WINCHESTER
BY
MORTEX
PRODUCTS
INC
FORT
WORTH,
TX
76106
Page
4
All local codes (State, City, and Township)
NOTE: All applicable codes take precedence over any
recommendation made in these instructions.
SECTION III: RETURN AIR AND
CLEARANCE REQUIREMENTS
Location
Access for servicing is an important factor in the location of
any furnace. Provide a minimum of 24 inches in front of the
furnace for access to the control box, heating elements, and
blower. This access may be provided by a closet door or by
locating the furnace so that a wall or partition is not less than
24 inches from the front access door.
Furnace Clearances
This furnace is approved for zero (0 inches) clearance to
combustible material on any part of the furnace exterior and
the inlet or outlet ducts. Refer to Table 4 for clearance to
combustibles information.
ALCOVE
(in)
CLOSET
(in)
ALL
6
0
0
18
6
0
CLEARANCES
MODEL
FRONT
OF
FURNACE
TOP
(in)
BACK
(in)
SIDES
(in)
DUCT
(in)
Table 4: Clearances to Combustibles
Figure 2: Closet Clearances
Return Air
In order for the furnace to work properly, a closet or alcove
must have a certain total free area opening for the return air.
FOR A/C and HP Furnaces (1/3 HP Blower)
Minimum 200 in² free area opening
Use Return Grille or Coil Cabinet
FOR A/C and HP Furnaces (1/2 HP Blower)
Minimum 250 in² free area opening
Use Return Grille, A/C Coil Cabinet, or any return grille
with a minimum 250 in² free area opening
FOR A/C and HP Furnaces (3/4 HP Blower)
Minimum 390 in² free area opening
Use Return Grille, or A/C Coil Cabinet, or any return
grille with a minimum 390 in² free area opening
Top Return Only – Recommended Grille Size
800 CFM – 20 X 20 Grille – 324 in²
1000 CFM – 20 X 25 Grille - 414 in²
1200 CFM – 25 X 25 Grille - 414 in²
1400 CFM – 25 X 30 Grille - 644 in²
1600 CFM – 25 X 30 Grille - 644 in²
1800 CFM – 30 X 30 Grille - 784 in²
Louvered Door and Top Return – Recommended Grille
Size
800 CFM – 10 X 20 Grille – 144 in²
1000 CFM – 12 X 20 Grille -180 in²
1200 CFM – 14 X 20 Grille - 216 in²
1400 CFM – 18 X 20 Grille - 288 in²
1600 CFM – 18 X 20 Grille - 288 in²
1800 CFM – 20 X 20 Grille - 324 in²
The return air opening can be located in a closet front door or
a side wall above the furnace casing, or in a louvered door on
the furnace. If opening for the return air is located in the floor,
side walls, or closet door anywhere below the furnace casing
height, a 6 inch minimum clearance must be provided on the
furnace side where the return is located to provide for proper
air flow. The 6 inch minimum clearance is not required if
there is a return grille installed above the furnace with the
sufficient return air opening.
Figure 3: Typical Closet Installations
Provisions shall be made to permit the air in the rooms and the
living spaces to return to the furnace. Failure to comply may
cause a reduction in the amount of return air available to the
blower, causing reduced air flow resulting in improper heating
of the living space. The reduced air flow may cause the
furnace to cycle on the limit causing premature heating
element failure.
