Installation Instructions
INSTRUCTION SHEET
FOR OUTDOOR RETURN AIR FILTER BOX (FCOSFB)
The oponal return air lter box is designed to lter the air returning to your out-
side wood furnace from inside the house. The lter box comes with one (12”) start-
er collar and one pre-cut plate and screws to seal one of the (12”) round openings
to allow the air to be drawn in from the rear or top.
Instrucons for installaon:
This lter box is designed for interior use only. Do not install outside the home.
A return air duct is crucial to a balanced air ow for your furnace and must be installed or the furnace will not
perform.
Cauon: Never reduce the return air duct size less than 12” round or (113 sq. in.). Reducing the return air ow
will restrict the hot air ow and will cause excess strain on the blower motor.
The lter box can be placed in a basement or in the living area of the home.
If the living area is your choice, the lter box should be placed in the center of the home. This will allow air to
be pulled from the heat ducts in an even ow.
If the basement is your locaon choice, the lter box can be placed on the oor or aached to the oor joist.
Install a 12”round backdra damper to the return air lter box to keep air from reversing when the furnace
isn’t in use.
Always change lter every thirty days or sooner if needed. A dirty lter will restrict air ow and could overheat
your outdoor furnace or damage the blower motor. Filter size is 16” x 20” x 1”.
FCOSFBIS
HY-C Company LLC – 10950 Linpage Place, Saint Louis, Missouri 63132
For a look at HY-C’s complete catalog of chimney and replace accessories, visit us at www.hyccompany.com