=+12-37. Design the duct system shown in Fig. 12-38 for circular ducts. The fan produces a total pres-

sure of 0.70 in. wg at 1000 cfm. The lost pressure in the filter, furnace, and evaporator is 0.35 in. wg. The remaining total pressure should be divided between the supply and return with 65 percent used for the supply system. Diffuser and grille losses are shown on the diagram. Use equivalent lengths to account for fitting losses.

(a) Use the equal-friction method to size the ducts.

(b) Use the balanced-capacity method.

(c) Size the ducts with both methods using the program DUCT on the website.