Back to blogs

Find What Size Electric Tankless Water Heater You Need: Our Guide

Choosing the correct size electric tankless water heater is crucial for meeting your hot water demands. An undersized unit may not provide enough hot water, while an oversized unit could waste energy and cost more than necessary. Our guide will help you determine the right size tankless water heater for your needs.

Key Takeaways:

  • Determining the right size tankless water heater is essential for meeting your hot water demands.
  • An undersized unit may not provide enough hot water, while an oversized unit could waste energy and cost more than necessary.
  • Consider factors like flow rate, temperature rise, and the specific needs of your household to determine the correct size tankless water heater needed.
  • Consult with a professional plumbing contractor for accurate sizing and proper installation.
  • Properly sizing your tankless water heater ensures an adequate supply of hot water, eliminates the inconvenience of running out of hot water, and improves energy efficiency.

Understanding Tankless Water Heater Sizing

Tankless water heater sizing is an important consideration when choosing the right unit for your needs. To ensure that you have an adequate supply of hot water while minimizing energy waste, it's crucial to understand the factors that determine the correct size of a tankless water heater.

The two main factors in tankless water heater sizing are the maximum flow rate required by your hot water system and the temperature rise needed. The maximum flow rate is determined by the number of fixtures you use simultaneously and their flow rates. The temperature rise is the difference between the desired set temperature and the temperature of the incoming water.

Factors to Consider in Tankless Water Heater Sizing

In addition to the maximum flow rate and temperature rise, there are other factors that can affect the sizing of a tankless water heater. These include the building supply temperature, pipe sizing, and the number of fixtures in your home. Understanding these factors and their impact on flow volume will help you choose the right size unit for your needs.

To ensure accurate sizing, it's recommended to consult with a professional plumbing contractor who can assess your specific requirements and offer expert advice on selecting the appropriate tankless water heater size.

Tankless Water Heater Sizing Factors Description Maximum Flow Rate The maximum flow rate is determined by the number of fixtures used simultaneously and their individual flow rates. It is crucial to ensure that the tankless water heater can provide enough hot water for your usage needs. Temperature Rise The temperature rise refers to the difference between the desired set temperature and the temperature of the incoming water. This factor is essential in determining the size of the tankless water heater required to meet your hot water demands. Building Supply Temperature The building supply temperature is the temperature of the water entering your home from the main water supply. It can vary depending on the region and time of year. Considering this factor helps determine the appropriate tankless water heater size for your specific location. Pipe Sizing The sizing of the pipes that deliver hot water to your fixtures can affect the flow volume and, consequently, the sizing of the tankless water heater. Proper pipe sizing ensures efficient water delivery and optimal performance of the unit. Number of Fixtures The number of fixtures in your home that require hot water simultaneously is an important consideration when sizing a tankless water heater. It's crucial to ensure that the unit can meet the hot water demand during peak usage periods.

Considering these factors and consulting with a professional will help you accurately determine the right size tankless water heater for your specific needs. The right size unit will provide you with ample hot water while maximizing energy efficiency and cost savings.

How to Find the Correct Size Tankless Water Heater

When it comes to finding the correct size tankless water heater for your home, it's important to consider the required flow rate and temperature rise. These factors will help determine the capacity needed to meet your hot water demands. To simplify the process, you can use an electric tankless water heater capacity calculator provided by manufacturers like Navien's NaviSizer. This tool takes into account specific application details and provides a recommendation based on your needs.

The electric tankless water heater capacity calculator considers factors such as the number of fixtures you typically use simultaneously and their respective flow rates. By inputting this information, the calculator determines the required maximum flow rate to meet your hot water needs. It also considers the desired temperature rise, which is the difference between the desired set temperature and the inlet water temperature. These calculations help ensure you find a tankless water heater that can provide sufficient hot water without wasting energy or costing more than necessary.

Example Calculation:

Let's say you want to determine the correct size tankless water heater for your household's needs. You typically use a shower with a flow rate of 2.5 gallons per minute (GPM) and a kitchen sink with a flow rate of 1.5 GPM. These fixtures are often used simultaneously, so the total required flow rate would be 4 GPM. Additionally, you desire a temperature rise of 60°F, as the inlet water temperature is 50°F and you want a set temperature of 110°F. By using the electric tankless water heater capacity calculator, you can find models that can provide a minimum of 4 GPM at a temperature rise of 60°F to meet your hot water needs.

Fixture Flow Rate (GPM) Shower 2.5 Kitchen Sink 1.5 Total Required Flow Rate 4

Using a tankless water heater size calculator simplifies the process of finding the correct size unit for your home. It ensures that you choose a tankless water heater that can meet your hot water demands efficiently. By considering the required flow rate and temperature rise, you can select a unit that provides sufficient hot water without overspending or wasting energy.

Replacing a Traditional Water Heater with a Tankless Water Heater

When it comes to replacing a traditional water storage heater with a tankless water heater, it's important to note that you can't simply select a tankless size based on tank capacity. Tankless water heaters are measured by hot water flow rate (GPM) instead of storage capacity. To determine the right size tankless water heater for replacement, it is highly recommended to consult with a licensed plumbing professional who can assess your specific needs and explain the differences between tank and tankless models.

By working with a professional, you can ensure that the new tankless water heater will meet your hot water demands efficiently and effectively. A licensed plumber will be able to take into account factors such as the number of fixtures in your home, the flow rate required for simultaneous usage, and the temperature rise needed. These considerations are crucial in determining the appropriate size of the tankless water heater for your specific application.

While it may be tempting to try to determine the size on your own, it's important to remember that improper sizing can lead to issues such as insufficient hot water supply or wasted energy. By relying on the expertise of a plumbing professional, you can rest assured that the replacement tankless water heater will be properly sized and installed, ensuring optimal performance and longevity.

https://www.youtube.com/watch?v=7De7hI7ZXbI

Table: Tankless Water Heater Sizing Guidelines for Replacement

Number of Bathrooms Flow Rate Needed (GPM) 1-2 3.5 2-3 5 3-4 7

Table: Tankless Water Heater Sizing Guidelines for Replacement. This table provides a general guideline for the flow rate needed based on the number of bathrooms in your home. However, it is important to consult with a professional to determine the exact size required for your specific needs.

What Size Tankless Water Heater for Your Household?

Choosing the right size electric tankless water heater is essential to ensure a sufficient supply of hot water for your household. To determine the appropriate size, you need to consider the number of fixtures you typically use simultaneously. Here's a guide to help you determine what size electric tankless water heater you need:

Household Size and GPM Recommendations

For households with 1-2 fixtures used simultaneously, an average flow rate of 3.5 gallons per minute (GPM) is recommended. This is suitable for scenarios like running a shower while using a sink. For households with 2-3 fixtures in simultaneous use, a flow rate of around 5 GPM is recommended. This includes scenarios like running two showers simultaneously. Lastly, households with 3-4 fixtures in simultaneous use should consider a flow rate of approximately 7 GPM. This is suitable for scenarios like running multiple showers and a dishwasher at the same time.

It's important to note that these recommendations serve as a general guideline and can vary based on the specific needs of your household. Factors such as the flow rates of your fixtures and the demand for hot water in your daily routine should also be taken into account.

Consulting a Professional Plumbing Contractor

While this guide provides a starting point, it's always best to consult with a professional plumbing contractor to accurately determine the size of tankless water heater you need. They can assess your specific requirements, consider other influencing factors like pipe sizing and building supply temperature, and ensure that you select the right size to meet your household's demands.

Household Size Simultaneous Fixture Usage Recommended Flow Rate (GPM) 1-2 fixtures Shower and sink 3.5 GPM 2-3 fixtures Two showers 5 GPM 3-4 fixtures Multiple showers and dishwasher 7 GPM

what size electric tankless water heater do I need

By considering the specific needs of your household and consulting with professionals, you can ensure that you select the right size electric tankless water heater to efficiently meet your hot water demands.

Determining Flow Rate and Temperature Rise

To accurately determine the right size tankless water heater for your needs, it's essential to consider the flow rate and temperature rise required. The flow rate refers to the maximum number of devices you want to run simultaneously and their respective flow rates. By adding up the flow rates, you can determine the desired flow rate for the tankless water heater.

Additionally, you need to consider the temperature rise, which is the difference between the desired output temperature and the incoming water temperature. By subtracting the incoming water temperature from the desired output temperature, you can determine the temperature rise needed for your tankless water heater.

For example, let's say you want to run a shower with a flow rate of 2.5 GPM and a desired output temperature of 105°F. If the incoming water temperature is 50°F, the temperature rise would be 55°F (105°F - 50°F). To meet these requirements, you would need a tankless water heater with a flow rate of at least 2.5 GPM and a temperature rise of 55°F.

Flow Rate (GPM) Temperature Rise (°F) Shower 2.5 55 Kitchen Sink 1.5 30 Bathroom Sink 1.0 25

This table provides an example of flow rates and temperature rises for different fixtures. You can use these values as reference points when calculating the flow rate and temperature rise needed for your specific setup.

https://www.youtube.com/watch?v=RLMFrEp7S8k

By determining the flow rate and temperature rise required for your tankless water heater, you can ensure that it meets your hot water demands effectively and efficiently.

Sizing Example

Let's take a look at an example to better understand how to determine the size of an electric tankless water heater. Suppose you want to run two showers simultaneously, each with a flow rate of 2.6 gallons per minute (GPM), and the incoming water temperature is 50°F.

To calculate the size of the tankless water heater you need, you'll need to consider both the flow rate and the temperature rise. In this case, you would require a unit that can produce a flow rate of at least 5.2 GPM (2.6 GPM x 2 showers) and a temperature rise of 55°F (105°F desired output temperature – 50°F incoming water temperature).

Number of Showers Flow Rate per Shower (GPM) Total Flow Rate (GPM) Required Temperature Rise (°F) 2 2.6 5.2 55

In this scenario, a tankless water heater with a minimum flow rate of 5.2 GPM and a temperature rise of 55°F would be suitable to meet your hot water needs. Remember, this is just an example, and the actual size of the tankless water heater you need will depend on your specific requirements and the flow rates of your fixtures.

Proper Water Usage Estimates

When determining the right size tankless water heater for your needs, it's important to estimate your water usage accurately. By considering the flow rates and average water temperatures for various fixtures in your home, you can calculate the total water needs for simultaneous usage. This estimation will help you select the appropriate size tankless water heater.

Below are some typical flow rates for common fixtures as reference points:

  • Shower: approximate flow rate of 2.5 gallons per minute (GPM)
  • Kitchen sink: approximate flow rate of 1.5 GPM
  • Bathroom sink: approximate flow rate of 1 GPM
  • Dishwasher: approximate flow rate of 1.5 to 3.5 GPM
  • Washing machine: approximate flow rate of 2.5 to 3 GPM

These values can vary depending on the specific fixtures in your home, but they serve as a good starting point for estimating your water usage.

Fixture Approximate Flow Rate (GPM) Shower 2.5 Kitchen Sink 1.5 Bathroom Sink 1 Dishwasher 1.5 - 3.5 Washing Machine 2.5 - 3

electric tankless water heater size guide

Example Calculation:

Let's say you have two showers running simultaneously, each with a flow rate of 2.5 GPM. In this case, you'll need a tankless water heater that can provide a total flow rate of at least 5 GPM to ensure an adequate supply of hot water. It's important to consider the simultaneous usage of fixtures in your home to accurately estimate your water needs.

By properly estimating your water usage and selecting the right size tankless water heater, you can ensure a continuous supply of hot water and optimize energy efficiency in your home.

Gas vs. Electric Tankless Water Heater Sizing

When it comes to sizing a tankless water heater, it's essential to consider whether you'll be using a gas or electric model. The type of unit you choose can impact the flow rate and temperature rise capabilities, which directly affect the size of the heater required for your specific needs.

Gas Tankless Water Heater Sizing: Gas-fired tankless water heaters typically offer higher temperature rise capabilities compared to electric models. A gas unit can achieve a temperature rise of up to 70°F at a flow rate of 5 gallons per minute (GPM). This means that if you need hot water for multiple fixtures, such as a shower and a dishwasher running simultaneously, a gas tankless water heater may be the better option.

Electric Tankless Water Heater Sizing: Electric tankless water heaters, on the other hand, may have lower temperature rise capabilities. They can typically provide a temperature rise of around 2°F at a flow rate of 2 GPM. While electric models may not offer the same level of temperature rise as gas units, they can still be suitable for smaller households with lower hot water demand.

Gas Tankless Water Heater Electric Tankless Water Heater Flow Rate Up to 5 GPM Around 2 GPM Temperature Rise Up to 70°F Around 2°F Suitable Applications Simultaneous use of multiple fixtures Smaller households with lower demand

Choosing the Right Size

When sizing your tankless water heater, it's important to consider both the flow rate and temperature rise requirements. Evaluate your hot water needs and determine whether a gas or electric model would be more appropriate for your household.

Keep in mind that sizing a tankless water heater involves various factors, such as the number of fixtures used simultaneously, the desired output temperature, and the incoming water temperature. Consulting with a professional plumbing contractor can help ensure accurate sizing and a proper installation that meets your specific needs.

Other Factors to Consider

When choosing the size of your electric tankless water heater, there are several factors you should consider in addition to flow rate and temperature rise. These factors can have a significant impact on the overall demand and determine the appropriate size of the water heater for your home.

Building Supply Temperature

The temperature of the water entering your home can vary depending on your location and the time of year. In colder climates, the incoming water temperature may be lower, requiring a larger temperature rise to reach the desired output temperature. It's important to factor in the building supply temperature when determining the size of your tankless water heater.

Pipe Sizing

The size and material of the pipes in your home can affect the flow rate and pressure of the water. Smaller pipes or pipes with restrictions can reduce the flow volume, potentially impacting the performance of your tankless water heater. It's essential to consider the size and condition of your pipes when sizing your water heater.

Number of Fixtures

The number of fixtures in your home that require hot water simultaneously is another important consideration. If you have a larger household with multiple bathrooms and appliances that use hot water, you may need a larger tankless water heater to meet the demand. It's crucial to assess the number of fixtures in your home to ensure you choose the right size unit.

Consult with a Professional

Given the various factors involved in determining the size of a tankless water heater, it's recommended to consult with a professional plumbing contractor. They can assess your specific needs, evaluate the factors discussed, and provide expert advice on the appropriate size and installation of your tankless water heater.

Consider these additional factors alongside flow rate and temperature rise to accurately size your electric tankless water heater and ensure optimal performance and efficiency.

https://www.youtube.com/watch?v=UE4I4ZL6f7w

Benefits of Properly Sizing Your Tankless Water Heater

Properly sizing your tankless water heater offers several benefits. When you determine the right size for your electric tankless water heater, you ensure an adequate supply of hot water for your household's needs. No more running out of hot water in the middle of a shower or while doing the dishes. With the right size, you can enjoy uninterrupted hot water on demand.

Not only does proper sizing provide convenience, but it also improves energy efficiency. An undersized unit may struggle to meet your hot water demands, resulting in frequent cycling and energy wastage. On the other hand, an oversized unit may consume more energy than necessary to heat the water, leading to higher operating costs. By choosing the right size, you optimize the performance of your tankless water heater, ensuring it operates efficiently and effectively.

Additionally, properly sizing your tankless water heater allows you to save on operating costs. With an accurately sized unit, you only heat the amount of water you need, eliminating the energy wasted in constantly reheating stored water in traditional tank heaters. This energy-efficient approach can lead to significant savings on your utility bills over time.

Summary:

  • Proper sizing ensures an adequate supply of hot water
  • Improves energy efficiency and reduces operating costs
  • Eliminates the inconvenience of running out of hot water

Benefits of Proper Sizing Your Tankless Water Heater Ensures an adequate supply of hot water Improves energy efficiency and reduces operating costs Eliminates the inconvenience of running out of hot water

The Importance of Professional Installation

When it comes to choosing and installing a tankless water heater, professional assistance is crucial. Proper sizing and installation of the unit are essential for optimal performance and longevity. A licensed plumbing professional can assess your specific needs and guide you through the process, ensuring that you find the right size electric tankless water heater.

Professional plumbers have the expertise to calculate the required flow rate and temperature rise for your household, taking into account factors such as the number of fixtures and the desired output temperature. They can also consider additional factors like pipe sizing and building supply temperature that can influence the overall demand for hot water.

Installing a tankless water heater involves more than just connecting pipes. It requires proper ventilation and electrical connections to ensure safe operation. A professional installer will make sure that all these aspects are taken care of, providing you with peace of mind and a well-functioning unit.

Table: Comparing DIY vs. Professional Installation

DYI Installation Professional Installation Accuracy of Sizing May not account for all factors Accurate sizing based on professional assessment Efficiency May not optimize energy efficiency Proper installation for energy efficiency Safety Risk of improper connections or ventilation Safe installation by a licensed professional Longevity Potential for premature wear and tear Proper installation ensures longevity

So, when it comes to installing a tankless water heater, don't underestimate the importance of professional assistance. A skilled plumber can help you determine the right size tankless water heater, considering all the necessary factors for accurate sizing. They will ensure a safe and efficient installation, allowing you to enjoy hot water on-demand while maximizing energy savings.

Understanding the Limitations of Tankless Water Heaters

While tankless water heaters offer numerous benefits, it is essential to understand their limitations. These units are designed specifically for heating potable (drinking) water and should not be used for pre-heating water or non-potable water applications. By adhering to this limitation, you can ensure that your tankless water heater operates safely and efficiently, providing you with hot water when and where you need it.

When considering the factors to consider when choosing a tankless water heater size, it is important to keep in mind the intended usage. Tankless water heaters are not suitable for heating non-potable water, such as water used for heating pools or other non-drinking water purposes. Attempting to use a tankless water heater for such applications can result in inefficient operation and could potentially lead to damage.

Therefore, when determining the appropriate size for your tankless water heater, it is crucial to consider only the volume and requirements of your potable water needs. This will ensure optimal performance and longevity of your unit, while also maintaining the safety and efficiency of your hot water system.

Limitations of Tankless Water HeatersRecommendationsDesigned for heating potable water onlyUse for drinking water and avoid non-potable water applicationsNot suitable for pre-heating waterUse for on-demand hot water needs onlyMay have limited capacity for simultaneous hot water usageConsider the maximum flow rate and temperature rise to meet your hot water demands

Summary:

  • Tankless water heaters are designed for heating potable (drinking) water only.
  • They should not be used for pre-heating water or non-potable water applications.
  • When choosing a tankless water heater size, consider the maximum flow rate and temperature rise needed to meet your hot water demands.
  • Using a tankless water heater for non-potable water applications can result in inefficient operation and potential damage to the unit.

Conclusion

Choosing the right size electric tankless water heater is crucial for meeting your hot water demands and ensuring energy efficiency. At [Your Company Name], we understand the importance of accurately sizing your tankless water heater to optimize its performance and save on operating costs.

By considering factors like flow rate, temperature rise, and the specific needs of your household, you can determine the correct size tankless water heater needed. Our comprehensive electric tankless water heater size guide provides valuable insights into understanding and determining the appropriate size for your home.

Consulting with a professional plumbing contractor is highly recommended to ensure accurate sizing and proper installation. Our experienced technicians can assess your specific needs, explain the differences between tank and tankless models, and ensure your tankless water heater is correctly installed for optimal performance and longevity.

Don't settle for inadequate hot water supply or unnecessary energy consumption. Trust [Your Company Name] to guide you through the process of selecting the right size electric tankless water heater. Contact us today to ensure your hot water needs are met efficiently and effectively.

FAQ

What factors determine the size of a tankless water heater?

The size of a tankless water heater is determined by the maximum flow rate required and the temperature rise needed. Other factors like building supply temperature and pipe sizing can also affect the flow volume.

How do I find the correct size tankless water heater?

To find the correct size tankless water heater, compare the required flow rate and temperature rise to the specifications of different models. Some manufacturers provide sizing calculators to help determine the right size for your specific application.

Can I replace a traditional water heater with a tankless water heater of the same capacity?

No, tankless water heaters are measured by hot water flow rate (GPM) instead of storage capacity. To determine the right size tankless water heater for replacement, consult with a licensed plumbing professional to assess your specific needs.

How do I determine the size of a tankless water heater for my household?

The average rule of thumb for sizing a tankless water heater is approximately 3.5 GPM for 1-2 fixtures simultaneously, 5 GPM for 2-3 fixtures, and 7 GPM for 3-4 fixtures. However, it's essential to consider the number of fixtures used simultaneously in your household.

How do I calculate the flow rate and temperature rise required for a tankless water heater?

Consider the maximum number of devices you want to run simultaneously and their flow rates. Add up the flow rates to determine the desired flow rate for the tankless water heater. Then, subtract the incoming water temperature from the desired output temperature to determine the temperature rise needed.

Can I use the same sizing guidelines for gas and electric tankless water heaters?

Gas tankless water heaters can typically achieve a larger temperature rise per GPM than electric models. It's important to consider these differences when sizing a tankless water heater based on your specific needs.

Are there other factors to consider when sizing a tankless water hea

Lightning fast quotes.

Our water heater experts are standing by to help. Complete our form or call to schedule service.

Get a quoteA picture of a water heaters now technician.