Minnesota Boiler License Practice Exam

Which of the following is NOT a way to determine boiler horsepower?

1. BTU (1bhp = 33,475BTU/hr)

2. Evaporation of water (1bhp = 34.5lbs/water/hr@212deg f)

3. Gas volume (1bhp = 10cf of gas)

4. Square feet of heating surface (1bhp = 10sq ft)

The correct answer is: Gas volume (1bhp = 10cf of gas)

The determination of boiler horsepower involves various established methods that quantify the capacity of a boiler in terms of thermal energy generation or heat transfer. BTUs and evaporation rates are standard measures because they relate closely to the heat energy required to produce steam or hot water and for system efficiency. One common method is using BTU ratings, where one boiler horsepower (bhp) is defined as equal to 33,475 BTU per hour. This method effectively links the thermal energy output of the boiler. Another method is the evaporation of water, where one bhp is defined as the ability to evaporate 34.5 pounds of water per hour at 212°F. This reflects the heat transfer capability of the boiler in terms of steam production. The measure of heating surface is also used, with one bhp typically requiring 10 square feet of heating surface. This measure relates to the actual surface area of the boiler available for heat transfer, influencing the boiler's efficiency and capacity. While gas volume might seem like a relevant measure for certain boiler types, it is not a standardized method for determining boiler horsepower. Instead, the first three measures directly relate to the thermal efficiency and output capability of the boiler. Therefore, using gas volume (10 cubic feet of gas) does