Nordyne M1G Air Distribution Systems, Roof Jack Selection, Application Notes, Floor Cavity Sizes

h. Gas piping is not run in or through the return duct system.

i.Test the negative pressure in the closet with the air-circulating fan operating at high speed and the closet closed. The negative pressure is to be no more negative than minus 0.05 inch water column.

j.Air conditioning systems may require more duct register and open louver area to ob- tain necessary airflow. Use NORDYNE’s certiduct program to determine proper duct size for A/C.

8.AIR DISTRIBUTION SYSTEMS

For proper air distribution, the supply duct system must be designed so that the static pressure measured external to the furnace does not exceed the listed static pressure rating shown on the furnace rating plate.

Location, size, and number of registers should be selected on the basis of best air distribution and floor plan of the home.

!CAUTION:

HAZARD OF ASPHYXIATION: Do not cover or restrict return air opening.

9.ROOF JACK SELECTION

Note: Install only Roof Jack Assemblies listed in Table 5 on this heating appliance.

a.Determine depth of ceiling cavity from center of roof opening to center of ceiling opening. (See Dimension “A” in Figure 6.)

b.Determine ceiling height and subtract height of furnace. (See Dimension “B” in Figure 6.)

c.Add dimensions A + B (and X from Table 6 and Figure 7 if slant deck flashing is used). The total length of (A + B + X) must be within the minimum and maximum range of one of the Roof Jacks listed in Table 5.

APPLICATION NOTES:

a. FAW, FAWT, SAW and SAWT Series Roof Jacks with a 5" diameter inner vent pipe may be used with all models of M1 Series gas and oil furnaces.

b.F=Flat Flashing; flexes from 0/12 to 1/12 roof slope.

c.S=Slant Flashing. 2.5/12 Slope flexes from 1/ 12 to 4/12 roof slope, 4/12 flexes from 3/12 to 5/12.

d.Stainless steel roof jacks are available.

e.If the roof jack crown is covered or blocked with snow, the furnace will not operate prop- erly. If the home is located in regions where snow accumulation exceeds 7” (HUD snowload zones) use an external roof jack extension p/n 901937.

f.M1 furnaces may be used with roof jacks as tall as 170” (except M1M 056 & M1B 066 models, which are limited to 120”). An internal roof jack extension (p/n 901935 - 10”, p/n 903107 - 18”) can be used to increase roof jack height. All connections inside the home must be made below the ceiling.

These extensions are available as optional accessories and may be purchased through your NORDYNE distributor.

	USE SLANT DECK
IF ROOF PITCH IS:	FLASHING NO.	"X" FACTOR IS:
	"F Series Roof Jack
2" in 12"	903893 (2.5/12)	2-1/8"
2-1/2" in 12"	903893 (2.5/12)	2-1/2"
3" in 12"	903894 (3/12)	2-7/8"
3-1/2" in 12"	903894 (3/12)	3-1/4"
4" in 12"	903895 (4/12)	3-5/8"
"S" Series Roof Jack (2.5/12 Pitch only)
4-1/2" in 12"	903895 (2.5/12)	2-1/8"
5" in 12"	903895 (2.5/12)	2-1/2"
5-1/2" in 12"	903894 (3/12)	2-7/8"
6" in 12"	903894 (3/12)	3-1/4"
6-1/2" in 12"	903895 (4/12)	3-5/8"

Optional Deck Flashings for Flat and 2.5/12 Pitch

Roof Jacks.

(4/12 Pitch Roof Jacks not applicable.)

Table 6. Slant Deck Flashings

		Use Duct Connector
If "X" (Floor Cavity) is:		Model Part Number:
English	Metric (mm)	Finger Tab	Screw Down
7/8"	22	901987	904008
2"	51	901988	904009
4-1/4"	108	901989	904010
6-1/4"	159	901990	904011
8-1/4"	210	901991	904012
10-1/4"	260	901992	904013
12-1/4"	311	901993	904014

Table 7. Floor Cavity Sizes

8