All piping must be carefully put up, and horizontal piping must have a pitch or slope of 1/4 to 1/2 in. in 10 ft., so that the water will flow out of the system as quickly as possible. A low place or sag in the pipes or heating coils may trap the water. The result will be that a noisy snapping or hammering will take place when steam is turned on.
The pipe coils are hung on rollers to allow for expansion. After the first heating season in a new building, and occasionally in all buildings, the piping system should be examined. The shrinkage and settling of floors may throw pipes and radiators out of place sufficiently to cause serious trouble in the action of the system.
The rule for finding the size of the main steam pipe is: Divide the amount of the direct heating surface in square feet by 100; divide the quotient by .7854; then take the square root of this last quotient. The result will be the diameter of the pipe in inches. (Pipe area = 1/100 of heating surface.)