Electric Tankless Water Heater Sizing Calculator 2023

Last updated on August 28th, 2023

Have you ever installed a tankless water heater and wondered what size will work best for your home? You’re not alone. I’ve built my fair share of electric tankless water heaters and have learned the ins and outs of sizing these beasts. This has led me to create my own Electric Tankless Water Heater Sizing Calculator to gauge the necessary size for your application based on your usage needs.

Most people don’t know how to determine an electric tankless water heater size. It’s a pretty simple formula, however. In this post, we’ll show you how you can figure out the right equipment to properly heat your water without the use of traditional storage water tanks.

But if you understand how they work and have a few savvy installer tips in your back pocket, you can make sure you don’t get overcharged for electrical service or under-satisfied with your home hot water performance. Continue reading the article to know about it properly. 

What Size Tankless Water Heater Do I Need?

The size of your tankless water heater is determined by the amount of hot water that you need. The larger the family, the more hot water they use, and the larger tankless water heater you need.

Standard tankless water heaters are available in sizes ranging from 1/2 to 4 gallons per minute (GPM). Here are some common tankless water heater sizes:

1/2 GPM: This type can heat up to 5 gallons of water per minute. It is ideal for a one-bedroom apartment or a studio apartment. It is also good for small homes with one bathroom and one shower. 

The unit can be installed on an exterior wall or inside an attic or crawlspace. It works best if it is installed near the shower or sink where it will be used most often, but it can be installed anywhere within 50 feet of a cold water source and the electrical outlet.

3/4 GPM: This type can heat up to 8 gallons of water per minute and should be used in homes with two bathrooms and two showers that are used frequently throughout the day (for example, if there are children in the house). It is also good for small businesses that have multiple employees using bathrooms.

When choosing your tankless water heater, the first step is to determine the volume of hot water you need. This is important because it helps you choose the right size for your home.

• The second step is to figure out how much energy you want to use throughout the day.
• Once you know these two things, it’s easy to find a system that suits your needs.
• Tankless water heaters are available in a wide variety of sizes, from as small as 20 gallons per minute (gpm) up to 32 gpm and more. But if you only need a little bit of hot water, then this may not be necessary. You can opt for a smaller tankless system with less power than what you might think you need.
• For example, if your family uses 2 gpm on average, then you can probably get by with a 10-12 gpm tankless water heater. A 20-gallon per minute unit will provide enough hot water for most families and even some commercial applications like laundromats or restaurants that don’t have large volume requirements.

Overview: Electric Tankless Water Heater Sizing Calculator

Tankless water heater sizing is a relatively simple process. When you’re buying a tankless water heater, you need to know how many people will be using the hot water and how much hot water they will use at once. You also need to know the flow rate of your existing plumbing system, which is typically listed in gallons per minute (GPM).

1. Flow Rate (GPM): 

A flow rate of 1.5 GPM should be used as a starting point for tankless water heater sizing. If you have a large family or are planning to use your tankless system for multiple purposes, such as washing dishes, clothes and showering at the same time, then increase this number by 50%.

2. Temperature Rise (ΔT):

The temperature rise of your tankless system is determined by its efficiency rating. The higher the efficiency rating, the lower the temperature rise will be. The following chart shows some common efficiency ratings:

• Efficiency Rating Temperature Rise (%)
• 80% 6-7 degrees F (3-4 degrees C)
• 82% 5 degrees F (2.8 degrees C)
• 84% 4 degrees F (2.2 degrees C)

How to Calculate the Total Flow Rate Your Home Needs?

The flow rate of your home’s plumbing system is the volume of water that flows through the pipes in a unit of time. It is measured in gallons per minute (GPM).

When calculating the total flow rate of your plumbing system, it is important to account for all of the fixtures and appliances in your home. This includes sinks, showers and toilets. If you have a large family or many guests, then you may need a larger total flow rate than someone who lives alone.

In most cases, there are 6 ways to calculate your home’s total flow rate:

1. Flow Meter Method

Use this method if you have an existing water meter or pay for your water usage by meter reading. The utility company measures how much water flows through the meter in a given period of time (usually one month). They then report this number on your bill every month. You can use this number as an estimate for how much water will flow through your pipes at any given moment if all faucets were opened simultaneously.

2. Drainage Method

This method is based on simple math and allows you to calculate how much water will flow through your home over a period of time. To do this, you need to know the size of your home and its square footage, as well as the amount of time that it takes to fill up a 5-gallon bucket with water (a standard unit of measurement).

3. Runoff Method

This method uses a bit more complicated math and requires that you have access to some specialized software. The runoff method calculates how much water will flow through your home based on rainfall data within a specific area. You can find these data sets online or use them if they are provided by local agencies like the National Weather Service or your local municipality.

4. Pressure Drop Method

The pressure drop method involves calculating the pressure drop through each segment of piping in your plumbing system. The pressure at the point where water enters a pipe is measured in pounds per square inch (PSI), while the pressure at the point where water exits a pipe is measured in PSI drop (distance between points of entry and exit).

5. The Hydraulic Jump Method

The Hydraulic Jump Method also uses a pressure gauge to determine how much air your home needs, but it isn’t as accurate as the Pressure Drop Method because it doesn’t take into account wind speed or temperature differences between indoor and outdoor air temperatures. It works best when there are no obstructions between the indoor and outdoor units like trees or buildings.

6. The Venturi Tube Method

The Venturi Tube Method is another way to calculate total flow rate using a pressure gauge and airflow measurements from an open venturi tube (chimney). This method only works for residential heating applications, so it isn’t very helpful for cooling systems that have vents in other parts of your home like kitchens and bathrooms.

Electric Tankless Water Heater Sizing Calculator Review

Electric tankless water heaters are a popular choice for home owners. They are smaller, easier to install and use less energy than a traditional tanked water heater. But how do you know which one is right for you?

The best way to determine the size of your electric tankless water heater is by using an online calculator. These calculators help determine how much hot water you need, based on the size of your home and what appliances you plan to use. When shopping for an electric tankless water heater, be sure to look at the recommended sizing calculations before making a purchase.

The problem with most tankless water heaters is that they don’t have enough power to run all the time. This means that you’ll never get your shower hot enough or get enough hot water for washing dishes or doing laundry.

Read Also: 8 Best Electric Tankless Water Heaters

This calculator helps you find out how much power your tankless water heater needs in order to run at full capacity all day long. You just plug in your average daily usage numbers, along with some other factors, and it will tell you exactly how much power you need from your electric tankless water heater.

There are many different kinds of tankless water heaters available on the market today, but this one seems to be the best choice for most people who need an electric tankless water heater for their home or business. 

The reason why this model is so popular is because it works well for almost any situation where there isn’t an existing gas line available for installing a traditional tank-style hot water heater.

In addition, this model uses very little electricity compared to other models on the market today because it doesn’t have any moving parts inside the filter. 

Features: Electric Tankless Water Heater

Electric tankless water heaters come in a variety of sizes to meet the needs of your home. The best size for you depends on the number of people who will be using hot water in your home and how often they use it.

Run Time: Electric Tankless Water Heater Sizing Calculator

The run time is the length of time that a tankless water heater can run without needing to be refueled or recharged by an electrician. The average residential tankless water heater has a run time between 5 and 20 minutes, depending on the size and manufacturer.

Gallons per Minute (GPM)

The GPM is the amount of hot water that can be produced by the unit at one time, which is important when deciding whether you need a large or small model for your home. 

For example, if you have only one bathroom with low flow fixtures, then a small unit may suffice, but if you have several bathrooms and all with high flow fixtures then you will need more capacity from your hot water tankless system. Tankless units vary widely in GPM output; for example some units produce 2 GPM while others produce up to 6 GPM.

Instant Supply

The instant supply feature allows users to have unlimited hot water at their fingertips without having to wait for storage tanks to fill up. When you turn on your faucet, hot water will come out instantly without having to wait for it to heat up inside the tank. You can also use this feature when showering or washing dishes because it provides endless hot water instantly.

Endless Hot Water

If you have ever had an electric hot water heater before, then you know how difficult it is to get enough hot water when everyone in the house wants to shower at once or wash dishes at the same time. With a tankless water heater, you will never run out of hot water again because its endless supply means that everyone in your home will always get enough warm water whenever they need it!

Digital Proportional Flow Control

This feature automatically adjusts the amount of gas being used by the unit based on how much water is being used at any given time. It can also reduce energy usage when there is less demand for hot water, like at night when everyone is sleeping. This feature helps keep your energy bills low while providing consistent hot water throughout the day and night!

Low Installation Cost

Tankless water heaters are much less expensive to install than traditional storage tank systems because they have fewer parts and don’t require an extra-large storage tank. This also means that they’re easier to repair if something goes wrong with them down the line.

Compact Design: Electric Tankless Water Heater Sizing Calculator

Another feature that makes this calculator stand out from others on the market is its compact design. This may not seem like a big deal at first glance, but it actually makes a huge difference when it comes to installation and maintenance costs. 

The reason for this is because compact designs are easier to install than larger ones — particularly when working with older homes or smaller spaces like apartments and condos with limited space around their plumbing systems. 

The calculator is straightforward to use

The calculator will provide you with a perfect water heater for your home. It also provides you with a detailed report that shows how many gallons of hot water you need to have at all times. You can download the report and share it with your plumber or contractor. The detailed report will help them install the right tankless water heater for your home.

It offers a complete sizing solution

If you are looking for an efficient option that will save money on water heating bills, then this is the right choice for you. The electric tankless water heaters are available in a wide range of sizes so that they can meet different needs of homeowners. They are also easy to install and use, which makes them perfect for homes with small children and pets who can accidentally pull them down if they are not properly installed or maintained.

You can get a quick estimate in just seconds

You can get a quick estimate in just seconds with this easy-to-use tool. It has a slider control for peak flow rate settings so you can customize it based on how much hot water you need at one time. This calculator also gives you an estimate of how much money it will save each year compared with other types of hot water heaters (such as gas or propane).

It has a slider control for peak flow rate settings

You can get a quick estimate in just seconds by using this calculator. It has a slider control for peak flow rate settings, so it will ensure that you are getting the right size of tankless water heater for your needs.

The electric tankless water heater sizing calculator is easy to use and very accurate. It will give you an estimated cost as well as the estimated power usage, which makes it easy to compare different models and find one that fits your needs best.

Why Should You Use this Calculator?

We’ve had many customers tell us that they love our online tool because it saves them time and money. It gives them an accurate idea of what size of tankless water heater they need without having to spend hours researching online or calling a professional.

Our calculator also has a slider control for peak flow rate settings so you can see how much hot water you’ll really need at different times of the day. If you have large families or guests visiting often, this feature will help prevent over-heating your home or business by choosing a larger model than necessary.

Conclusion: Electric tankless water heater sizing calculator 

If you look around today, it is easy to see that many homeowners are making the decision to install tankless water heaters. There are several reasons for this, but one of the largest is that they can cut energy bills by as much as half. It is a great way for homeowners to save money, and save on monthly utility bills.

Electric water heating tankless water heater is the natural gas tankless water tank. Now using this type of tankless water heater is more popular because the price is not expensive and there are models of high-pressure loss.