548267-YIM-C-0211
8
Unitary Products Group
5.
When attaching the flex duct to the return air box, secure
the duct collar and return box collar together with at least
three (3) sheet metal screws and seal with duct tape.
6.
Set the return air box, with flex duct attached, back into the
floor opening.
7.
Fasten the return air box securely to the floor with screws
or nails.
8.
Seal fiber under board hole around flex duct.
For ease of installation of the flexible ductwork, it is
recommended that as much work as possible be done outside
the underneath area of the manufactured home. Accurate
measurements are required. Plan the ducting configuration well
and double check the measurements.
Check the intended routing and length required of the flexible
duct.
Remember, each slight change in direction of the duct add
static resistance and reduces airflow.
Keep flexible ducts straight and short. Wide sweeping bends
should be used when turns are necessary, not sharp corners or
angles.
1.
When return air grille box is installed, run the duct to the
return air inlet flange on the unit.
2.
Cut the duct to the required length using a knife, or tin
snips, and cut the helical wire with a wire cutter.
3.
Insert a stub collar in the raw end of the duct and tape
securely in place.
4.
Make sure the duct is not stretched tight and does not have
kinks from excessive length after installation.
5.
Attach the duct end, with the stub collar, to the air
conditioner return air flange with screws and duct tape
sealing the duct cover securely.
Wye Insulation
It is necessary to field fabricate and install an insulation jacket
for the Wye. Insulation will prevent loss of capacity especially
where the gain or loss is critical in a borderline installation. See
Figures 6 and 7.
1.
Use “faced” batt insulation material.
2.
Place the insulation on the topside of the Wye, with the
faced or vinyl side out.
3.
Tape to insulation placed on bottom of Wye and tape
together “diaper style”.
4.
Make sure a tight bond is obtained and attach to flexible
duct sleeves with tape.
5.
Tape insulation to return air opening flange, airtight.
NOTE:
The insulation should not be compressed around the
Wye. This defeats the purpose of the insulation.
Figure 6: Wye Installation (Outlet)
Grille
Filter
Return Box
2
1
Damper*
Damper*
12” Duct Connectors
Flex Duct
Flex Duct
12 x12 x12
WYE
4
”
WYE Insulation Recommended
for Greater Efficiency and
Performance of Unit.
May use duct connector without
damper if no interior furnace or air
handler is connected to duct system.
Return duct may be oversized
to accommodate the maximum
8” static pressure
Inlet
Flange
Outlet
Flange
1
2
