Properly sizing a tankless water heater is crucial to ensuring that your home has an adequate supply of hot water. A water heater that is too small may not meet the demand, while an oversized heater may be more expensive to operate. To determine the right size, consider factors such as the maximum flow rate required and the temperature rise needed. Navien's NaviSizer tool can help you find the perfect fit for your specific application.
Key Takeaways:
- Sizing a tankless water heater is important for meeting your hot water needs.
- Factors to consider include flow rate, temperature rise, and the number of devices used simultaneously.
- Navien's NaviSizer tool can assist in determining the correct size for your application.
- Gas tankless water heaters have different sizing considerations compared to electric models.
- Consulting with a licensed plumbing professional is recommended for accurate sizing.
How Tankless Water Heater Sizing Works
When it comes to sizing a tankless water heater, two main factors come into play: the maximum flow rate and the temperature rise. The maximum flow rate is determined by the number of fixtures being used simultaneously and their individual flow rates. It's also important to consider the water pipe sizing in your system.
The temperature rise refers to the difference between the desired set temperature and the inlet water temperature. For residential applications, set temperatures are typically around 120 degrees Fahrenheit, while commercial temperatures can vary. The flow rate and temperature rise are then compared to the output of tankless water heaters, which are rated by their gas energy input (BTUs).
To determine the right size for your tankless water heater, you'll need to compare the required flow rate and temperature rise to the specifications of different models. The higher the BTU input, the greater the maximum flow rate the tankless unit can produce. Consider using a sizing tool like Navien's NaviSizer, which takes into account the maximum possible temperature rise and required flow rate to help you choose a unit that meets your needs.
https://www.youtube.com/watch?v=UE4I4ZL6f7w
Factor Description Maximum Flow Rate Determined by the number of fixtures used simultaneously and their individual flow rates Temperature Rise The difference between the desired set temperature and the inlet water temperature Residential Set Temperature Usually around 120 degrees Fahrenheit Commercial Set Temperature Varies Tankless Water Heater Output Rated by gas energy input (BTUs)
Finding Your Tankless Water Heater Size
To find the right size tankless water heater for your home, it's important to compare the required flow rate and temperature rise to the specifications of different models. This will ensure that you choose a unit that meets your needs and provides an adequate supply of hot water. One helpful tool that can assist you in this process is Navien's NaviSizer tool, which takes into account the maximum possible temperature rise and required flow rate to determine the correct size for your application.
Sizing Considerations
When determining the size of a tankless water heater, it's important to consider the maximum flow rate you require and the temperature rise needed. The maximum flow rate is determined by the number of fixtures being used simultaneously and their individual flow rates. The temperature rise is the difference between the desired set temperature and the inlet water temperature. These factors are compared to the output of tankless water heaters, which are rated by their gas energy input (BTUs).
Using the NaviSizer tool, you can input the maximum flow rate and temperature rise required for your application, and the tool will provide you with the appropriate size tankless water heater. This ensures that you choose a unit that can meet your hot water needs without oversizing and wasting energy or undersizing and causing a shortage of hot water.
Choosing the Right Size
By using the NaviSizer tool, you can quickly and easily determine the correct size tankless water heater for your specific needs. The tool takes into account the maximum flow rate and temperature rise, providing you with accurate results in just one minute. This eliminates the guesswork and ensures that you select a tankless water heater that will provide sufficient hot water for your household.
Fixture Flow Rate (GPM) Shower 2.5 Sink Faucet 1.5 Dishwasher 1.0 Washing Machine 2.0
As an example, if you have two showers running simultaneously, you would need a tankless water heater with a flow rate of at least 5 gallons per minute. By considering the flow rates of each fixture you use and comparing them to the maximum flow rate of different tankless water heater models, you can determine the appropriate size for your specific needs.
What Size Tankless Water Heater Replaces Your Tank?
Unlike traditional tank water heaters, tankless water heaters are not measured by tank capacity. Instead, they are rated by hot water flow rate. This means that when replacing your old tank water heater with a tankless unit, you cannot solely rely on tank capacity to determine the appropriate size. Instead, you need to consider the differences in operation and available features.
When choosing the size of a tankless water heater to replace your tank, it is advisable to consult with licensed plumbing professionals. They have the expertise to assess your specific needs and recommend the correct tankless water heater size. Licensed professionals take into account factors such as the number of fixtures in your home, the flow rates of these fixtures, and the temperature rise required to meet your hot water demands.
To ensure a smooth transition from a tank water heater to a tankless unit, it's important to work with professionals who can properly assess your needs and recommend the right replacement size. They can guide you through the process and ensure that you have a reliable supply of hot water without any disruptions to your daily routine.
Fixture Flow Rate (GPM) Shower 1.5 - 2.5 Washing Machine 1.5 - 3 Dishwasher 1 - 2 Kitchen Sink 1.5 - 2.5 Bathroom Sink 0.5 - 1.5
Table: Average Flow Rates for Common Fixtures
What Size Tankless Water Heater for Your Household?
When it comes to determining the right size tankless water heater for your household, there are some general guidelines to consider. These guidelines can help you estimate the required flow rate to meet your hot water needs. Keep in mind that these are rough estimates, and your actual hot water usage may vary based on specific circumstances.
For 1-2 fixtures being used simultaneously, a flow rate of approximately 3.5 gallons per minute (GPM) is typically sufficient. This can include scenarios such as running a shower and a faucet simultaneously.
For households with 2-3 fixtures being used simultaneously, a flow rate of around 5 GPM is recommended. This would accommodate situations like running two showers and a faucet at the same time.
If you have 3-4 fixtures that may be used simultaneously, a flow rate of approximately 7 GPM is needed. This can include scenarios such as running multiple showers, faucets, and appliances simultaneously.
Table: Recommended Flow Rates for Different Household Sizes
Number of Fixtures Simultaneously Used Recommended Flow Rate (GPM) 1-2 3.5 2-3 5.0 3-4 7.0
Remember, these estimates can help you gauge the appropriate size for your tankless water heater. However, it's essential to consider your specific household's hot water usage patterns and consult with a licensed plumbing professional for accurate sizing recommendations.
https://www.youtube.com/watch?v=JYRzO2ve_0A
Tankless Water Heater Sizing Calculator
Choosing the right size tankless water heater for your home is essential to ensure a sufficient supply of hot water. That's why we offer the Navien NaviSizer, a convenient sizing calculator that takes the guesswork out of the process. In just one minute, you can input the necessary information and get accurate results tailored to your specific application.
The NaviSizer considers two critical factors: maximum flow rate and required temperature rise. By knowing how many fixtures you'll be using simultaneously and the desired output temperature, you can determine the appropriate size of tankless water heater for your needs. The calculator then matches your requirements with Navien's comprehensive range of models, ensuring you choose the perfect fit for your home.
Fixture Flow Rate (GPM) Shower 2.5 Kitchen Sink 1.5 Bathroom Sink 0.5 Dishwasher 1.5
For example, let's say you have a combination of fixtures that will be used simultaneously—two showers, a kitchen sink, a bathroom sink, and a dishwasher. Using the flow rates from the table above, you can calculate the total flow rate required for your tankless water heater. With this information, the NaviSizer can determine the appropriate size based on the maximum flow rate and temperature rise needed.
Don't compromise on hot water supply in your home. Use the Navien NaviSizer to accurately size your tankless water heater and enjoy a reliable and efficient solution that meets your hot water demands.
Sizing Tankless Water Heaters: A Step-by-Step Process
When it comes to sizing a tankless water heater, a systematic approach is crucial to ensure you choose the right unit for your needs. By following these step-by-step guidelines, you can accurately determine the size of tankless water heater required for your home.
Step 1: Determine the Maximum Number of Devices
The first step is to identify the maximum number of devices that will be used simultaneously. This includes showers, faucets, dishwashers, and any other appliances that require hot water. Make a list of these devices and their respective flow rates.
Step 2: Calculate the Desired Flow Rate
Next, add up the flow rates of all the devices to determine the desired flow rate for your tankless water heater. This will help you understand the capacity required to meet your household's hot water demands.
Step 3: Determine the Required Temperature Rise
Now, subtract the incoming water temperature from the desired output temperature. This will give you the temperature rise that your tankless water heater needs to achieve. Keep in mind that the incoming water temperature can vary depending on the season and location.
Step 4: Select a Tankless Water Heater
Using the desired flow rate and temperature rise, refer to a tankless water heater size chart or consult with a licensed plumbing professional to select a unit that meets or exceeds your requirements. Consider factors such as energy efficiency, available features, and budget constraints.
By following these steps, you can confidently determine the appropriate size for your tankless water heater, ensuring a continuous supply of hot water for your household.
Table: Tankless Water Heater Sizing Example
Number of Devices Flow Rate (GPM) 2 Showers 5.2 GPM (2.6 GPM each) Kitchen Faucet 1.5 GPM Utility Sink 2.0 GPM
In this example, we want to be able to run two showers simultaneously, along with a kitchen faucet and utility sink. The total flow rate required would be 8.7 GPM. By factoring in the required temperature rise and consulting a sizing chart, you can select a tankless water heater that meets these specifications.
Gas vs. Electric Tankless Water Heater Sizing
When it comes to sizing a tankless water heater, whether gas or electric, there are important factors to consider to ensure you choose the right size for your needs. One key difference between gas and electric tankless water heaters is the temperature rise per gallon per minute (GPM) they can achieve.
Gas-fired tankless water heaters generally have a higher temperature rise compared to electric models. Gas units can typically achieve a temperature rise of 70°F at a flow rate of 5 GPM, while electric units usually reach a temperature rise of 70°F at a flow rate of 2 GPM. This difference in temperature rise per GPM should be taken into account when sizing a tankless water heater to ensure it can meet your hot water needs.
Another consideration is the flexibility in adjusting flow rates and temperature rise. Gas-powered tankless water heaters generally offer more flexibility in this regard, allowing you to fine-tune the system to meet your specific requirements. Electric tankless water heaters may have limitations in terms of adjusting flow rates and temperature rise. Consulting with a licensed plumbing professional can help you determine the right size and type of tankless water heater, considering factors such as gas vs. electric and specific usage needs.
Tankless Water Heater Type Temperature Rise (at 70°F) Flow Rate (at 70°F) Gas 70°F 5 GPM Electric 70°F 2 GPM
https://www.youtube.com/watch?v=O3sTs7d3cgk
Choosing the right size tankless water heater, whether gas or electric, is crucial for meeting your hot water demands efficiently. By considering factors like temperature rise and flow rate, and understanding the differences between gas and electric models, you can make an informed decision that ensures a reliable and consistent supply of hot water for your home.
Other Factors to Consider in Tankless Water Heater Sizing
When sizing a tankless water heater, there are several additional factors to take into consideration beyond flow rate and temperature rise. These factors can play a significant role in determining the best size and type of water heater for your specific needs.
Water Temperature at the Farthest Faucet
One important factor to consider is the potential for a decrease in water temperature at the farthest faucet in your home. If you have a large or complex plumbing system, or if you frequently use fixtures that are far from your water heater, you may experience a drop in temperature. This could be particularly noticeable if you have a high flow rate or if the incoming water temperature is already on the cooler side.
To mitigate this issue, it is recommended to consult with a licensed plumbing professional who can assess your specific situation and recommend the appropriate size and type of tankless water heater to ensure consistent hot water temperatures throughout your home.
Flexibility of Gas vs. Electric Units
Another factor to consider is the flexibility offered by gas-powered units compared to electric models. Gas tankless water heaters generally offer more options for adjusting flow rates and temperature rise, which can be advantageous in tailoring the system to your specific hot water needs. Electric units, on the other hand, may have more limitations in terms of achieving higher flow rates and temperature rises.
In summary, when considering the size of your tankless water heater, it is essential to account for factors such as the potential for decreased water temperature at far faucets and the flexibility offered by different types of units. By taking these factors into consideration in addition to flow rate and temperature rise, you can ensure that you select a tankless water heater that meets your specific hot water needs.
Tankless Water Heater Sizing Chart for Various Fixtures
When determining the size of a tankless water heater for your home, it's essential to consider the water usage and temperature requirements of various fixtures. The chart below provides a range of water usage and average water temperatures for common fixtures. This chart can serve as a helpful reference point when determining your total simultaneous water needs.
Fixture Usage (GPM) Average Water Temperature (°F) Shower 2.1-2.6 105-120 Kitchen Sink 1.0-1.5 105-120 Bathroom Sink 0.5-1.0 105-120 Dishwasher 1.0-3.0 120 Washing Machine 1.5-2.5 120
For example, if you anticipate running two showers simultaneously, each with an average water usage of 2.6 GPM and a desired water temperature of 120°F, you would need a tankless water heater that can deliver a flow rate of at least 5.2 GPM and achieve a temperature rise of 55°F. Using this sizing chart, you can estimate your hot water needs based on the fixtures you plan to use concurrently.
It's important to note that the chart provides average usage and temperature values, and actual hot water needs may vary depending on specific household requirements. Consulting with a licensed plumbing professional or using a sizing calculator, such as Navien's NaviSizer, can help ensure accurate sizing for your tankless water heater. By taking into account the simultaneous usage of fixtures and desired water temperatures, you can select a tankless water heater that meets your household's hot water demands.
Sizing Example for Tankless Water Heaters
Let's take a practical example to understand how to determine the right size for a tankless water heater. Suppose you want to run two showers simultaneously, and the incoming water temperature is 40°F. Each shower uses 2.6 gallons of water per minute. To calculate the required tankless water heater size, we need to consider the flow rate and temperature rise.
First, determine the total flow rate by adding up the flow rates of the two showers. In this case, the total flow rate is 5.2 gallons per minute (2.6 GPM + 2.6 GPM = 5.2 GPM). Next, calculate the required temperature rise by subtracting the incoming water temperature from the desired output temperature. Assuming the desired output temperature is 120°F, the temperature rise is 80°F (120°F - 40°F = 80°F).
Based on these calculations, you would need a tankless water heater that can deliver a flow rate of at least 5.2 gallons per minute with a temperature rise of 80°F. Consult a tankless water heater size chart or use tools like Navien's NaviSizer to find the exact model that meets these requirements. Remember that sizing may vary depending on factors such as fixture types, usage patterns, and geographical location.
Table: Tankless Water Heater Size Calculation
Fixture Flow Rate (GPM) Shower 1 2.6 Shower 2 2.6 Total Flow Rate5.2
In this sizing example, we have determined that a tankless water heater with a minimum flow rate of 5.2 gallons per minute and a temperature rise of 80°F would be suitable for running two showers simultaneously with an incoming water temperature of 40°F. Remember to consider your specific needs and consult with professionals for accurate sizing recommendations.
Conclusion
Sizing a tankless water heater is crucial to ensure you have the right capacity for your hot water needs. By considering factors such as flow rate, temperature rise, and the maximum number of devices being used simultaneously, you can find the perfect size for your home. Whether you're in need of tankless water heater sizes for residential or commercial applications, it's important to select a unit that meets your specific requirements.
Tools like Navien's NaviSizer can assist you in determining the correct size for your tankless water heater. By inputting information about your application, you can quickly find the optimal fit. Alternatively, consulting with a licensed plumbing professional can provide expert guidance tailored to your unique needs.
With the right-sized tankless water heater, you can enjoy an efficient and reliable supply of hot water in your home. Don't settle for inadequate water heating—make sure you have the appropriate tankless hot water heater dimensions to meet your demands.
FAQ
How do I determine the right size tankless water heater for my home?
The size of a tankless water heater is determined by factors such as the maximum flow rate required and the temperature rise needed. Consider using tools like Navien's NaviSizer or consult with a licensed plumbing professional to accurately determine the right size for your specific needs.
How are tankless water heaters sized?
Tankless water heaters are sized based on the maximum flow rate and temperature rise required. The flow rate is determined by the number of fixtures being used simultaneously and their individual flow rates, while the temperature rise is the difference between the desired set temperature and the inlet water temperature.
Can I replace a traditional water storage heater with a tankless water heater of the same tank capacity?
No, tankless water heaters are not measured by tank capacity like traditional water storage heaters. It is important to consult with a licensed plumbing professional to determine the correct tankless water heater size when replacing a tank, taking into account the differences in operation and available features.
What are the general guidelines for sizing a tankless water heater for a household?
Rough estimates for sizing a tankless water heater are as follows:- For 1-2 fixtures simultaneously, a flow rate of 3.5 GPM is typically sufficient.- For 2-3 fixtures simultaneously, 5 GPM is recommended.- For 3-4 fixtures simultaneously, 7 GPM is needed.These estimates may vary based on your specific household's hot water usage.
How can Navien's NaviSizer tool help with sizing a tankless water heater?
Navien's NaviSizer tool is a convenient sizing calculator that takes into account the maximum possible temperature rise and required flow rate. By inputting information about your specific application, you can quickly determine the correct size tankless water heater you need.
What are the differences in sizing between gas and electric tankless water heaters?
Gas tankless water heaters generally have a larger temperature rise per gallon per minute (GPM) than electric models. Gas units can typically achieve a larger temperature rise at a given flow rate compared to electric units. It's important to consider this when sizing a tankless water heater to ensure it meets your hot water needs.
What other factors should I consider when sizing a tankless water heater?
In addition to flow rate and temperature rise, factors such as faster flow rates or cooler inlet temperatures can affect the water temperature at the farthest faucet. Gas-powered units generally offer more flexibility in adjusting flow rates and temperature rise. Consulting with a licensed plumbing professional is recommended to determine the best size and type of tankless water heater for your specific needs.
Is there a sizing chart available for different fixtures?
Yes, a sizing chart can be used as a reference point when determining your total simultaneous water needs. It can help you estimate the required flow rates for common fixtures when sizing a tankless water heater.
Can you provide an example of how to calculate the size of a tankless water heater?
Let's say you want to be able to run two showers simultaneously, and your incoming water temperature is 40°F. Assuming each shower uses 2.6 gallons of water per minute, you would need a tankless water heater that can produce a temperature rise of at least 55°F while delivering a flow rate of 5.2 gallons per minute.
