The Best Boiler Sizing Steps Used by the Pros

The Best Boiler Sizing Steps Used by the Pros


When it comes to the best boiler sizing practices, you shouldn't follow the mantra of "Go big or go home!" Grossly oversizing your boiler can lead to inefficiencies, waste, and other problems. On the other end of the spectrum, trying to generate savings by undersizing your boiler can cause decreased steam pressure, which can cause the system to collapse its steam space, causing low water alarms and burner lockout. 

In reality, it's best to right-size your boiler with the experts at Applied Technologies of New York. We use cutting-edge practices to ensure your boiler is properly matched to the steady state of demand for your facility as well as any short-term peak demands. In other words, we'll make sure your boiler is sized to meet the worst-case scenario of your facility. And once we've determined the best boiler sizing, we'll guide you to the most suitable equipment for your facility. 

Continue reading to learn more about boiler sizing tips and best practices used by the professionals. 

Understanding Boiler Sizing & System Selection

First things first, your engineer will work to determine the holistic heat energy or total heating load for your facility. An expert will consider the worst possible climate condition for your respective geographical area. In addition, they should make sure that there are no internal heat gains, which could be anything else in the facility that gives  off heat to lower the responsibility of the boiler. 

Understanding the Diversity Factor

A diversity factor may be applied whenever calculating the total heat load for a facility. The diversity factor means a portion of the total heating load can be removed from the equipment sizing considerations. In many instances, the engineer is fully aware the total calculated load will rarely be required because of how the building is used.  

Selecting the Best Boiler System 

After the total heating load for the building has been properly calculated, the best equipment can be selected. Let's say, for instance, the total heating load for your facility is 14,650 MBH. The majority of commercial heating boilers are engineered for round number capacities, like 6000 MBH, 4000 MBH, 3000 MBH, and down to 1500 MBH. 

In short, there's no combination of boiler capacities that will add up to the total load capacity of 14,650 MBH. As a result, you'll almost always have a combination of boilers with capacities greater than the calculated total load for your facility. In many instances, the additional capacity offers at least a single standby boiler for most of the year. 

In either case, oversizing your boiler isn't a bad thing; and in most instances, it's good. However, if you grossly oversize boilers it can cause a significant range of operational problems. And if you don't control it properly, it will lead to noticeable inefficiencies and waste.  

Sizing Boiler Plants for New Buildings 

Whenever a new building is constructed, there is nothing there but the ground. As a result, the architect must make plans that include the heating of the structure through different estimation methodologies used to determine the best size of boiler equipment. 

Similar to the method explained above, the design estimation must be made with the worst-case scenario in mind. After this specific situation is calculated, most engineers will include a safety factor as well as redundancy in the form of additional boilers or a single extra boiler. The redundancy factor is an extra measure in the event of a failure with one or more than one boilers. 

Boiler Sizing Process for Existing Buildings and Retrofits

When retrofitting a boiler for an existing building, engineers have a distinct advantage over the architect for new buildings. Instead of estimation, engineers can use the building's historical data. In general, there are two different types of retrofit boiler sizing methods:

  • Sales professionals will typically use a Business Estimation Mode that leans toward proving the business case for the retrofit.
  • Engineers will usually use the Public Estimation Model.

Public Estimation Model for Retrofit Boiler Sizing 

Because the chance for error always exists in building load calculations, some facilities choose to retrofit the boiler BTU for BTU. In other words, they rely heavily and only on the original calculations, which can present a range of problems. Why? Because the needs of your facility are destined to change or improve overtime. 

For instance, new building structural upgrades, such as new windows, can significantly improve the insulation of your facility and help reduce thermal losses. At the same time, electrical devices, personal computers, copy machines, etc can all add heat to your structure. With the Public Estimation Model, we may start out with the original design numbers, but we never rely solely or heavily on these calculations. 

Contact ATI of New York for Accurate Boiler Sizing and Equipment Selection

Accurately calculating the needs of your facility and choosing the best boiler system can be confusing and intimidating — whether you're looking to size a boiler for a new construction project or for a building retrofit. Because this process only happens once every 10 - 20 years, knowing where to start is often the biggest hurdle. However, the experts at ATI of New York offer decades of experience accurately sizing boilers and guiding our clients to the most effective boiler system. 

Contact ATI of New York today. 

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