7
g.
Wiring materials located in the return duct system shall
conform to Articles 300-22 of the National Electrical
Code (ANSI C1/NFPA-70).
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.
For floor return systems, the manufactured home manu-
facturer shall affix a prominent marking on or near the
appliance where it can be easily read when the closet
door is open. The marking shall read:
k.
Air conditioning systems may require more duct, register
and open louver area to obtain necessary airflow. Use
NORDYNE’s certiduct program to determine proper
duct size for A/C.
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.
Before installing an air conditioner system, consult home
manufacturer for duct system maximum capacity. Location,
size, and number of registers should be selected on the basis
of best air distribution and floor plan of the home.
Table 3. Roof Jack Assemblies
CAUTION:
HAZARD OF ASPHYXIATION: Do not cover or
restrict return air opening.
!
3. VENTING AND COMBUSTION AIR
ROOF JACK SELECTION
Note: Install only Roof Jack Assemblies listed in Table 3 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 1).
b.
Determine ceiling height and subtract height of furnace.
(See Dimension “B” in Figure 1).
c.
Add dimensions A + B (and X from Table 3 and Figure 2
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 3.
ROOF JACK TROUBLE SHOOTING
The roof jack assembly is a telescoping type assembly (see
selection) that is made up of a pipe within a pipe construction.
The inner pipe (5”) is for the flue gases to exit the home. The
outer pipe (8”) is using the space in-between the 5” and 8” pipe
for combustion air. If the furnace is smothering itself out, after
a short time, on natural draft models, or pressure switch does
not make contact on M1M model, slide up air inlet a few inches
and check for debris in pipe. Clean out and check complete
flue assembly for blockage. On new homes make sure no
building materials fell in the top (air inlet or exhaust). Also
remove top and make sure no seams have opened up on roof-
jack assembly. On the M1G furnace (natural draft model) the
air inlet limit tripping is caused from a unbalanced draft, which
means the air inlet becomes a better flue than the flue itself.
Check-out Procedure:
Is furnace filter clean?
If furnace is installed in closet, what is the louver open area?
The installation instructions state the minimum open area
required is 235 sq. in., or 390 sq. in. for 5 ton.
Inspect roof-jack for internal blockage.
Inspect inside of upper combustion air box for debris.
With burner removed, reach inside lower air box into com-
bustion air chute to check for debris (insulation, roofing
material, drywall, etc.) and look in the bottom of the heat
exchanger for debris.
S
S
AW
T
27 47 - 2
AW= ALL WEATHER
FLASHING
PITCH/12" RISE
0=FLAT
2=2.5/12
4=4/12
MIN. ADJ.
LENGTH
F=
S=
FLAT FLASHING
SLANT FLASHING
TYPE:
BLANK=NON-TRANSIT
T= TRANSIT MODE
MAX. ADJ.
LENGTH
FLUE STEEL TYPE
A= ALUMINIZED
S=STAINLESS
Approx. Length
Model Number
Below Flashing
(F,S)AW(T)1523-(0,2,4)(A,S)
15" - 23"
(F,S)AW(T)2135-(0,2,4)(A,S)
21" - 35"
(F,S)AW(T)2747-(0,2,4)(A,S)
27" - 47"
(F,S)AW(T)3563-(0,2,4)(A,S)
35" - 63"
(F,S)AW(T)5195-(0,2,4)(A,S)
51" - 95"
