Solved! How to Select the Right Water Heater Size
Despite the fact that you may not think about it very often, you use your hot water heater on a regular basis. Providing hot water whenever you need it is the one item that helps keep things clean and operating smoothly in every household. The question is, how do you determine the proper size tankless water heater for your household? Consider how many appliances you will be using at the same time. For example, if two persons living in an average-sized home need to shower every day at different times of the day (for example, because they work opposing shifts), a 2 GPM model would be plenty.
HomeInspectionInsider.com makes no representations as to the suitability of the information it publishes.
It is owned and operated by Hubert Miles who is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by placing advertisements and links on their websites that direct traffic to Amazon.com (hereinafter referred to as “Amazon.com” or “Amazon.com Associates Program.”).
Hubert Miles receives a commission for recommending visitors and business to these businesses.
For a tank-style heater, household size is a simple indicator of hot water needs.
Based on the number of people living in the residence, you may estimate the required tank capacity (in gallons) as follows:
- For one or two people, 23 to 36 gallons are needed, for two to four people, 36 to 46 gallons are needed, and for three to five people, 46 to 56 gallons are needed
- For five or more people, more than 56 gallons are needed (add 10 gallons for each extra person).
A 40-gallon water heater, such as A. O. Smith’s ProLine Power Vent Gas Water Heater (available from SupplyHouse), should be sufficient for the average household of four. However, it should not be your only factor to consider. It is possible to obtain a more realistic picture of your family’s hot water requirements by delving a bit further.
In addition to tank capacity, consider a water heater’s first hour rating.
A 40-gallon water heater, such as A. O. Smith’s ProLine Power Vent Gas Water Heater (available from SupplyHouse), should be sufficient for the needs of the average household of four people. The cost should be considered, but it should not be the only factor to consider. Investigating your family’s hot water requirements in greater depth will provide you with more accurate results.
- Bathing or showering (per person) requires 20 gallons
- Washing hair (per person) requires 6 gallons
- Washing hands (per person) requires 2 gallons
- Washing dishes by hand requires 6 gallons
- Shaving requires 3 gallons
- Running the dishwasher requires 14 gallons
- Running the clothes washer requires 30 gallons.
Consult with a professional Find qualified plumbing professionals in your area and receive free, no-obligation estimates for your plumbing project on HomeAdvisor. +Image courtesy of supplyhouse.com
If a larger tank won’t fit in the existing space, consider a tankless heater.
Tankless heaters, which are often wall-mounted, are able to fit into smaller spaces since they do not require a large storage tank, as O’Brian points out. Typical tank water heaters may be up to six feet tall and 22 inches in diameter, with a capacity of 50 gallons. An alternative tankless water heater with equivalent power, for example, the Takagi Tankless Natural Gas Water Heater (available from SupplyHouse), is just 20 inches high, 14 inches wide, and less than 10 inches deep, making it an ideal choice for small spaces.
If you have a limited amount of available space, a tankless water heater may be the best option. Image courtesy of istockphoto.com
To select the right tankless water heater, estimate the necessary flow rate based on hot water usage and the required change in temperature.
Tankless water heaters do not have a storage tank to hold hot water. Instead, they heat it only when it is required. “Flow rate is the most important factor to consider when sizing a tankless water heater,” O’Brian explains. The following information will assist you in estimating the flow rate requirements for your family.
- To begin, figure out how much hot water you use during peak hours. Peak consumption is defined as the period of time during which you consume the largest amount of hot water. In order to compute the maximum amount of hot water you would consume at one time, consider the following list of typical flow rates (per fixture) in gallons-per-minute (gpm)
- Water flow rates for sink faucet: 1 gpm
- Bathtub: 3 gpm
- Shower: 2.5 gpm
- Dishwasher: 3 gpm
- Clothes washer: 3 gpm
- 1.25 gallons per minute (gpm) for the sink faucet
- 3.25 for the bathtub and shower
- 3.25 for the dishwasher and 3.25 for the laundry.
Check out this video from SupplyHouse on how to properly size tankless water heaters for a more visual explanation. It is with great pleasure that SupplyHouse.com brings you this article. BobVila.com is the source of the information and viewpoints presented. Consult with a professional Identify qualified plumbing professionals in your area and receive free, no-obligation quotes for your plumbing project.+
What Size Water Heater Do I Need?
That is an excellent question. What is the solution? It is necessary to determine how much hot water you use on a regular basis during your busiest “hot-water-using” hour in order to receive an accurate response. However, if you simply want a rough estimate of the size you require (as opposed to a precise calculation), follow these guidelines:
- 30-40 gallons for one to two people
- 40-50 gallons for two to three people
- 50-60 gallons for three to four people
- 60-80 gallons for five or more people
We’ll explain why the numbers in the table above are only “rough estimates” and why they may not be precise enough to satisfy your hot water requirements. We’ll also demonstrate how to calculate the precise water heater size that will fulfill your requirements (and saves you money). Please be advised that this essay will focus on the size of tank water heaters. Interested in a tankless water heater but not sure what size to get? Check out our blog on tankless water heater sizes for some guidance.
Simply get in touch with us and we’ll take care of everything.
Only need a loose estimate for now? Start here…
Homeowners may simply require a general understanding of water heater dimensions in order to obtain a better sense of how much their water heater installation will cost in order to budget accordingly. Prediction: the size of your water heater has a direct relationship with the cost of running it; the “larger” your water heater, the more expensive it is to run it. Depending on how many people live in your household, you may estimate the size of the dumpster you’ll need (see below). Please keep in mind that the values in this table are intended to be used as very broad guides only, and they may not exactly reflect your hot water requirements.
As you can see, the size of the tank you require is entirely dependent on your hot water use patterns.
In contrast, if you only seldom use more than one hot water device at the same time, you may only want a considerably smaller tank. That being stated, before purchasing a water heater, you should be certain that the tank capacity is appropriate for your needs. The reason behind this is as follows:
- Inadequate hot water due to a water heater that is too small may result in never having enough hot water, and/or a water heater that is overworked, resulting in frequent repairs or early collapse. A water heater that is overly large may result in higher-than-necessary energy expenditures (since it is heating water that is not being used)
Are you ready to find out what size water heater you require? Take a look at this.
Want to know the exact size water heater you need? Do this.
Are you ready to find out what size water heater you require? Click here to discover more. Click here to continue reading.
2. Use the chart below to add up the gallons of hot water you need during this hour.
You should consider all of the hot water activities that you would ordinarily fit into that specific hour once you’ve identified which hour is your busiest hour. To determine your approximate peak hour usage for electricity, utilize the chart below. Source
3. Find a water heater that has a “first hour rating” within 1-2 gallons of your peak hour demand.
Every water heater is equipped with an FHR (first hour rating). Using a full tank of hot water as a starting point, this number represents the amount of gallons of hot water the unit can supply in a single hour of operation. So, in general, if your FHR and peak hour demand are in sync, your water heater will provide enough hot water to suit your demands. If you are on a manufacturer’s website, you may discover the FHR of a water heater in the “specifications,” “features,” or “performance” sections of the water heater (see below).
It will be referred to as the “Capacity (first hour rating)” in the report.
Need help from a Florida plumber?
Simply get in touch with us. Upon request, we will provide you with a free estimate in which we will determine the precise tank size you require. We’ve been providing high-quality water heater installations in Florida for more than 50 years, and every one of them is guaranteed by our 100 percent satisfaction guarantee! View a map of our service area in Florida.
Related reading:
- Should I Repair or Replace My Water Heater
- Should I Repair or Replace My Water Heater
- Should I Replace My Water Heater There are three things to keep in mind:
Sizing Guide: What Size Water Heater Do I Need for My Home?
Whether I should repair or replace my old water heater is a question I’ve been wrestling with for a long time. Consider the following three factors:
Water Heater Sizes
What size water heater do you require to meet the needs of your household? If you have a large number of children, the answer to this question will be different for each one. For example, a household of three to four people should acquire a water heater that holds 50 to 60 gallons. A home of 5 to 7 people, on the other hand, may require a water heater with a 60 to 80 gallon water tank. An 80 gallon water heater will offer you with adequate hot water to shower, do laundry, and wash dishes if you live alone with your spouse.
The size of your water heater will be determined by a variety of factors, including the number of people in your household and the length of time you spend in the shower on average.
Hot Water Usage Habits
Is it necessary to purchase a larger water heater to fit your entire family? If you have a large number of children, the answer to this question will be different. Purchasing a water heater for a household of three to four people, for example, is a good investment. When a household of 5 to 7 people is involved, a water heater with a 60 to 80 gallon water tank may be necessary. An 80 gallon water heater will offer you with adequate hot water to shower, do laundry, and wash dishes if you live alone or with your spouse.
These are only approximate measurements for your home’s interior space. Several factors, such as the number of people in your household and the length of time you spend showering, will determine how large your water heater should be.
How to Determine How Much Water You Use
While the estimations provided above can be used to get an approximate idea of the amount of water heater you will want, there is a more exact technique of determining the size of a water heater. First and foremost, you must examine your water use patterns in order to estimate your peak water consumption hour. If your family showers from 8:00 a.m. to 9:00 a.m. every morning, this is the time of day when you use the most water. You’ll need to figure out how many gallons of water you use throughout this period of the day to be accurate.
- If there are a total of 5 people in your household who shower in the morning, you should multiply 10 gallons by the total number of water usage sessions, which is 5.
- This means that a family of five would consume 50 gallons of water each morning from 8:00 a.m.
- However, it is probable that you will consume more than 50 gallons of water to wash the dishes from your meal.
- Your total water use will be equivalent to 56 gallons once you have finished washing your dishes, assuming that each member of your household takes a shower.
- 63 gallons of water have been consumed by your family after everyone has done bathing, cleaning dishes, and doing laundry.
- The First Hour Rating (FHR) of a water heater should be more than the entire volume of water consumed during your highest water usage hour, which you should look for while comparing different water heater sizes at the store while shopping.
- This rating may be obtained on the website of the manufacturer.
- It will be situated at the top of this sticker on your water heater, and it will read “FHR Rating.” More information may be found at: Reasons Why It’s Critical to Replace Your Lead Pipes
Other Factors to Consider While Sizing Water Heaters
The size of your water heater may be increased if one or more persons in your household choose to take a bath in the morning instead of showering. A basic little bathtub has a capacity of 40 gallons of water on average, which is plenty for most people. A huge bathtub, on the other hand, may be able to accommodate up to 140 gallons of water. We propose that you have your children reuse the same bathwater in order to save money on your water costs. If you choose to acquire a tankless water heater rather than a typical water tank, you will be required to follow a new set of rules when determining the appropriate size for your water heater.
- The Flow Rate and Temperature Rise should be calculated in order to establish the size of the tankless water heater that you will require.
- Giant gallons are used to measure the entire volume of water.
- If you want assistance in determining the appropriate size water heater for your home, please contact our staff at (484) 206-8594.
- Additionally, we offer a variety of other services such as water line installation, air conditioning tune-ups, furnace repairs, and drain cleaning, among others.
In addition to West Chester, Broomall, Coatesville, and Conshohocken, WM Henderson provides plumbing and HVAC services across Pennsylvania. Since 1977, we’ve been offering trustworthy plumbing, heating, and air conditioning services to people of the Commonwealth of Pennsylvania.
Hot Water Heater Buying Guide
Taking a cold shower or paying high energy bills are not something anyone wants to do. Hot water heaters are important because they provide cost-effective and dependable hot water for your household.
Purchasing a Water Heater
Whether you’ve just experienced your first unexpectedly chilly shower or just want to lower your energy bills, investing in a new hot water tank is a wise decision. Follow these procedures to avoid having to guess about your appliance’s operation and fix problems:
- Determine the source of the fuel
- Select the type of heater you want
- Find out how much capacity you have
- Take a measurement of the space
Water Heater Fuel Sources
To begin, identify the sort of fuel source that is currently in use in your home. The following table summarizes the distinctions between electric, gas/propane, and hybrid fuel types.
Electric Hot Water Tanks:
- To heat water, one or two interchangeable heating components should be used. Compared to other sorts, it is less costly. There is a wide range of high-efficiency alternatives available
- Sizes range from 28 to more than 100 gallons.
- It is necessary to use a burner to heat the water
- It also requires flowing air around it. It is not possible to keep flammable items near by
- Water heaters that use gas are more costly than electric water heaters. Water heaters that use less energy than electric water heaters
- Sizes ranging from 30 to 100 gallons are available.
- Make use of the energy in the air to heat the water
- It is possible to utilize either outside air or air from the room where it is being kept. Water tanks are available as built-in units or as add-ons to existing tanks. Electric water heaters that are larger than conventional models
- An early investment that is more expensive
- It is more energy efficient, which results in cheaper utility expenses. Sizes available range from 50 to 80 gallons.
Types of Water Heaters
When selecting a water heater, take into account the size of your household as well as the availability of utilities in your location.
Storage Tank
This is the most often seen form of water heater. They feature an insulated tank where water is heated and kept until it is required. They are available in three different fuel types: electric, liquid propane, and natural gas. Water heaters powered by natural gas or propane often consume less energy and are less expensive in operation than electric versions of the same size. When purchasing a water heater, it is important to consider its energy efficiency as well as its annual operating expenses.
- Tankless water heaters do not have a storage tank for hot water.
- Because a tankless water heater simply warms water as it is consumed, it is often more energy efficient than a standard storage tank water heater because it is not required to keep unneeded water hot.
- A tankless water heater can only deliver a limited amount of hot water at a given time.
- These units are a fantastic solution for anyone whose needs do not generally require hot water from more than two sources at the same time.
- Utility water heaters are often available in capacities ranging from 2.5 to 19 gallons.
- Water heaters for mobile homes are available.
- All heaters must be certified by the Department of Housing and Urban Development (HUD).
- Electric heaters are often less expensive than gas heaters.
- You’ll also want to think about where you’re going.
If there is access to the water from the outside, a basic gas water heater will suffice. When installation, make sure to double-check your dimensions because mobile home door openings might be significantly smaller than those of a typical home.
Water Heater Tank Capacity
This is the most widely used type of water heater in the United States today. These devices have an insulated tank where water is heated and stored until it is required. Electrical, liquid propane, and natural gas-powered variants are also available. Water heaters powered by natural gas or propane often consume less energy and are less expensive to run than electric versions of the same capacity. Calculate the energy efficiency and annual running expenses of a water heater before purchasing one.
- There is no hot water stored in a tankless water heater.
- Because a tankless water heater simply warms water as it is consumed, it is often more energy efficient than a regular storage tank water heater because it is not required to keep unneeded water warm.
- A tankless water heater can only deliver a limited amount of hot water at a given time period.
- If you don’t need hot water from more than two sources at the same time, these units are an excellent alternative.
- Typically, the capacity of utility water heaters ranges from 2.5 to 19 gallons of storage capacity.
- Heaters for Mobile Homes – What You Need to Know Water heaters for mobile homes must be of a specified style.
- It is possible to have a gas or an electric water heater for a mobile home setup.
- In the event that you choose gas, make certain that you choose the suitable type for your installation (propane or natural gas).
- Purchasing a sealed combustion gas water heater is required if a gas heater will be encased with no access from the outside.
- Because mobile home door openings might be narrower than those of a typical home, it is important to double-check your dimensions before proceeding with the installation.
Minimum Gallon Capacity Recommendations
30 gallons for a family of 1 to 2 people 40 gallons for a family of 2 to 3 people 50 gallons for a family of 3 to 4 people 80 gallons for a family of 5 or more people
Gas Water Heater:
Thirty gallons per person or every family of one to two people 40-gallon household (for 2–3 people) Fifty gallons per family of three or four people. Eighty gallons for a family of five or more
Space for the Water Heater
If you don’t have enough room for a standard-sized water heater, there are other options. All of these solutions give the same degree of performance and may be used with either electric or gas systems (natural gas or propane).
Lowboys or Short Water Heaters
These water heaters are both shorter and broader than a standard water heater. They contain the same amount of water as their larger counterparts while yet being able to fit into tight spots such as crawlspaces and below cupboards. Lowboys are available in sizes ranging from 30 to 49 inches in height and can store up to 50 gallons of water.
Tall Water Heaters
High-capacity water heaters are available in sizes ranging from 50 to 76 inches in height and can accommodate up to 100 gallons of water. They’re perfect for basements or garages where there isn’t a concern about height. In addition, hybrid water heaters require additional room in order to perform correctly, so be sure to read the manufacturer’s instructions carefully before installing one of these units.
Advanced Technology
This feature is available for electric water heaters and prevents the higher element from burning out if the appliance detects that there is no water nearby.
ENERGY STAR ®and High-Efficiency Ratings
It is the most trusted and government-backed emblem of energy efficiency on the market today. This grade assists consumers in saving money while also conserving the environment via the use of energy-efficient items and procedures. Consider investing in a high-efficiency water heater to save money while also benefiting the environment. The energy factor (EF) rating of a water heater is used to determine its efficiency. The greater the efficiency factor (EF), the more efficient the model. However, while some of the most energy-efficient versions may be a little more expensive initially, they are meant to be more ecologically friendly and to save you money over time.
This information provides you with a sense of how the water heater model you’re considering is projected to perform, and it also includes an estimate of the model’s yearly operating cost, if applicable.
Intuitive Technology
A new generation of water heaters adapts the temperature and other operational aspects to your personal demands and usage patterns in a simple and easy manner. Improved energy economy, enhanced durability, and smarter performance are just a few of the advantages of choosing a heater that is integrated with artificial intelligence of this type.
A Premium Electronic Gas Valve
Certain gas water heaters now include an electronic gas valve, which is more efficient. This results in more consistent and precise performance for better temperature control and faster hot water recovery than a standard mechanical gas valve since it has fewer moving parts than a mechanical gas valve. Using a light-emitting diode (LED) indicator, you can validate that the pilot is lighted and get diagnostic input on how well the system is performing.
With a thermopile, this novel valve can operate entirely on its own power. A thermopile is a device that transforms heat energy into electrical energy. Because there is no requirement for an external power supply, installation is straightforward.
Wi-Fi Water Heater Capabilities
Electric water heaters that have a Wi-Fi module are currently available on the market. It allows you to regulate the temperature of your water from a distance. Set up a customized schedule so that hot water is only accessible in your water heater tank when it is needed, resulting in significant savings on your energy expenditure. It will also give you an alarm if your hot water supply is running low.
Accessories
Some electric water heaters are now equipped with a Wi-Fi module. Water temperature is controlled from a distance. Set up a customized schedule so that hot water is only accessible in your water heater tank when it is needed, resulting in a significant reduction in your energy expenditure. It will also notify you if your hot water supply is running low.
Expansion Tanks
The water heater’s expansion tanks are connected to the water heater by a plumbing system. It is the purpose of these water heater tanks to store the additional volume of water that can be created when cold water is heated in the tank.
Water Heater Timers
Plumbing connects the water heater expansion tanks to the water heater. It is the purpose of these water heater tanks to contain the additional volume of water that can be created when cold water is heated in the tank.
Water Leak Detectors and Alarms
Water leak detectors can be found on the floor or in a pan beside the water heater, depending on the model. A liquid leak or overflow will cause the alarm to detect the liquid and sound an audio alarm, alerting the homeowner that there is a problem. Some of these alarms are also integrated with Wi-Fi, allowing you to get notifications on your smartphone.
Water Heater Insulation Blankets
They are designed to be installed above the unit and to improve the insulating properties of the water heater. Heating systems installed in garages or other unheated areas benefit from the use of insulating blankets.
Water Heater Pans
There are many pans that sit beneath the heater and catch water from leaks or overflows produced by excessive pressure in the tank. The side of the pan features a hole for a drain hose, which may be used to remove any excess water.
Water Heater Stands
Water heater stands elevate gas-powered units off the ground, reducing the risk of a fire in the case of a flammable liquid spill in the immediate vicinity of the unit. If you’re replacing an old water heater and installing a stand along with your new one, your measurements, piping, and venting will be affected as a result. It will be necessary to hire a professional to install it if you do not have extensive plumbing expertise.
What Size Water Heater Do I Need?
Water heater stands elevate gas-powered units off the ground, reducing the risk of a fire in the case of a flammable liquid spill in the immediate vicinity of the heater. Replace an old water heater and include a stand with your new water heater. This will have an impact on your measurements as well as your plumbing and ventilation systems. It will be necessary to hire a professional to install it if you do not have significant plumbing knowledge.
Storage Tank or Tankless?
Storage tank water heaters and tankless water heaters are the two most common types of water heaters.
You must first select whatever sort of water heater you intend to purchase before determining the appropriate size.
Tankless
Tank-style water heaters and tankless water heaters are the two most common types of water heaters. Determine whatever sort of water heater you intend to purchase before determining the appropriate size for it.
- Per minute, only a limited amount of hot water is available
- Not suitable for all people
- High initial outlay of funds
Storage tank
Tank-style water heaters are significantly more widespread than tankless water heaters. This type of water heater is distinguished by the presence of an insulated tank that reserves hot water until it is required. We’ve all had the unpleasant experience of running out of hot water or having to wait for the water to heat up before getting into the shower. These sorts of events occur because storage tank units have a recovery increase, which refers to the quantity of water they can heat in an hour, which causes them to overheat.
Pros:
- Hot water that is available for a limited length of time
- Not as energy-efficient as before
Water Heater Sizes
There are many different sizes of hot water heaters available, and you must first assess your usual water use in order to make an informed decision on which size to purchase. Several important considerations should be kept in mind in order to further limit down your search:
- Natural gas, liquid propane, or electricity as a fuel source: Which will you choose? Is it possible that your water heater will connect to your boiler? Making this determination initially will assist you in narrowing down your selections and making the purchasing experience much simpler
- Physical dimensions- Make certain that the water heater you choose will fit into the area you have allotted in your home. Residence Size- Do you live in a little condo or in an enormous house? Is it simply you and your spouse, or do you have a large number of relatives and friends? When buying for a water heater, the size and occupancy of your family are two of the most critical considerations to make since you don’t want the person who showers last to be stranded with cold water.
Natural gas, liquid propane, or electricity will you be using as a fuel source? Or, will your water heater be able to connect to your central heating? This will assist you in narrowing down your alternatives and making the purchasing experience much more straightforward. Consider the physical dimensions of the water heater you choose to ensure that it will fit into the available space in your home. Residence type- Do you live in a little condo or in an enormous house?— Or do you have a large family that includes more than just you and your spouse?
What Size Water Heater Do I Need?
For those of you who are considering a storage tank water heater, the following is a general reference to the storage tank capacity:
- In order to accommodate 1 – 2 people, you’ll need a water tank with a minimum capacity of 30 gallons. A tank with a capacity of at least 40 gallons is required for 2 – 3 persons. You’ll need at least a 50-gallon capacity tank (electric) or a 40-gallon capacity tank (natural gas or liquid propane) if you’re cooking for 3 – 4 people. If your household has five or more members, you’ll need an 80-gallon electric tank or a 50-gallon natural gas or liquid propane tank.
Tank for storing items Hot water heaters are scaled based on the amount of BTUs they use and the amount of water they hold in gallons. Again, the more the amount of time you rely on hot water on a daily basis, the greater the amount of BTUs and capacity you will require. Consider, for example, how many showers individuals in your home take as a result of the consequences of their actions. If you have four individuals each take a ten-minute shower over the course of an hour, you will consume around 40 gallons of hot water in total.
- It only takes one person to take a longer shower for the tank to be completely empty.
- If you’re thinking about taking the tankless way, your purchasing experience will be a little different.
- You must, however, keep the following two considerations in mind: The pace of flow and the temperature rise.
- In order to calculate the required temperature rise, subtract the entering water temperature from the desired exiting water temperature and multiply the result by 100.
- Before making a purchase choice, conduct some investigation and testing to determine the temperature of your ground water.
In this scenario, a tankless water heater with a temperature increase of 50 degrees Fahrenheit would be appropriate. Based on an average ground water temperature of 50 degrees, the following are the sizes of tankless units you would require based on your usage:
- You’ll need at least 3.5 GPM if you’re running 1 or 2 fixtures at the same time. If you want to run two or three fixtures at the same time, you’ll need at least 5 GPM. If you want to run three or four fixtures at the same time, you’ll need at least seven GPM. If you want to utilize five or more fixtures at the same time, you may require additional tankless units to be installed in succession.
Making a Decision
We hope that this information has assisted you in better understanding the many elements and sizes to consider when selecting a new water heater. Total Home Supply has a wide variety of water heaters, including both storage tank and tankless models, all of which are eligible for free shipment to anywhere in the contiguous United States. If you require any extra assistance before to making your purchase, please do not hesitate to contact us. Our in-house specialists would be pleased to assist you in selecting the most appropriate unit for your water heating requirements.
Sizing a New Water Heater
A correctly sized water heater will satisfy the hot water requirements of your family while also functioning more effectively. As a result, when choosing a water heater, be certain that it is the appropriate size. These are the guidelines for sizing these systems, which you can find here:
- Water heaters that are tankless or demand-type
- Solar water heating systems
- Storage and heat pump (with tank) water heaters
- And other options.
Consult a trained contractor for assistance in sizing combined water and space heating systems, which may include certain heat pump systems, as well as tankless coil and indirect water heaters. If you haven’t already decided on the sort of water heater that would be most appropriate for your house, read on to learn more about choosing a new water heater.
Sizing Tankless or Demand-Type Water Heaters
When rating tankless or demand-type water heaters, the greatest temperature rise that may be achieved at a given flow rate is taken into consideration. For this reason, in order to calculate the appropriate size of a demand water heater for your home, you must first estimate the flow rate and temperature increase that will be required for its application (either the entire house or a distant use, such as a bathroom). To begin, make a note of the number of hot water gadgets you anticipate using at any given moment.
- This is the intended flow rate that you’ll need for the demand water heater that you’ve purchased.
- You may estimate the flow rate by holding a pan or bucket under the faucet or shower head for a minute and measuring the flow rate that way.
- (or liters per minute).
- Installing low-flow water fixtures can help to lower flow rates.
- Assume that the entering water temperature is 50 degrees Fahrenheit (10 degrees Celsius) unless you know differently.
- Water should be heated to 120 degrees Fahrenheit (49 degrees Celsius) for the majority of applications.
- For dishwashers without internal heaters and other similar uses, you may wish to heat your water to 140 degrees Fahrenheit (60 degrees Celsius).
- When the water temperature reaches 140 degrees Fahrenheit, use caution since it raises the risk of scorching.
- At a flow rate of 5 gallons per minute through gas-fired demand water heaters and 2 gallons per minute through electric demand water heaters, a temperature rise of 70 degrees Fahrenheit (39 degrees Celsius) is often achieved.
Some tankless water heaters are thermostatically regulated, which means that they may adjust their output temperature based on the amount of water flowing through them and the temperature of the water entering them.
Sizing a Solar Water Heating System
Basic system sizing entails calculating the total collector area and storage capacity required to satisfy 90 percent to 100 percent of your household’s hot water demands throughout the summer. Solar system contractors utilize spreadsheets and computer programs to assist them assess the size of their systems and the number of collectors they need.
Collector Area
Sizing your solar water heating system essentially entails establishing the total collector area and storage volume you’ll require to supply 90 percent to 100 percent of your household’s hot water demands throughout the summer. Solar system contractors utilize spreadsheets and computer programs to assist them in determining the size of their systems and the number of collectors they need to install them.
Storage Volume
A modest storage tank (50- to 60-gallon capacity) is normally suitable for one to two individuals, although a larger tank may be required. It is sufficient for three to four persons to use an 80-gallon storage tank of medium size. A big tank can accommodate four to six people comfortably. Active systems have a solar storage tank that grows in size in proportion to the size of the collector – generally 1.5 gallons per square foot of collector for active systems. When the demand for hot water is minimal, this helps to keep the system from overheating and breaking down.
Other Calculations
Another set of calculations required in estimating your solar water heating system is analyzing the solar resource available on your construction site, as well as establishing the optimal orientation and tilt of the solar collector. For further information on these calculations, please see thesolar water heaterspage.
Sizing Storage and Heat Pump (with Tank) Water Heaters
You should use the water heater’s first hour rating to determine the correct size for your home – this includes heat pump water heaters with tanks. The first hour rating indicates the amount of gallons of hot water that the heater can provide per hour of operation (starting with a tank full of hot water). The tank capacity, heat source (burner or element), and size of the burner or element are all factors to consider. The first hour rating is labeled as “Capacity (first hour rating)” in the upper left corner of the EnergyGuide label, which is displayed on the screen.
The first hour rating may also be found in product literature provided by the manufacturer.
To estimate your peak hour demand, do the following:
- Determine what time of day (morning, noon, or evening) you use the most hot water in your house and record that information. It’s important to consider the amount of people that will be living in your house. Making an estimate of your maximum hot water use during this one-hour time of the day—also known as your peak hour demand—can be done using the worksheet below. Please keep in mind that the spreadsheet does not estimate total daily hot water use.
Decide what time of day (morning, lunch, or evening) your household consumes the most quantity of hot water. It’s important to consider the quantity of people that will be living in your house. Making an estimate of your maximum hot water use during this one-hour time of the day—also known as your peak hour demand—can be done by using the worksheet below.
Please keep in mind that the worksheet does not provide an estimate of total daily hot water use.
| Use | Average gallons of hot water per usage | Times used during 1 hour | Gallons used in 1 hour | ||
|---|---|---|---|---|---|
| Shower | 20 | × | = | ||
| Shaving (.05 gallon per minute) | 2 | × | = | ||
| Hand dishwashing or food prep (2 gallons per minute) | 3 | × | = | ||
| Automatic dishwasher | 7 | × | = | ||
| Clothes washer | × | = | |||
| – Top-loader | 25 | ||||
| – H-Axis | 15 | ||||
| Total Peak Hour Demand | = |
| 3 showers | 20 | × | 3 | = | 60 |
| 1 shave | 2 | × | 1 | = | 2 |
| 1 hand dishwashing | 3 | × | 1 | = | 3 |
| Peak Hour Demand | = | 66 |
*Estimates are based on averages derived from a variety of information published on the internet, including government sources. Various calculators are available on some water heater manufacturer websites, which are depending on the duration of the use case and other criteria.
Water Heaters for Big Families
If you have a large family, you are probably well aware of the daily battle for the restroom that takes place. It can be difficult enough to get 5 minutes to yourself in the bathroom, let alone 5 minutes with enough hot water remaining to shower in, let alone both! It’s simple for a family to consume enormous amounts of hot water without even realizing it, thanks to the number of showers required, the number of loads of laundry needed to be cleaned, and the number of filthy dishes that need to be washed.
Some possible options include upgrading to a larger water tank and a more efficient water heater.
The Importance Of Tank Size
You might choose to purchase a larger tank in order to accommodate more water. With a larger tank, you will be able to store more hot water at a time, which will be beneficial in some situations. To heat the water, you may use either natural gas or electricity. Tank water heaters are simple to install and are extremely cost-effective, both in terms of the initial purchase price of the unit and in terms of the cost of repair. In exchange, it will take up more space and will take longer to heat up the water inside it; once that water is gone, you’ll have to wait approximately 30–40 minutes for the average gas water heater to reheat, and approximately twice that amount of time for the average electric water heater to re-heat.
If this is the case, one element to consider is the size of the tank.
As a result, a 50-gallon tank would be sufficient for the average family of two to three children.
However, the reality is that these estimations may be much different from what your family’s actual water use is since they do not take into consideration how frequently members of your family shower, do laundry, and use water in other activities.
Going Tankless
Purchase a larger tank so that it can contain more water if space is available. When you get a larger tank, you will be able to hold more hot water at a time, which is a benefit. When it comes to heating the water, you may choose between gas or electricity. Tank water heaters are simple to install and are extremely cost-effective, both in terms of the purchase price of the unit and in terms of the cost of repairing or replacing the unit. In exchange, it will take up more space and will take longer to heat up the water inside it; once that water has been used up, you will have to wait approximately 30–40 minutes for the average gas water heater to reheat, and twice that amount of time for the average electric water heater to heat up again.
Adding 12 gallons for each additional family member is a good approach to estimate the size of the tank you’ll need.
Other estimates state that you’ll need a 30–40-gallon tank for 1–2 people, a 40–50-gallon tank for 3–4 people, and a 60–80-gallon tank for 5 or more people, depending on how many individuals are in your group of 1–2.
Water heater repair technicians with extensive knowledge can assist you in determining the optimal size for your family’s needs and making the necessary selection.
It’s Personal
You might also choose to get a larger tank in order to accommodate more water. With a larger tank, you will be able to hold more hot water at one time, which is a benefit. To heat the water, you may use either gas or electricity. Tank water heaters are simple to install and are extremely cost-effective, both in terms of the purchase price of the unit and in terms of the cost of repair. The disadvantages are that it will take up more room and that it will take longer to heat up the water within it; after that water is gone, you’ll have to wait around 30–40 minutes for the usual gas water heater to reheat, and double that amount of time for the average electric water heater.
If this is the case, one element to consider is the size of the tank.
As a result, a 50-gallon tank would be sufficient for a typical family of 2–3 children.
However, the reality is that these estimates may differ from what your family’s actual water use is since they do not take into consideration how frequently members of your family shower, wash laundry, and use water in other ways.
What Size Hot Water Tank Do I Need?
As reported by the United States Department of Energy, water heaters account for 14 percent to 25 percent of a household’s yearly energy use. When it comes time to install a new hot water heater, it’s critical to select one that is the proper size for your house and family’s requirements. In the event that you purchase a unit that is too large, you may incur greater water and energy costs as a result of the additional stand-by time required to keep the hot water. A smaller water heater on the other hand increases the likelihood of running out of hot water and forcing your unit to run continuously in order to keep up with your home’s water demand; in addition, there will be a lot more wear and tear on your water heater, which could result in a shorter unit’s life expectancy.
Estimating Peak Demand – First Hour Rating (FHR)
Traditional storage tank water heaters must be able to keep enough water in the tank to fulfill the peak demand of your household. There is a First Hour Rating (FHR) on every water heater, which you will use to establish whether or not a certain storage tank is the proper size for your needs or not. In gallons per hour, this refers to the amount of hot water that the heater can produce (starting with a full tank of hot water).
According to standard practice, the total number of people in your house is multiplied by 12, which is the average amount of hot water consumed by one person during their peak consumption period (typically 12 gallons).
How to Calculate Family’s Desired FHR
When selecting a water heater, be sure that the first hour rating is within a few gallons of the figure you calculated in step one. Choose from one of the calculations shown below to find the appropriate size of tank for your family’s requirements (you might need to adjust that figure a bit if you have a large bathtub, multi-head shower or other special considerations).
Typical Breakdown
- 30 gallon water heater for 1-2 people
- 2-3 people for 40 gallon water heater
- 3-4 people for 40-50 gallon water heater
- 5 or more people for 50-80 gallon water heater
Equation for Average Household:
- FHR is calculated by multiplying the total number of persons in your home by 12 gallons. For example, four persons multiplied by twelve equals a 48-gallon water heater.
More Precise Measurement:
- Calculate the most water-intensive times of the day for your household (morning, lunch, and evening). It’s important to keep in mind the number of people that live in your home
- Use the grid below to estimate your maximum hot water use during this one-hour period of the day. Using this method, your FHR will be calculated. (This does not represent an estimate of total daily consumption.)
** A water heater model with an FHR of 36-40 gallons would be required for this family. One of the most important considerations when deciding what size water heater to purchase is determining the appropriate size water heater for your family. You might be wondering if a tankless water heater is a good option for you – you can have all of your questions answered by downloading our tankless water heater guide. Wes Holloway is an American actor. Wes has been employed at TLC for 14 years now. He has a great deal of expertise in the home plumbing industry.
What size hot water heater do you need?
The size of your new hot water heater will depend on the number of people in your household when the time comes to replace the old one. If you get a tank that is overly large, you will increase the cost of your utilities while also wasting your money. Choose a tank that is too small, on the other hand, and you will run out of hot water at a moment when you most need it, such as when your in-laws are staying with you for the night. If you’re trying to decide which type of water heater to purchase, here are some things to keep in mind.
- You may use the first hour rating (FHR) of a water heater to assess if a storage tank is large enough to accommodate the workload you have.
- To begin, determine the number of individuals who live in your house.
- So, for a four-bedroom house, you’d compute the square footage based on the assumption that five people would be living there.
- If you had four individuals living in a three-bedroom house, the FHR would be 48 gallons (412 gallons per person per day).
- This should be plenty for your family’s need.
- When everything is said and done, the math tells us that the following should be effective for you:
- A 30-gallon water heater is sufficient for 1-2 persons
- 2-3 people require a 40-gallon water heater
- And 3-4 people require a 40-50 gallon water heater. A 50-80 gallon water heater is required for groups of five or more persons.
Now, before you make your final selection, there is one more thing to consider, and it is a very important one to take into account. When choosing a water heater, should you go with a typical storage hot water tank or opt for a tankless water heater? Tankless Water Heaters are a type of water heater that does not require a tank to be filled with water. The capacity of a tankless water heater is not measured in gallons of water stored, but in flow rates. The flow rate of a tankless water heater should be sufficient to meet the peak demand that your household is anticipated to make on the system.
Add the flow rates of each together.
Many versions have a maximum flow rate of 3.5 gallons per minute, which is sufficient for a sink faucet and a shower head combination.
It is worthwhile to examine which type of hot water heater is ideal for you as well as how much of a water heater you will require.
If you need assistance determining the size of water heater your family need, or if you want more information about the advantages and disadvantages of a tankless water heater, please call us at The Plumbing Source.
We’ll go through the numbers with you and make sure you have a hot water heater that’s the right size for your household.