MHSC BUF400, Installation And Operating Instructions Manual, Page: 17 / 20

61D1013
17
FOR USE OF OPTIONAL AK-4 OUTSIDE AIR KIT
The use of outside air for combustion is optional unless required by building codes. It is only necessary to supply
outside combustion air to one side of the fireplace. Use the model AK4 combustion air kit.
MODEL AK-4 COMBUSTION AIR ASSEMBLY
1. Remove the cover plate from the 4" outlet opening location on the left
or right outside of the fireplace.
2. Place the insulation ring between the AK-4 starting collar and fire-
place wall.
3. Place the starting collar (4") into the hole on the side of fireplace. Fasten it in place with the four sheet metal
screws provided. See Figures 18 and 19.
Note: The air starting collar extends through the fireplace outer wrap. When the air starting collar is
securely attached, it will form a seal against the fireplace wall.
4. Attach outside duct to starting collar with duct clamp or screws. See Figure 19.
DO NOT remove the
cover if the outside air
will not be connected.
W
ARNING
Figure 18 - Attaching Outside Air Starting Collar
and Insulation Ring to Left Side of Fireplace
Figure 19 - Attaching Outside Duct
to Starting Collar
Insulation Ring
AK-4 Starting
Collar
Sheet
Meal
Screws
Left Side of
Fireplace
Shorter End
of Air Starting
Collar
Air Starting
Collar
Duct
Screws
Left Side of
Fireplace
5. Cut a 6-inch diameter opening for model AK-4 in the
outside wall covering where the outside vent is to be
located.
See Figure 20.
6. Select and cut a piece of duct long enough to attach
to the fireplace and stick out at least 3" beyond the
face of the wall to which the AK-4 inlet air vent will be
attached.
See Figure 19.
Figure 20 - Combustion Air Assembly for
Model No. AK-4
Nail
Holes
Use FP-4 U duct for maximum efficiency
and safety. Do not use a combustible
duct. Always use UL Listed Class 0 or
1 duct material.
W
ARNING
6" Diameter
Hole
Duct
Extending
3"min.
AK-4 Inlet
Air Vent
Screw
Screws
Continued