Whirlpool WGFD293 Instruction Manual download pdf (Page 31)

Data in accordance with NFPA pamphlet Number 54.

CIRCULATING AIR AND FILTERS

Ductwork—Airflow

■ Duct systems and register sizes must be properly designed

for the CFM and external static pressure rating of the furnace.

Design the ductwork in accordance with the recommended

methods of “Air Conditioning Contractors of America”

Manual D.

■ Install the duct system in accordance with Standards of the

National Board of Fire Underwriters for the Installation of Air

Conditioning, Warm Air Heating and Ventilating Systems.

Pamphlets No. 90A and 90B.

■ A closed return duct system must be used, with the return

duct connected to the furnace.

NOTE: Ductwork must never be attached to the back of the

furnace.

■ For upflow installations requiring 1,800 CFM or more, use

either 2 side returns or bottom return or a combination of side

/bottom.

■ Flexible joints may be used for supply and return connections

to reduce noise transmission.

■ To prevent the blower from interfering with combustion air or

draft when a central return is used, a connecting duct must

be installed between the unit and the utility room wall.

■ Never use a room, closet or alcove as a return air chamber.

Bottom Return Air Opening—Upflow Models]

The bottom return air opening on upflow models utilizes a “lance

and cut” method to remove sheet metal from the duct opening in

the base pan.

1. To remove, simply press out the lanced sections by hand to

expose the metal strips retaining the sheet metal over the

duct opening.

2. Using tin snips, cut the metal strips and remove the sheet

metal covering the duct opening.

3. In the corners of the opening, cut the sheet metal along the

scribe lines to free the duct flanges.

4. Using the scribe line along the duct flange as a guide, unfold

the duct flanges around the perimeter of the opening using a

pair of seamer pliers or seamer tongs.

NOTE: Airflow area will be reduced by approximately 18% if

duct flanges are not unfolded. This could cause performance

issues and noise issues.

Duct Flange Cutouts

When the furnace is used in connection with a cooling unit, the

furnace should be installed in parallel with or on the upstream

side of the cooling unit to avoid condensation in the heating

element. With a parallel flow arrangement, the dampers or other

means used to control the flow of air must be adequate to

prevent chilled air from entering the furnace and, if manually

operated, must be equipped with means to prevent operation of

either unit unless the damper is in the full heat or cool position.

When the furnace is installed without a cooling coil, it is

recommended that a removable access panel be provided in the

outlet air duct. This opening shall be accessible when the furnace

is installed and shall be of such a size that the heat exchanger

can be viewed for visual light inspection or such that a sampling

probe can be inserted into the airstream. The access panel must

be made to prevent air leaks when the furnace is in operation.

When the furnace is heating, the temperature of the return air

entering the furnace must be between 55°F and 100°F (13ºC and

38ºC).

150 (45.7) 9 21 43 72 109 63 132 252 511 787

200 (61) 8 19 39 66 100 54 112 209 439 665

250 (76.2) 8 17 36 60 93 48 100 185 390 590

Propane Gas Piping Chart II

Tubing Size, O.D. Type L Nominal Pipe Size Schedule 40

Pipe or Tubing Length—ft (m) ³⁄₈" ¹⁄₂" ⁵⁄₈" ³⁄₄" ⁷⁄₈" ¹⁄₂" ³⁄₄"1" 1¹⁄₄"1¹⁄₂"

Never allow the products of combustion, including carbon

monoxide, to enter the return ductwork or circulation air

supply.

WARNING

A. Cut using tin snips.

B. Press out by hand.

C. Scribe lines outlining duct flanges.

D. Cut 4 corners after removing sheet metal.

Edges of sheet metal holes may be sharp. Use gloves as

a precaution when removing hole plugs.

WARNING

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Whirlpool WGFD293 Instruction Manual Page 31

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