Empire Comfort Systems White Mountain Hearth DVCX36FP91N-1 Installation Instructions And Owner's Manual page 16

Vent Pipe Clearance
NOTE: Maintain two inches of clearance around vertical vent pipe
on first twelve inches. See Figure 16.
For horizontal vent, maintain a minimum one-inch clearance to
the bottom and sides of the vent, and three-inch clearance to
combustibles above the vent pipe. See Figure 17.
NOTE: A two-inch clearance around pipe for the first twelve inches
above the fireplace is required.
Figure 17 - Horizontal Vent Clearances
Page 16
INSTALLATION (continued)
Figure 16
Figure 18 - Flush Wall Installation
Figure 19 - Combustible Surround Installation
35362-5-0217