12
GCUF/GRUF Vent-Free Fireboxes
Monessen • GCUF/GRUF Owner Manual • 71D0530 • Rev G • 01/20
COMBUSTION AIR
COMBUSTION AIR
1. Locate combustion air assembly at an exterior location
which is not likely to be accidentally blocked in any man-
ner. Locate assembly a min. of 12" above the snow line
to prevent blockage by snow accumulation.
2. Never mount the combustion air inlet assembly in a
garage or storage area where combustible fumes such
as gasoline might be drawn into the fireplace.
3. Combustion air can be drawn from the crawl space un-
der a house when an adequate supply of air is provided
by open ventilation.
4.
CAUTION: Do not take combustion air from attic
space or garage space.
5. Locate air supply inlet at least 3' away from any ap-
pliance vent terminal.
6. Avoid extremely long runs and numerous turns in the
duct leading from the fireplace to the combustion air
assembly. These conditions increase the resistance to
the free flow of air through the duct.
Refer to Figures
12 through 15
for methods of installing the outside air
for combustion assemblies.
FP2459
OA basement install
Above
Snow
Level
Ground
Level
FP2459
Figure 12 -
Basement Installation
15' Max.
FP2460
OA slab install
Inlet Grille
in Soffit
(Overhang)
FP2460
Figure 13 -
Concrete Slab Installation
(Optional Outside Air Runs)
FP2461
above basement
Duct
Extended
to Miss
Joist
FP2461
Figure 14 -
Installation Above Basement or
Crawl Space
To Outside Wall
FP2462
OA corner install
Outside
Wall
Inside Wall
FP2462
Figure 15 -
45° Corner Installation
on Slab Floor
NOTE: Fireplace model in illustrations may not be
representative of your appliance.
