How Many Btu Tankless Water Heater?

36000 BTU vs. 40000 BTU Water Heater: What’s The Difference?

Water heaters are a modern convenience and necessity, but only when you have one with the right heating capabilities.Choosing between a 36,000 BTU water heater and a 40,000 BTU water heater comes down to capacity, and the latter can handle 50 gallons.Whether it be heating capability or water capacity, let’s explore the difference between a 36,000 BTU and a 40,000 BTU water heater.Choosing the right water heater for your home comes down to more than a few factors.

One of the most important factors, however, is how many BTUs it has.Short for British Thermal Unit, a BTU is a unit of energy.But is that level of energy the only difference between a 36,000 BTU water heater and a 40,000 BTU water heater?Aside from slightly better heating capability, a 40,000 BTU water heater also tends to have a slightly larger tank.The 36,000 BTU water heater is about 40 gallons while the 40,000 BTU water heater is around 50 gallons.Don’t want to do it yourself?

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What is a BTU?

The term ″BTU″ refers to the British Thermal Unit.This is a measurement of the amount of heat necessary to raise the temperature of a single pound of water by one degree Fahrenheit.The higher the quantity of BTUs, the greater the amount of heating power that the unit has.When referring to appliances, the BTU is typically used to quantify the unit’s heating and cooling capabilities.

BTU will be mentioned not just in relation to water heaters, but also in relation to air conditioners and any other sort of equivalent equipment that is used in the home.

Significance and Recovery Rate

The BTU output of a water heater is often used to rank water heaters in some way.This implies that they are rated according to the amount of BTUs they produce every hour.For example, if you have a 36,000 BTU water heater, it has the capacity to raise the temperature of up to 36,000 pounds of water by a single degree Fahrenheit per hour.That is equivalent to 360 pounds multiplied by 100 degrees.

The recovery rate, on the other hand, is the amount of time it takes for the water in the tank to heat back up.When you use a water heater, the hot water evaporates from the unit, allowing the unit to fill with cold water.The recovery rate refers to how long it takes to re-heat the water once it has been heated.Generally speaking, recovery rate is defined as the number of gallons of water that can be heated to 100 degrees Fahrenheit in one hour.It takes around 40 minutes to restore a conventional 40-gallon water heater tank from its initial state.

Size and Usage

The most popular method of determining the size of a water heater tank, on the other hand, is to simply measure the tank’s volume.Gallons are commonly used to describe this quantity in everyday speech.A 30- to 40-gallon tank is considered normal for a two-person household.For a group of five or more individuals, a container in the 50- to 80-gallon range would suffice.

Generally speaking, BTUs are more typically used in the ventilation, heating, and air conditioning industries to discuss the efficiency of the equipment in question.Water heaters are often compared based on their size or their recovery rate, which is most common among house owners.

The Main Differences Between 36000 BTU and 40000 BTU Water Heaters

If two water heaters have similar BTU ratings, they are likely to be almost identical in most other aspects.After all, BTU is a determinant that is pretty flat in its distribution.It has no influence in the characteristics of a certain water heater, thus such characteristics would not be relevant here.The heating capacity and tank size of a 36,000 BTU water heater and a 40,000 BTU water heater are the only two distinctions between the two models.

Let’s take a closer look at each of them individually.

Heating Capacity

The most noticeable difference between the two is the heating capacity of each.To put it another way, the 36,000 BTU water heater will never be able to heat as much water in an hour as the 40,000 BTU water heater.In practice, the difference is marginally more than insignificant, albeit it varies depending on the environment.A 36,000 BTU water heater will be sufficient for the average two-person household.

Although the 40,000 BTU water heater is more expensive, it may be more effective in providing hot water on a constant basis in houses where shower consumption is more frequent and intense.


The physical size of these two water heaters is the second most important element in choosing between them.Keep in mind that, for the most part, homeowners select the size of the unit that they require based on the capacity of the tank.No, they aren’t going to actually go on BTU.The capacity of a 36,000 BTU water tank is likely to be in the 30- to 40-gallon category.

This is the standard in the majority of modern residences.The water heater has a tank capacity of 50 gallons and has a BTU rating of 40,000.Despite the fact that larger tanks might be slightly more expensive to operate in the long run, they provide more constant and longer-lasting water heating.

A Higher BTU Rating is Better

Whatever way you look at it, the BTU rating is a measure of how quickly the unit recovers from its previous state.The faster the pace of recuperation, the sooner you will be able to utilize hot water once more.A greater BTU rating is strongly suggested for houses where appliances are continually in use.Electric water heaters (as opposed to tankless water heaters) may be a preferable choice for those who want a larger BTU.

Electric water heaters are often equipped with either a pair of 4,500-watt heating elements or a single 5,500-watt heating element, depending on the manufacturer.Having two elements, on the other hand, is preferable since they heat up significantly more quickly than a single higher-wattage heating element.

How to Calculate BTUs Needed

As a result of your investigation, you have determined that your water heater must be replaced. However, how can you know whether you are making the appropriate choice when it comes to a replacement? You conduct your study and come to the conclusion that BTU ratings are vital to your needs. What is the formula for calculating BTUs?

Step 1: Find the Capacity

Find out how much capacity your present water heater has by following these steps.Pay close attention to the sticker or tag that came with the water heater.The majority of the time, this is a label on the front of the water heater that contains information such as the capacity of the unit.Before making a decision on what to upgrade to, it’s important to understand what you’re dealing with.

Step 2: Creating an Equation

You may construct your equation based on the information included on the tag or label. In order to raise the temperature of a pound of water by one degree Fahrenheit, it needs a single BTU per pound of water. In the United States, a conventional water heater holds 40 gallons of water, with each gallon weighing 8.33 pounds.

Step 3: Calculate

It’s time to get down to business.You may calculate the amount of water needed by multiplying the size of your present water heater by its weight in gallons, which comes to 333.2 pounds of water.That means you’ll need at least 333.2 BTU to increase the temperature of the water by one degree Celsius.However, because most regions require more than one degree of heat, we want further information.

Step 4: The Final Calculation

It’s important to know what the average temperature of your water is; you can usually find this information from your local water provider.If your water is generally 50 degrees and you want it to be 140 degrees, you would subtract 50 from 140 to reach the desired temperature.It is then necessary to multiply the difference by the weight of the water, which is then multiplied by the total number of gallons.In this case, the answer comes out to 29,988 BTU, which suggests that your replacement unit would need to be at least 30,000 BTU in order to satisfy your requirements.

Video: How Much BTU Heat You Need

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What About Tankless Water Heaters?

If you want to save money on your water heater, you may consider upgrading to a tankless water heater.Tankless water heaters are significantly more energy efficient than their tank-based competitors.This is due to the fact that the tankless heater’s primary function is to heat water only when it is required.The term comes from the fact that there is no water tank to store it.

Tankless water heaters consume a significantly higher amount of BTUs than their tanked equivalents.Compared to the industry standard water heater tank, which consumes 36,000 BTU, the average tankless water heater consumes somewhere between 150,000 and 200,000 BTU on average.The reason for this is that tankless water heaters must heat the water to a temperature that is practically instantly reachable.It will take a significant amount of petrol to do this.In order to properly install a tankless water heater, you need first consult with a professional to establish whether your gas line has to be upgraded.

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Ryan Womeldorf is an American actor and director. Ryan Womeldorf has been writing professionally for more than a decade. He enjoys writing about building, plumbing, and other home-related issues on his blog. Ryan also enjoys hockey and has been a lifetime supporter of the Buffalo Sabres.

How many BTUs does a tankless water heater use?

Electric tankless heaters that use elements instead of a gas burner are also available, although they are not as effective at heating a complete house as gas tankless heaters.It takes a large amount of gas to heat the water to a proper temperature, often between 150,000 and 200,000 BTUs, which means that most homes will require an upgrade in the size of their gas line.As a general rule of thumb, for every GPM that is deducted from the total, a 10-degree rise in water temperature is permitted.Using this scenario, a 200,000 BTU water heater would be able to heat all of the running water in a house to 110 degrees Fahrenheit when the flow rate is 6.4 GPM, and it would be able to heat all of the flowing water to 120 degrees Fahrenheit when the flow rate is 5.4 GPM.

As a result, the question is whether it is possible to oversize a tankless water heater.It is recommended that you do not purchase an excessive or undersized tankless water heater, as this will result in unneeded difficulties such as an increase in the upfront price, increased running costs, and wasted water and energy – all of which will have an impact on your budget and time.What is the disadvantage of using a tankless water heater in this manner?Tankless water heaters provide an infinite supply of hot water while taking up less space, posing a reduced danger of leaking, being safer, and having an overall lifespan that is substantially longer than conventional water heaters.The most important drawback of tankless water heaters is that their upfront cost (both for the device and for installation) is substantially greater than that of tank-style water heaters (see chart below).Is it possible to fill a tub with water from a tankless water heater?

  • Filling a large tub with water from a tiny tankless water heater might take a long time.
  • Third, if a bigger water heater cannot be installed because of space constraints and a correctly sized tankless water heater is too expensive, you can install a second regular water heater next to your existing tank.
  • Two smaller water heaters can perform the same function as one larger water heater.

What does the BTU rating on a water heater mean?

Asked in the following category: General The most recent update was made on March 8, 2020.Definition.In thermodynamics, a BTU is the amount of heat required to elevate a pound of water by one degree Fahrenheit.More BTUs equate to more heating capacity.

The amount of water that may be poured into a 30-gallon tank ranges from 32,000 to 88,000 gallons.On a 40-gallon tank, a typical input is 34,000 BTUs, and on a 50-gallon tank, a typical input is 36,000 BTUs.The higher the BTU intake and efficiency, the more quickly the recovery may be achieved.Electric water heaters are commonly equipped with one 5,500-watt or two 4,500-watt elements, depending on the model.Besides that, what is an appropriate first-hour rating for a water heater?Example: The water heater holds 40 gallons of water and has components that are 5500 watts (electric water heater) 40 gallons multiplied by 7 (70 percent of the tank capacity) plus 22.5 (gallons per hour with an increase in temperature of 80 degrees) equals 50.5 gallons first hour rating.

  • Answer.
If your tank capacity is: 70% of your tank capacity is:
120 gallons 84 gallons

Similarly, many wonder what the BTU (British Thermal Unit) on a hot water heater means.The quantity of gas or energy consumed every hour to heat the water in the tank is referred to as the input.When the input is higher, the water heater can heat more water more quickly when it is needed.The amount of natural or propane gas used is measured in BTUs (British Thermal Units) per hour, and state gas inputs range from 30,000 to 75,100 BTUs per hour.

Is it preferable to have a short or a tall water heater?Short water heaters are available in lengths ranging from 30 to 49 inches and can store up to 50 gallons of water.The term ″short guy″ is used to refer to tall water heaters.Tall water heaters may contain up to 100 gallons of water and have a height ranging from 50 to 76 inches.They’re perfect for basements or garages where there isn’t a concern about height.

How Many Btu Does A Tankless Water Heater Use? [Comprehensive Answer]

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How much btu does a tankless water heater use is the question that you’re looking for.On this page, we have compiled the most accurate and thorough information available to provide you with a complete response to the question: What is the btu consumption of a tankless water heater?Do I Need a Tankless Water Heater of a Specific Size?The Dimensions of Your Residence.

Tankless water heaters are available in a variety of sizes.The rate at which water flows through your home.We’ve established that tankless water heaters are different from traditional tank heaters in that they steam the water as it flows into the tank.Temperature increase..The number of people in your household..While heating your water, a standard gas water heater may consume 30,000 to 50,000 BTUs of natural gas or propane, depending on the model.

  • If you use a tankless water heater, it can take anything from 150,000 to 200,000 BTU to do the same thing because it heats your water on demand.
  • One pound of water may be heated by one degree Fahrenheit in one hour, which is measured in BTUs (British Thermal Units), which are units of energy.
  • Water weighs 8.3 pounds per gallon of liquid.
  • You will require 8.3 x (212-70) = 1,178.6 BTUs to boil one gallon of water starting at 70°F in one hour at a constant rate.
See also:  How Big Is A Hot Water Heater?

Can a tankless water heater run out of hot water?

Because there is no source of hot water that may be drained, a tankless system is the most energy efficient option. As opposed to this, the water heater warms water only when it is required. As long as there is demand, it will continue to operate in this manner – which means you will never run out of hot water!

Does tankless water heater use more gas?

According to, ″demand (or tankless) water heaters can be 24 percent to 34 percent more energy efficient than conventional storage tank water heaters for homes that use 41 gallons or less of hot water daily.″ Demand (or tankless) water heaters can be 24 percent to 34 percent more energy efficient than conventional storage tank water heaters.Tankless water heaters (especially if they are gas-fueled) can save households more than $100 per year if they are kept in operation for a long time.

What is BTU in tankless water heater?

The British thermal unit, or BTU, is a unit of energy that is used to measure the heating and cooling capacity of many types of equipment, such as water heaters, air conditioners, and other similar items.

What temp should tankless water heater be set at?

The temperature of your water should be between 100 and 115 degrees Fahrenheit when it is being heated. If the temperature of your groundwater is 60 degrees and you want your shower to be 110 degrees, it will result in a 50-degree increase in temperature.

What is a good size tankless water heater?

Sizing Guide for a Residential Tankless Water HeaterHousehold Occupants are included in this guide. Usage It is necessary to have sufficient capacity (Measured in Gallon) 2-4 individuals are required. People in the 40-503-4 range Regular/Low40High50-75

Are higher BTUs better?

A heater with a greater BTU rating is more powerful — that is, it produces more heat — than a heater with a lower BTU rating, since it produces more heat. It can boost the temperature in your room by more than one degree Celsius every hour, allowing you to either heat a room more quickly or heat a greater space.

How much gas does a tankless hot water heater use?

How much propane does each of the different tankless propane water heaters consume in a year?(Table) Propane tankless unit capacity (measured in BTU): Propane use for 20 minutes each day on an annual basis: 65,000 British Thermal Units (6.5 GPM) 91.03 gallons per year (75,000 BTU) (7.5 GPM) Gallons per year: 105.03 Gallons94,000 BTU (9.8 GPM) 100,000 BTU 131.64 Gallons/Year 131.64 Gallons/Year (10.2 GPM) Each year, 140.04 gallons are produced.

Does BTU matter water heaters?

The recovery of gas-fired water heaters is a function of the BTU input and the overall efficiency of the system…. On a 40-gallon tank, a typical input is 34,000 BTUs, and on a 50-gallon tank, a typical input is 36,000 BTUs. The higher the BTU intake and efficiency, the more quickly the recovery may be achieved.

How often should you flush a tankless water heater?

For regular maintenance and cleaning of your tankless water heater, it is necessary to rinse those mineral deposits out at least once a year using a hose. Follow this straightforward procedure to guarantee that your tankless water heater performs and operates at peak efficiency.

How do I calculate BTU for water heater?

The Formula for Success Understanding how BTUs go through a system is mostly a mathematical exercise. When it comes to water, the calculation is as follows: System Delivered BTU = 500 times GPM times System Water Temperature Change.

How many gpm do I need for a family of 4?

A tankless water heater capable of producing 7 gallons of hot water per minute should be considered for a household of four. During peak hours, the average family consumes around 6.5 GPM. You’ll need to know how many appliances your family will be using at the same time in order to calculate the size of your tankless water heater.

How is BTU related to GPM in tankless water heater?

As a general rule of thumb, for every GPM that is deducted from the total, a 10-degree rise in water temperature is permitted.Using this scenario, a 200,000 BTU water heater would be able to heat all of the running water in a house to 110 degrees Fahrenheit when the flow rate is 6.4 GPM, and it would be able to heat all of the flowing water to 120 degrees Fahrenheit when the flow rate is 5.4 GPM.

How much propane does a 200000 BTU heater use?

A typical HVAC furnace consumes roughly 200,000 BTUs per hour, which is equivalent to approximately one gallon of propane. Tankless water heater — The water heater is often the second-highest energy-consumption equipment in the home, behind the refrigerator.

How many gallons per hour does a tankless water heater use?

Tankless water heater with a capacity of 40,000 BTU per hour or 1.5 gallons per day.

What size tankless water heater do I need for a family of 4?

Sizing Guide for a Residential Tankless Water HeaterHousehold Occupants are included in this guide. Usage It is necessary to have sufficient capacity (Measured in Gallon) 3-4 individuals are required. People who are regular/low40high50-755+ in their lives Regular/Low50

How many btu does a tankless water heater use? Video Answer

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How to choose a tankless water heater in 2022 – Complete Guide

The decision on which tankless water heater to purchase is one that will affect you for a long period of time. A tankless water heater that works well for others may not be the best choice for your needs. In order to assist you in making your selection, we have produced a checklist that might assist you in determining which tankless water system to purchase.

Let’s discuss some fectors for choosing a tankless water heater

1. Brand Selection

When settling on a tankless water heater, it is one of the most important elements to consider. It is not advisable to choose a tankless water heater brand only on word of mouth or hearsay. It is critical that you additionally check the following items:

  1. The length of the warranty
  2. whether or if they have a local service provider
  3. and, finally, how dependable are them?

Will they abandon you once they have sold you the apartment or will they not? When it comes time to choose a tankless water heater brand, it would be beneficial if you were clear on the following points.

2. Incoming Water Temperature

Another factor that might get in the way of you and your hot water is the temperature of the water in your location.For example, a tankless unit with a specified capacity that works well for someone who lives in a warmer climate may not be acceptable for you if you live in a cooler climate.This is due to the fact that the increase in temperature that the tankless water heater is required to bring about is distinct.A tankless device with a capacity of 3 gallons per minute may raise the temperature of water from 60° to 120° in less than one minute, resulting in a total capacity of 3 gallons per minute.

However, if the same tankless unit is required to raise the temperature of the water from 30° to 120°, the process will take significantly longer.The maximum capacity is 2.5 gallons per minute, which is a little amount of water.Therefore, if you live in a colder climate, you should consider purchasing a tankless unit with a slightly larger capacity than you require.

3.  Tankless Capacity

Each tankless water heater has a defined capacity for the amount of water it can heat at any given moment.As a result, you must determine how large of a tankless unit you will need to purchase in order to satisfy your requirements.But first and foremost, you must determine how much hot water you will use at any given time.There are two methods for estimating your hot water requirements; you may either use the following table to estimate your requirements or personally verify them using a bucket.

You may estimate the flow rate of fixtures by allowing them to run for a minute and then measuring the water flow rate to get an estimate of the fixture rate.Manual estimates are more accurate when it comes to estimating your wants and requirements.

4. Fuel type

  1. It is now necessary to choose a fuel for your tankless water heater once you have decided on the brand and capacity of your unit.
  2. In most cases, a gas-fueled tankless water heater is less expensive to operate than an electric tankless water heater since natural gas is often less expensive than electricity.
  3. However, this isn’t always the case.

So you must figure out which fuel is the most cost-effective power source, since this will have an impact on your savings.You must also evaluate the prices of these units as well as the prices of their fuel in order to determine which is most advantageous for you.Assume that there isn’t much of a difference between the pricing of gas and electricity.In such situation, a tankless unit that is powered by electricity is more advantageous for you.

  1. Because electric tankless units are less expensive per unit than gas-fueled tankless units, they are a good investment.

5. Energy Factor:

  1. Another important characteristic to look for in a tankless water heater is how efficient it is in conserving energy.
  2. The energy factor of a unit provides information about the unit’s energy efficiency.
  3. The energy factor of the majority of classic tank water heaters is between 0.5 and 0.6.

The implication of this is that, even though a tank unit consumes $1 of fuel, it only uses 50-60 cents of that fuel to heat the water, with the remainder being wasted.0.8 is the energy factor of the tankless water heater that is most commonly used with natural gas.At the same time, its condensing form has a 0.9 energy factor, which is rather impressive.In comparison, an electric tankless water heater has an energy factor of 0.98, which is considered to be favorable.

  1. While electric tankless systems offer higher energy and energy efficiency than gas tankless systems, they are more expensive to run due to the higher cost of electricity compared to gas.
  2. Important to remember about the energy component is that certain utility providers offer refunds on certain energy-efficient products.
  3. Assume that the purchased unit has a greater energy factor than the specified one.
  4. If this is the case, you may be entitled for rebates on your appliance.

6. Indoor or outdoor

  1. Tankless is available in both indoor and outdoor configurations.
  2. Both have their advantages and disadvantages.
  3. Consider the following scenario: you reside in an icy environment where there is a potential that the water within your tankless unit would freeze.

It is preferable to install an indoor unit in this situation.In hotter climates, outdoor units are a better alternative right now since they do not require additional ventilation to be installed.Because of the greater distance between the tankless unit and the fixture, an outdoor tankless unit may take longer to deliver water to the fixture.In the event that you are concerned about having a unit fueled by combustible gases inside your home, installing an outside unit will put you on the safe side of the equation.

  1. In addition, having an outside tankless unit is a convenience for those who do not want plumbers to be in their home all of the time.
  2. Therefore, the plumber will not be required to enter your home with the tankless water heater unit installed outside.
  3. In a similar vein, the filth or waste cleaned up by the plumber does not accumulate around your home, requiring you to clean it.

Frequently Asked Questions

  1. In order to use a tankless water heater, I need to know how much BTU it has.
  2. A tankless water heater has a minimum need of 190,000 BTU and a maximum requirement of 199,000 BTU.
  3. It is 4-5 times more than what is required by a typical tank water heater, which has a BTU rating of 40,000.

Is it possible for a tankless water heater to be too large?Tankless water heaters are available in a variety of sizes to accommodate the demands of various individuals.Understanding your requirements and purchasing a sufficient size to meet those requirements is a wise decision.Purchasing a larger size means you are paying for stuff that you will not use or utilize.

  1. Purchasing a lesser size, on the other hand, may leave you without what you need when you need it the most.
  2. For a family of seven people, what size tankless water heater do I need?
  3. To accommodate a family of seven, a gas tankless unit with a capacity of 11GPM is required, as is an electric tankless unit with a capacity of 34+ KW.
  4. However, such estimations are not precise due to the large number of variables that must be taken into account.
  5. The following are a few examples.

1.The average temperature of the water in your area.When water is freezing cold, a tankless water heater will take longer to heat than a conventional water heater.

In this situation, even if you have a larger unit, you will have a smaller capacity of hot water since tankless water heaters take longer to heat the water than conventional units.2.Your regular hot water requirements 3.Your hot water requirements during peak hours


The process of selecting a tankless water heater is very similar to the process of selecting the best option from a list of alternatives. By following the steps outlined above, you will be able to quickly identify a tankless water heater that meets your requirements and will serve as your partner for the rest of your life.

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How Much Propane Does A Tankless Water Heater Use? (+ Calculator)

  1. Propane tankless water heaters are the most energy-intensive appliances on the market (still about 41 percent more economic than conventional tank water heaters).
  2. There isn’t a propane-powered device on the market that consumes more propane than these on-demand heaters.
  3. What is the actual amount of propane that a tankless water heater consumes?

The amount of propane used (as well as the accompanying financial cost) is determined by three major factors.These are the ones:

  1. Size of a tankless propane tank in cubic feet. A propane tankless heater that produces 11 GPM and 199,000 BTUs will consume significantly more propane than a tankless heater that produces 7 GPM and 75,000 BTUs.
  2. The production of hot water. A propane tankless water heater that operates for one hour per day will consume more energy than a similar one that operates for twenty minutes per day.
  3. Efficiencies in energy use. On-demand hot water heaters powered by propane are often quite efficient. The efficiency of propane combustion (as measured by the EF factor) begins at 80 percent. The most energy-efficient propane tankless heaters have an energy efficiency of up to 99 percent (0.99 EF)
  4. these systems utilize the least amount of propane while producing the greatest amount of hot water.
  • We can determine how much propane is consumed by a tankless propane heater based on these three criteria. As an example of propane consumption, consider the following summary (we assume 100 percent output, 100 percent energy efficiency, and a $2.41 average national price per gallon of propane): a. The smallest 53,000 BTU unit (at the low end) consumes 0.58 gallons of propane every hour of operation. That equates to a $1.40/hour operating cost.
  • The largest 199,000 BTU unit (at the top of the line) consumes 2.18 gallons of propane per hour of operation. That equates to a $5.25/hour operating cost.
  • On Energy Star labeling, the standardized annual propane tankless heater use is specified at 200 gallons, which is consistent with industry standards. That works out to around $482 each year. When it comes to the real cost of operating a propane tankless water heater on an annual basis, the variety is enormous. According to our estimations, the following are the low-end and high-end expenses for a typical project: In the low-end scenario (53,000 BTU unit, 20 minutes/day, 0.99 EF), the water consumption is 71.22 gallons per year. The high-end model (199,000 BTU unit, 60 minutes per day, 0.80 EF) uses 992.80 gallons of water per year, which is approximately $171.64 per year. That works out to around $2,392.65 each year.
  1. Obviously, this doesn’t tell us a lot about how much propane is consumed by our personal propane tankless water heater, does it?
  2. Due to the fact that some families have tiny units, while others have larger units, and some households use these propane on-demand water heaters for one hour per day while others use them for just 20 minutes per day, the reasons for this are several.
  3. An online Tankless Propane Usage Calculator has been developed to assist everyone in accurately estimating the propane use of their particular unit.

You enter the size of your unit in BTUs, the energy efficiency of your unit, and an estimate of how many minutes a day your unit is operational.The calculator may be found lower down the page.The following is an example of a calculation for a 95,000 BTU (9.8 GPM), 0.95 EF propane tankless heater that is utilized 40 minutes per day: We’ve also computed how much propane different-sized propane tankless heaters consume per year based on how much time they’re used (20 minutes per day, 40 minutes per day, and 60 minutes per day, respectively) (results summarized in the table after the calculation).This will provide you with an approximate estimate of how many gallons of propane your tankless propane system consumes each year.

  1. Consider the following method for everyone to compute how much propane is consumed by the instantaneous water heater:

How To Calculate Propane Usage For Tankless Water Heater?

  1. Water is renowned for being difficult to heat.
  2. This is owing to the high specific heat (4.19 kJ/kg°C) of the material.
  3. Propane tankless heaters can heat more than 10 GPM of water in less than 15 seconds, making them ideal for commercial applications.

To do this, a tremendous quantity of energy is required, and all of that energy comes from the combustion of propane.We need to know the energy content of propane in order to compute how much propane is consumed by these on-demand heaters in order to heat up water on demand.The following energy content information is provided by the United States Energy Information Administration: 1 gallon of propane equals 91,452 British thermal units (BTU).To put it another way, burning a gallon of propane creates 91,452 BTUs (at 100 percent efficiency).

  1. Tankless propane water heaters are now available in a number of various sizes.
  2. If we look at Rinnai units (Rinnai manufactures the best propane tankless heaters; you can learn more about them here), we can see that they offer units ranging from 5.3 GPM (these units produce 53,000 BTU heating output at 100 percent capacity) to 11 GPM (these units produce 53,000 BTU heating output at 100 percent capacity) (these units produce 199,000 BTU heating output at 100 percent capacity).
  3. As an illustration, consider the largest household propane tankless heater available.
  4. If you look closely at the model number, you’ll see that it’s an 11 GPM Rinnai RU199iP, and the number 199 indicates that this propane tankless heater provides 199,000 BTU/hr of heating output when it’s functioning at full capacity.
  5. We already know that a propane-fueled unit of this size will generate 199,000 BTU of heating output.

We also know that 1 gallon of propane will provide 91,452 BTUs of heat when it is burned.With this information, we can determine how much propane is consumed per hour by a large tankless propane heater.Here’s how the math works out: Propane used in one hour equals 199,000 BTU (Heater Capacity) / 91,452 BTU per gallon equals 2.18 Gallons of Propane used in one hour According to this calculation, the largest propane tankless water heater will consume 2.18 gallons of propane per hour (at 100 percent output).

By calculating the propane consumption by the propane cost per gallon ($2.41 is the natural average), we can figure out how much it costs to run a gas heater for an hour on average.This is how we go about it: 2.18 gallon/hour (Propane use) x $2.41/gall (Propane cost) = $5.25/hour (Running Cost per Hour).You can very much use the same calculations for whatever tankless propane water heater you choose to use.To be sure, we must take into consideration the fact that propane does not burn at a 100 percent efficiency.When it comes to burning efficiency, the EF (Efficiency Factor) of the specific heater is important.All of this may appear to be a bit complicated at this point.

That’s why we made the process as simple as possible by including an easy-to-use propane use calculator as well as a summary table below the calculator.You can use it without restriction here:

Tankless Propane Water Heater Usage Calculator

  1. To figure out how much propane a tankless propane heater is expected to consume in a year, you just enter the unit’s size (in BTUs), its energy efficiency (which is typically around 95 percent), and the number of hours per day you expect to use the unit at full capacity.
  2. This last one — the number of jogging minutes per day – is the one with which the vast majority of homeowners struggle the most.
  3. The tankless propane heater (at full capacity) will be used for around 40 minutes per day in a typical household.

Here is a link to the calculator.In addition, you may mess about with the numbers a little bit: As you can see, the quantity of propane required by a tankless propane water heater is dependent on its size, efficiency, and how much water it is used each day on a daily average.This table contains some values derived for the most popular sizes of propane tankless heaters in order to make things even more straightforward:

How Much Propane Do Various Tankless Propane Water Heaters Use Per Year (Table)

For all computations in this section, we use an average 95 percent efficiency:

Propane Tankless Unit Size (in BTU): Yearly Propane Usage For 20 Min/Day: Yearly Propane Usage For 40 Min/Day: Yearly Propane Usage For 60 Min/Day:
53,000 BTU (5.3 GPM) 74.22 Gallons/Year 148.44 Gallons/Year 222.66 Gallons/Year
65,000 BTU (6.5 GPM) 91.03 Gallons/Year 182.05 Gallons/Year 273.08 Gallons/Year
75,000 BTU (7.5 GPM) 105.03 Gallons/Year 210.06 Gallons/Year 315.09 Gallons/Year
94,000 BTU (9.8 GPM) 131.64 Gallons/Year 263.28 Gallons/Year 394.92 Gallons/Year
100,000 BTU (10.2 GPM) 140.04 Gallons/Year 280.08 Gallons/Year 420.12 Gallons/Year
130,000 BTU (10.4 GPM) 182.05 Gallons/Year 364.11 Gallons/Year 546.16 Gallons/Year
160,000 BTU (10.7 GPM) 224.07 Gallons/Year 448.13 Gallons/Year 672.20 Gallons/Year
199,000 BTU (11 GPM) 278.68 Gallons/Year 557.36 Gallons/Year 836.04 Gallons/Year
  1. If you’ve read thus far, you should have a better knowledge of how much propane on-demand propane water heaters consume.
  2. An further excellent article addresses the question of what size on-demand heater you require; you can read it by clicking here.
  3. Any queries you have about your individual device can be asked in the comments section, and we will do our best to answer them as quickly as possible.

Tankless Water Heater Buyer’s Guide


  1. A tankless water heater, which may be installed on the wall of your garage, utility room, or even outside your home, can provide hot water for your whole home, from taps and showers to soaking tubs, dishwashers, laundry, and other appliances.
  2. Tankless water heaters provide hot water on demand, which means that assuming you install a properly sized unit, you will be able to have hot water whenever you need it, in as many locations as you need it, for as long as you need it.
  3. Tankless water heaters are ideal for small to medium-sized households.

In reality, these are two of the most significant advantages of tankless water heaters: they save space and money.There are two advantages to using solar hot water: 1) you don’t have to waste energy continuously keeping a large volume of water hot, and 2) you can generate an unlimited flow of hot water, so you don’t have to worry about running out of hot water during a long shower or filling a soaking tub completely.


  1. The three types of tankless units now available on the market are non-condensing, condensing, and hybrid condensing.
  2. Non-condensing tankless units are the most common.
  3. The essential principle for all three is the same even if they work in a somewhat different manner.

When you switch on the faucet, a gas burner ignites and a heat exchanger coil transfers heat to the incoming cold water flowing through the coil, resulting in hot water being delivered to your faucet through the faucet.Electric tankless heaters that use elements instead of a gas burner are also available, although they are not as effective at heating a complete house as gas tankless heaters.It takes a large amount of gas to heat the water to a proper temperature, often between 150,000 and 200,000 BTUs, which means that most homes will require an upgrade in the size of their gas line.With a condensing tankless water heater, you can take things one step further by incorporating a second heat exchanger to take use of extra exhaust heat, which allows you to heat your water even more efficiently while also lowering your running costs.

  1. A modest reservoir of 2 or more gallons is included in a hybrid tankless water heater to compensate for ″short draws,″ which are hot water requirements that do not require a large amount of hot water, such as hand washing.
  2. Maintaining a full supply of hot water in this little tank keeps the unit from having to fully fire up, increasing its overall efficiency.
  3. It is important to remember that tankless water heaters do not technically produce ″instant hot water,″ since hot water must still be allowed to flow from the unit to the faucet.


  1. For homeowners who presently have a traditional tank water heater and are wanting to replace it because their existing tank is outdated, inefficient, and/or leaking water, a tankless water heater is an excellent option.
  2. Other people move to tankless water heaters simply because they wish to minimize their annual water heating expenditures and/or have access to unlimited hot water.
  3. Despite the fact that tankless water heaters have been in use in Europe and Asia for more than two decades, they are only now beginning to achieve widespread acceptance and use in the United States of America.

Tankless water heaters are becoming increasingly popular for a variety of reasons, including the fact that they save valuable floor space in your garage or utility room, that they last 20-30 years because they are less susceptible to rust and leaks, that they can increase the resale value of your home, and that they are 40-50 percent more efficient than traditional tank water heaters.When compared to a typical gas tank water heater, which costs an average household around $250 per year to heat water, a tankless water heater may save an average household $75-$120 per year.Whether you’re worried about the environmental effect of your water heater or just want to reduce the expense of heating your water, a tankless water heater is a winner in both areas.Installation of a tankless water heater may potentially result in a refund from your utility company.

  1. product of superior quality and durability In addition, new federal laws governing water heaters, which are set to take effect in 2015, should be taken into consideration.
  2. If you have a gas water heater that holds more than 55 gallons, you will be forced to replace it with a water heater that has an efficiency rating of at least 82 percent starting in 2015.
  3. Tankless water heaters and condensing tank water heaters, both of which are more unusual and less well-tested, are the only products that receive this grade.
See also:  What Is The Benefit Of A Tankless Water Heater?


  • Hot water will never run out since a tankless unit heats on demand, thus there will be no shortage of hot water. Large families or residences with high hot water demands, such as those with a soaking tub or spa system, might benefit from a tankless water heater. A tankless water heater is a great option if you’re thinking about upgrading your tank from 40 or 50 gallon capacity to 66 or 80 gallon capacity or if you’re replacing an older, bigger tank.
  • It conserves space: The tankless unit has a significantly smaller footprint, which allows for more precious storage space in the home or garage.
  • Efficiencies in terms of energy: The most efficient standard gas tanks presently run at 62-67 percent efficiency, compared to 82-96 percent efficiency for today’s tankless water heaters, resulting in yearly savings of around $100 for the majority of households.
  • Tankless units have a longer lifespan and can survive up to twice as long as regular tanks, according to industry standards. You will have to replace your tankless unit half as often as you would your tank, which is a significant savings.
  • Increasing the selling value of your property: In certain situations, homeowners may be able to recoup the cost of a tankless water heater installation since a tankless water heater may enhance the sale value of your home.
  • A tankless unit conversion can be prohibitively expensive, with the entire cost of a job often ranging from $2,000 to $4,500 installed owing to the addition of gas lines and venting, as well as the installation of new water lines. Fortunately, because these retrofit expenditures will not be incurred during your future tankless installation, your next tankless installation will be substantially less expensive.
  • Waiting time at the faucet has increased: Installing a tankless water heater, in the opinion of many homeowners, will shorten the amount of time it takes for water to get hot at the tap. This is not true – in fact, in most circumstances, a tankless water heater will require around 15 seconds longer to provide hot water to the faucet.
  • It is not assured that lower operating expenses will be achieved: Some homes will consume significantly more hot water on a regular basis as a result of being able to get unlimited hot water on demand. This additional demand might cancel out the savings in power expenses that result from the installation of a more energy-efficient tankless water heater.
  • Electricity is required for tankless units: The fact that tankless water heaters rely on electricity means that they will not be able to supply hot water in the case of a power outage

Call (425) 636-7038 for fast service


  1. What is a flow rate, and what should I ask for when I want one?
  2. The gallon capacity, recovery rate, and first-hour rating of standard hot water tanks are all considered when comparing them, whereas the per-minute flow rate of tankless water heaters is considered when comparing them.
  3. In most cases, flow rates range between 4 and 12 gallons per minute for most main brands (GPM).

Consider the following typical hot water requirements, as well as the flow rate requirements for each:

Dishwasher 0.5 – 1.0 GPM
Bathroom sink 0.5 – 1.5 GPM
Kitchen sink 1.5 – 2.0 GPM
Utility sink 1.5 – 2.0 GPM
Washing Machine 2.0 – 2.5 GPM
Shower 1.5 – 2.5 GPM
Bath tub 2.5 –.0 GPM
Jacuzzi/Hot tub 4.0 – 5.0 GPM
  1. Consider how many of these requirements you could have at the same time in order to establish the maximum flow rate you’ll need.
  2. We recommend 6-7 GPM for a home with one bathroom; 8 – 9 GPM for a home with two bathrooms; and 9-11 GPM for a home with three or more bathrooms.
  3. Our experience has shown that units with a flow rate of 4-5 GPM are acceptable for studio flats, one-bedroom houses, and other application-specific requirements.

There are further solutions available for really big homes, including the installation of numerous tankless units in series.What is temperature increase, and how does it influence my decision on the maximum GPM?Depending on where you reside, the temperature of the water entering your home varies significantly.If you reside in the northern United States, your typical winter water temperature is 40-50 degrees Fahrenheit.

  1. If you reside in the southern United States, the typical winter water temperature is 50-65 degrees Fahrenheit.
  2. What location do I want my tankless water heater to be installed?
  3. When converting to a tankless water heater, many homeowners choose to move their existing water heater.
  4. Consider where you want to put your water heater, since there are both indoor and outdoor models available on the market these days.
  5. Installation of outdoor units is often less expensive than that of inside units.

The Efficiency Factor (EF) is a measure of how efficient a system is.The higher the efficiency factor (EF), the less it will cost to operate the tankless water heater.The efficiency of a heat transfer system measures the amount of heat transferred from an energy source to your hot water.

An EF of.92 –.96 indicates that the finest tankless water heaters are 92–96 percent efficient, which suggests that they are cost-effective.What brand should I go with, and why?When selecting a tankless water heater brand, it is important to evaluate the warranty, the availability of local service providers, and the dependability of the product.In the case that your water heater has to be maintained, check to see if there are any installers in your region that are qualified to operate on the particular device.


When selecting a tankless water heater, the two most significant factors to consider are the following:

Fuel type:

  1. If you presently have a gas tank water heater (natural gas or propane), you can install a gas tankless water heater.
  2. In order to service the high needs of tankless systems, which may reach up to 200,000 BTUs, you will almost certainly need to upgrade the gas line running from your meter to your heater.
  3. Existing electric water heaters will need to be replaced with gas or propane water heaters, or a gas connection will need to be added in order for the water heater to function properly.

It is possible to receive considerable rebates from some utility providers when converting from electric water heating to gas water heating.Switching to gas tankless water heating is an excellent decision and an excellent chance to take advantage of these rebates.As a result of the poor feedback, less-than-desirable temperature and flow characteristics of electric tankless water heaters, we do not recommend them for most whole-home water heating applications.


  1. It is critical to choose the most appropriate location for your tankless water heater in order to maximize space savings while also minimizing installation expenses.
  2. Consult with your installer to determine the most convenient location for a tankless water heater in your house.
  3. You should also consider the fact that the machine will require dedicated electricity.

Take note that in the event of a power failure, the device will not be able to supply hot water.Installers, on the other hand, can add a backup battery system if you so choose.The current plumbing rules and permit charges should be discussed with you by your installer before they begin work on your tankless water heater installation project in order to estimate the overall cost of the project.Make certain you understand the standards in order to ensure that your water heater is installed properly.

  1. Additionally, request that your installation assist you in understanding the periodic maintenance requirements of a tankless water heater.
  2. Although low maintenance expenses are associated with this product, some manufacturers prescribe a descaling procedure, the frequency of which will be determined by the quality of the water available in your area.
  3. This will assist you in extending the life of your tank.
  4. Additional advice and recommendations can be found in your owner’s handbook.


  1. Some utility providers provide incentives to customers who purchase and install a tankless water heater, therefore lowering the initial out-of-pocket costs.
  2. Call your utility provider to learn about incentives that are available in your region, or visit our rebates & incentives page for more information.
  3. Get in touch with Fast Water Heater Co.

RIGHT NOW if you want more information about tankless water heaters.

Call (425) 636-7038 for fast service

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How to Select the Right Size Tankless Water Heater

  1. Tankless water heaters are classified according to the highest temperature rise that may be achieved at a given flow rate.
  2. 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).
  3. It is vital to note that you should never attempt to save money by purchasing a tankless water heater that is undersized.

Step 1:

  1. Make a decision on the maximum number of devices that you wish to run and the overall flow rate of those devices.
  2. Then total their flow rates together (gallons per minute).
  3. This is the intended flow rate that you’ll need for the demand water heater that you’ve purchased.

Consider the following scenario: you anticipate to be able to operate a hot water faucet with a flow rate of 0.75 gallons per minute while also running a shower head with a flow rate of 2.6 gallons per minute concurrently.It would be necessary for the flow rate via the demand water heater to be at least 3.26 gallons per minute.Installing low-flow water fixtures can help to lower flow rates.

Step 2:

  1. Calculate the temperature rise that is necessary.
  2. To calculate the temperature rise, subtract the entering water temperature from the desired output temperature and multiply by 100.
  3. Assume that the incoming water temperature is 50 degrees Fahrenheit unless you know better.

You may rest assured that you will not undersize your tankless unit if you use the low temperature assumption).If you reside in a warm climate, the temperature of your water will most likely be significantly higher.For the majority of applications, water should be heated to around 105–115°.A demand water heater that delivers a temperature increase of 55° would be required in this scenario.

Step 3:

  1. Example of sizing: An typical shower will be between 104 and 106 degrees Fahrenheit and utilize 2.6 gallons of water.
  2. Assuming that the water temperature entering your home is 40° and that you wish to create enough hot water to run two showers at the same time, what temperature rise would you need to produce to achieve this goal?
  3. Answer: You’ll need to boost the temperature of the entering water from 40 degrees to 105 degrees.

The ability to heat a minimum of 5.2 gallon of water will be necessary.As a result, you’ll need a tankless water heater that can provide at least a 60-degree increase in temperature while also dispensing 5.2 gallons per minute of water.

Flow Rates

  1. Is there a limit to how much hot water you may use at once?
  2. You need to operate two showers at the same time, or a shower and a pair of sinks, or anything similar.
  3. The figure below illustrates the range of water consumption ranges as well as the typical water temperatures for a variety of fixtures.

In order to determine your total simultaneous water requirements, we recommend that you use the following reference points: 2.5 gpm for showers and 1.0 gpm for bathrooms.


Average Flow GPM

Average Temp.

Tub 4.0 GPM 102°F
Shower 2.5 – 3.0 GPM 104°F
Washing Machine 2.0 GPM 120°F
Dishwasher 1.5 GPM 110°F
Kitchen Sink 1.5 GPM 110°F
  1. Consider the following scenario: If you are taking two showers at the same time, you will require 5 gallons of hot water per minute from your tankless water heater.
  2. A shower and the washing machine would each use 4.5 gallons of water per minute from the water heater, thus you would need to turn on both at the same time.
  3. In any of these scenarios, you’ll want to make sure that the unit you choose is large enough to accommodate or surpass the amount of hot water you’ll require at the same time.

It is important to note that tankless water heaters are only designed to heat potable (drinking) water, and that the water entering a tankless device should not be pre-heated before use.

Other Sizing Notes

  1. Gas tankless water heaters have the ability to create a greater temperature rise per gallon of water than electric tankless water heaters.
  2. The majority of demand water heaters are rated for a wide range of water temperature inputs.
  3. An average flow rate of 5 gallons per minute via gas-fired demand water heaters and a flow rate of 2 gallons per minute through electric demand water heaters will result in a 70°F increase in water temperature in most cases.

Increased flow rates or decreased intake temperatures can occasionally result in a reduction in the temperature of the water at the furthest faucet.

Recommended Reading:

  • Learn how to use a washer dryer combo
  • learn about three common misconceptions about washer dryer combos
  • learn all you need to know about wall heaters in this comprehensive guide
  • and more.
  • Infrared Heaters 101: Your Complete Guide to Understanding Them

About Our Team

  1. Jeff Flowers is just a person who is plagued by a chronic case of curiosity and who frustrates everyone around him with his rambling nonsense.
  2. In his journey from beer to house living, Jeff is simply attempting to hack his way through life while also writing a few notes about his experiences along the way.
  3. Alternatively, you can listen to him rant about Austin traffic on Twitter at @Bukowsky, where you can follow his musings as well.

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