What is the minimum size of feed water line on a boiler over 100 ft²?

What is the minimum size of feed water line on a boiler over 100 ft²?

• A. 1/2 inch
• B. 3/4 inch
• C. 1 inch
• D. 1 1/2 inch

Answer: (B)

Sizing the feedwater line is about meeting the water demand of the boiler as its capacity grows. As the boiler’s heating surface increases, it produces steam more quickly and needs more water to replace it. For boilers with more than 100 square feet of heating surface, the minimum feedwater line size is 3/4 inch. A line smaller than that, like 1/2 inch, would be too restrictive for larger boilers and could cause insufficient water flow, pressure drops, or water hammer during high demand. Larger sizes, such as 1 inch or 1 1/2 inch, are acceptable if the system requires higher flow, but they aren’t the minimum. Hence, the smallest acceptable size under these conditions is 3/4 inch.

Sizing the feedwater line is about meeting the water demand of the boiler as its capacity grows. As the boiler’s heating surface increases, it produces steam more quickly and needs more water to replace it. For boilers with more than 100 square feet of heating surface, the minimum feedwater line size is 3/4 inch. A line smaller than that, like 1/2 inch, would be too restrictive for larger boilers and could cause insufficient water flow, pressure drops, or water hammer during high demand. Larger sizes, such as 1 inch or 1 1/2 inch, are acceptable if the system requires higher flow, but they aren’t the minimum. Hence, the smallest acceptable size under these conditions is 3/4 inch.