater take to heat up may not be like how long it would take an old water heater?

The size of the water heater can also affect the time it takes for water to heat up. The usual size of a water heater is 40 gallons, which is what I have at home, so that is my basis when sharing what I know of about how long for the hot water heater to heat.

The rule of thumb based on what I read and heard is that the bigger the size of the water heater, the longer it can take to heat up the water. An impatient person such as me probably should not get over 40 gallons, unless this is necessary.

Determine the Water Heater

Technician servicing an hot water heaterFew water heater works the same. To know how long for the hot tankless water heater to heat up water, it is crucial to know whether the heater is gas, electric, solar, and tankless. Gas heaters can take at least 30 minutes to 40 minutes to heat the water in the tank fully.

For those with electric heaters, it can take twice as long for the hot tankless water heater to heat compared to using gas heaters. My parents’ home uses electric heaters, and from my experience, it takes at least an hour up to an hour and 20 minutes to heat water. While waiting for the water to heat up, I used to cook breakfast first for my parents. Once done, I will only need a few more minutes to wait before the hot water is ready and I can finally take a bath.

Based on what I know, solar heaters can take as much time as electric heaters to heat water. They can take much longer than gas heaters so they are unnecessary for those who cannot wait. They usually connect solar heaters to an electric water heater, so it is not surprising to note that they can take a relatively similar amount of time to heat up the water.

I never liked solar heaters because not having any hot water if there is no backup energy source on a cloudy day does not appeal to me. It is during cloudy days that I am keen on having hot baths.

If I can have my way, I would rather have a tankless heater. Theoretically, tankless heaters provide the home with an unlimited supply of hot water.

How long for hot water heater to heat up using a tankless heater is next to no warmup time — wow! This could just be the dream water heater come true.

The problem is that it is relatively a new technology so I am sure it will cost an arm and a leg and it may not even be perfect. However, I like never having to wait anymore for the shower to heat up again, so I think I will really look into this more and probably save up.

Compute How Long Does It Take For A Hot Water Heater To Heat Water; It’s Possible!

Since I am sharing how long for a hot water heater to heat up based on my experience and research only, it might not be accurate.

However, there was an article I recently read that provides the specific calculations one can make to know how long does it take for a hot tankless water heater to heat up. I just love Physics and Mathematics that way, they come handy once in a while.

According to Men’s Health, the equation involves finding out how long I want to shower and it leaves how much hot water. Once I have these, I should deduct the minutes of hot water remaining from the expected shower duration, the difference of which I should multiply by 4.3 when I am using an electric heater, or just by 1.9 if I am using gas.

The magazine also asked me to determine the tank’s total minutes of hot water and then deduct the number of minutes the last person used the hot water for.

It provided a chart, showing that 30 gallons in tank capacity mean 19 minutes of hot water in electric heaters and 30 minutes in the gas water heater. If the water heater is at 40 gallons’ tank capacity, this means 25 minutes of hot water in electric heaters and 40 minutes in gas heaters. Last, for water heaters with 50 gallons’ tank capacity, this means having 31 minutes of hot water for electric heaters and 50 in gas heaters.

I tried this method on my parents’ home, where the electric heater capacity is at 30 gallons. When my dad took a hot shower for 15 minutes, I calculated that there would just be four minutes of hot water remaining – not enough for me!

Since I also wanted to loll in my own hot shower for at least 15 minutes, my calculations showed that I needed to wait at least 47 minutes before stepping in. Given that this was nearly an hour, I took the time to eat some breakfast and brush my teeth. Once I got into the shower after 50 minutes, I got some hot water that was relaxing, making me ready for the whole day.

Check for Sediment Buildup!

Technician servicing heating boiler

Sometimes though, I could notice that my water is taking too long to heat. Instead of the usual 30 minutes, I suddenly experienced plunging myself into a cold shower, because the water is not hot yet. I had my gas water heater checked and found out that sediment already has built up in my water heater tank.

The sediment is a mix of dissolved materials like calcium and magnesium that can go into the bottom of the tank and settle there. Overtime, the buildup of sediment can displace the amount of hot water in the tank which can lead to two things. First, it will make the water less available and two, it will take a longer time to heat between refills.

Based on my experience, therefore, finding out how long for the water heater to heat up water is important also as it can show whether the gas water heater is still in mint condition.

It can signal whether the water heater should already be checked and the sediment buildup cleaned out.  Water heaters are in use for a decade and more are already considered old and should be replaced for better performance. How long does a new water heater take to heat up? Faster than a decade-old one!

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