Industrial Boiler Sizing Guide
When you start the process to replace your current boiler system, one of the first questions you’ll need to answer is “What size boiler do I need?” You shouldn’t just replace your current boiler system with the latest model. Instead, you need to do your homework first. After all, the goal of upgrading your boiler system is to improve the efficiency of your operation.
Using our industrial boiler sizing guide, you’ll be able to understand:
- Problems with undersized and oversized boilers
- The difference between sizing a hot water boiler and a steam boiler
- How to size an industrial boiler with our easy-to-use calculators
- The inputs that affect the size of your boiler
Problems with undersized and oversized boilers
Taking the time to properly size your boiler helps to make sure you have a reliable and efficient operation. More often than not, businesses operate with oversized boilers, which causes issues with boiler efficiency. While not as common, undersized boilers can also lead to production issues. Here’s what we mean:
Oversized boilers can result in constant cycling (turning on and off) which leads to
- Decreased overall boiler efficiency
- Unnecessary thermal fatiguing
Oversized boilers can result in constant cycling (turning on and off) which leads to
- Decreased overall boiler efficiency
- Unnecessary thermal fatiguing
Hot water versus steam boiler sizing requirements
Based on your production needs, you will select either hot water or steam boiler for your operation. A steam boiler is used to meet your high or low-pressure steam system requirements while a hot water boiler is typically used to provide hydronic heat. Since these types of boilers have different usages, there are certain inputs that matter more when estimating the size of your boiler.
Note: Some facilities require 100% redundancy while others operate on an N+1 scheme. This just means that the total load is split between N number of boilers and an additional boiler sits idle for availability if the main boiler was to go out of service (due to failure, safety device tripping, or maintenance).
Steam boiler sizing inputs
- Required operating pressure
- Load profile in pounds per hour of steam
- Maximum load
- Average load
- Minimum load
- Hours of operation
- Fuel input
- Redundancy required
Hot water boiler sizing inputs
- Circulation medium such as hydronic hot water, domestic hot water or glycol mixture
- Required operating pressure
- Load Profile in “btu/hr: or “MMbtu/hr”
- Max, Min, and Avg Flow (GPM)
- Max, Min, and Avg Supply Temp (°F)
- Max, Min, and Avg Return Temp (°F)
- Hours of operation
- Fuel Input
- Redundancy required
Boiler sizing definitions
Boiler Horsepower
- Boiler Horsepower is defined as the thermal energy rate required to turn 34.5 lbs of water at 212 °F to steam in one hour.
BTU/Hour
- A BTU, or a British Thermal Unit, is a unit of heat defined as the amount of heat required to raise the temperature of a single pound of water by 1 °F. BTU/hr is a measurement of heat energy transferred per unit time, in this case 1 hour.
Specific Heat
- Specific Heat is the intensive property of a material's heat capacity, or the amount of heat required to result in a unit change in it’s temperature. The specific is identified by dividing the heat capacity by the mass of sample material.
Specific Gravity
- Specific Gravity, also known as relative density, is the ratio of the density of a substance to the density of a reference. The specific gravity of liquids is typically measured in reference to water at 40 °F).
Density
- The density of a substance refers to its mass per unit volume. When comparing materials of the same size (volume) those with a higher density will have a larger mass (be heavier) than those with a lower density.
Delta T or ΔT
- Delta is a Greek letter that is used in Mathematics and Engineering to denote a change in a value. Delta T (ΔT) identifies the change in temperature between two points. Typically, in boilers, this is referring to the difference between the supply and return temperatures.
Gallons Per Minute
- GPM is a measurement of volumetric flow measuring the number of gallons to flow past a point of reference every minute.
How to size an industrial boiler with Atlas Copco?
We’ve given you the frameworks to help estimate the size of your boiler. If you’re looking for someone to double-check and triple-check the math, our team at Atlas Copco is happy to help.