Even though a tankless water heater does not have a storage tank, it can still be too small or too big for you, in terms of its ability to provide as much hot water as you need. A tankless water heater sizing calculator calculates the adequate size of tankless water heater that is enough for your needs.
This article will help you understand how to size your tankless water heater correctly. We will look at the basic calculations necessary, followed by explaining some of the other data that helps refine tankless water heater sizing. Once you know the foundational concepts that get factored into the calculation of a tankless water heater’s sizing, this article will look at Intellihot’s in-house tankless water heater sizing calculator. Backed by a sizing guarantee, we will look at what makes Intellihot’s sizing calculator an effective solution to all your tankless water heater sizing needs.
Even though a tankless water heater heats water on-demand, every tankless water heater can heat a different amount of water in a particular timeframe. Hence, you would need to calculate which tankless water heater would heat enough hot water to meet all your needs. For example, suppose the most amount of hot water you consume is 60 gallons between 9 am to 10 am every day. You would need a tankless water heater that can deliver 60 gallons of hot water per hour, or 1 gallon per minute to meet your peak demand.
When it comes to sizing a tankless water heater correctly, there are various facets to consider/know about:
One of the first factors to consider when sizing a tankless water heater correctly is the temperature rise. This is the difference in temperature between the water entering your water heater and the outlet water. Also known as ΔT, this attribute measures how much your tankless water heater needs to heat the water. Many places might have a higher incoming water temperature than others. The water heater would need to heat water lesser than in places that get incoming water at a higher incoming temperature.
The set temperature is usually a figure set by the property owner determining the ideal temperature that hot water leaving a water heater should be at. ΔT is simply the difference between this set temperature and the incoming water temperature of the place.
Flow Rate determines the amount of water flowing through a fixture in a particular time period. A flow rate of 5 gpm is equivalent to 5 gallons of water flowing through the fixture every minute. On the other hand, a flow rate of 10 gph is equivalent to 10 gallons of water flowing through the fixture every hour.
Flow rate is important during tankless water heater sizing as different applications consume hot water at different rates. For instance, a faucet would consume hot water much slower than a shower even when comparing a situation where equal amounts of water is passed through both.
Hence, you would need to determine the flow rate of each fixture in your property that consumes hot water. You would need these numbers to buy a tankless water heater that can adequately meet the flow rate demand of these fixtures.
For instance, a standard shower has a flow rate of 2 gallons per minute. Hence, your tankless water heater would need to be able to produce a minimum of 2 gallons of hot water every minute to be able to match the demands of your shower.
The process of selecting a tankless water heater is not as simple as choosing one that falls within your flow rate range. A tankless water heater’s hot water output cannot be simply calculated as the gallons of hot water it can output at any given time. This is because a tankless water heater would need different amounts of heat energy to produce the required gallons of hot water every minute/hour. For instance, if Place A receives incoming water at 70 degrees Fahrenheit while Place B receives incoming water at 80 degrees Fahrenheit, the same tankless water heater would need higher amounts of heat energy to heat the same amount of water in Place A.
Hence, tankless water heaters rely on a measure of heating output to convey their power. This heating output is measured by BTUs/hr. or British Thermal Units per hour. A 1000-BTUs/hr. water heater for example, can provide 1000 British thermal units of heat energy every hour. One British Thermal Unit is the amount of heat energy required to raise the temperature of 1 pound (0.12 gallons) of water by one degree Fahrenheit.
Knowing your hot water consumption patterns is crucial for sizing a tankless water heater. Suppose you figured out the flow rates of all the applications that produce hot water in your property. Knowing how much hot water your tankless water heater would need to produce is not simply about adding up these flow rates. In most scenarios, you would not have all your hot water fixtures running.
For example, let’s say you have four showers and 2 dishwashers. Suppose you consume the most amount of hot water in the morning between 9 am and 10 am. Suppose during this time, you have two showers and a dishwasher operating at the same time. A standard shower works at 2 gallons per minute while a standard dishwasher operates at 2.5 gallons per minute. In this scenario, you would need a tankless water heater that can provide hot water at 6.5 gallons per minute so that it can provide enough hot water to the two showers and the washing machine between 9 am and 10 am. A sum of 13 gallons per minute would be too high of an estimate for your hot water demands.
Hence, knowing your hot water consumption patterns is key to sizing your tankless water heater. These patterns allow you pick a tankless water heater that can meet the hot water demands of your busiest period. Consumption patterns allow you to avoid oversizing or under-sizing your tankless water heater.
Now that we know the factors to consider for sizing a tankless water heater, let us understand the scientific process or methodology of sizing a tankless water heater. Knowing how to size a tankless water heater covers most of the working of a tankless water heater sizing calculator.
Heat Output (BTUs/hr.) = Peak Flow Rate (gpm) * Temperature Rise (°F) * 500.4
The BTUs/hr result that you get is the minimum heating capacity that you should look for in a tankless water heater to meet your peak hot water demand. Hence, you should purchase a tankless water heater that provides a heating output that is slightly higher than this minimum heat output. However, the above is a simplified calculation.
In order to achieve a more reliable sizing result, more factors need to be taken into account. For instance, every tankless water heater model transfers heat to water differently. Hence, changes/additions might need to be made to the heat output formula. Moreover, your hot water usage patterns can only provide a rough estimate and potentially fail to account for some hot water requirements that you may not factor in. This is the reason water heater sizing calculators are necessary.
Now that we know how to size a tankless water heater correctly, let’s understand the working of a tankless water heater sizing calculator. This is what the process of most tankless water heater sizing calculators looks like:
A tankless water heater sizing calculator allows you to consider various tiny factors that can impact correct sizing. The formula and methodology mentioned in this article is a very bare-bones means to carry out water heater sizing and does not take into account many of the finer points involved. Moreover, if you plan to size a tankless water heater for a commercial property, tankless water heater sizing calculators become even more important as they can take into account the differences between each property type.
Intellihot has an in-house sizing calculator that guarantees accuracy. You can access it here. We are so confident of the sizing calculator that we guarantee the payment of additional equipment charges if our results do not meet your required demand. Various features allow our sizing calculator to be good enough to deserve a guarantee. Here are some of the features of our sizing tool that you should also look for in any tankless water heater sizing calculator:
A good tankless water heater sizing calculator should take into account real-world data to make accurate estimates. Using real world data proves to be more effective than just relying on theoretical concepts as it can account for finer details. Using real-world data can help consider any changes like a shift in groundwater temperature due to climate change. Figuring out hot water consumption patterns especially benefits from using real world data. This helps commercial properties even more. For example, real world data can be used to determine a typical peak hot water demand for a large hotel or a full-service restaurant.
Intellihot’s sizing calculators feed flow, temperature and climate/weather data to determine the appropriate size and number of tankless water heaters for any commercial property. This data helps the calculator avoid under-sizing or over-sizing a property by pointing out typical patterns of similar businesses.
An accurate tankless water heater sizing calculator should be acutely aware of the capacity of every tankless water heater in its roster beyond its specified metrics. A sizing calculator would typically help you size your property and also provide specific tankless water heaters that would be an appropriate fit. An accurate calculator should know every water heater that it can possibly recommend. Beyond the specified metrics, each tankless water heater is uniquely different with its own set of strengths and weaknesses. Factoring these characteristics is essential for an accurate sizing recommendation.
A good tankless water heater sizing calculator should be able to provide multiple options to a user. Multiple options allow users to choose a water heating system that suits them the best since there could be discrepancies with product availability and price sensitivity for each customer. Moreover, users might have additional considerations like floor space constraints that could vary.
Intellihot’s sizing calculator provides three different sets of tankless water heaters that a user can choose from. These sets account for varying concerns. One of the sets is the most cost-friendly one, while another provides additional redundancy and power to be on the safer side. There is also a third option that falls in-between and balances cost-friendliness with additional redundancy.
Setting up a water heater effectively takes more than accurate sizing. A good tankless water heater sizing calculator should provide some initial information regarding the installation and configuration requirements of the products that it suggests. Such information is necessary when assessing the ideal tankless water heater for any property.
Intellihot’s sizing calculator provides detailed configuration diagrams and specification requirements in its results. This information is incredibly helpful when deciding whether a tankless water heater might be a good fit for a commercial property.
A tankless water heater sizing calculator should be confident enough of its results to be able to provide a guarantee. Incorrect sizing can be costly. Oversizing would result in unnecessary costs while under-sizing would result in not having enough hot water.
Intellihot’s sizing calculators guarantee accurate results. If our sizing calculator does not meet the required demand, Intellihot will pay for any additional equipment charges.
Intellihot’s accurate tankless water heater sizing calculator is easy to use, free, and guarantees accurate results. You can access our tankless water heater sizing calculator by using the button below.
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