5894307-UIM-B-0920
Johnson Controls Ducted Systems
7
Notes:
Air velocity through throwaway filters must not exceed 300 ft/min (91.4 m/min). All
velocities over this require the use of high velocity filters.
Do not exceed 1800 CFM using a single side return and a 16 x 25 filter. For CFM
greater than 1800, you can use two side returns, or one side and the bottom, or
one side return with a transition to allow use of a 20 x 25 filter.
SIDE RETURN
Locate the L-shaped corner locators. These indicate the size of the cut-
out to be made in the furnace side panel. See Figure 7.
Install the side filter rack following the instructions provided with that
accessory. If filters are provided at another location in the return air sys-
tem, the ductwork can be directly attached to the furnace side panel.
HORIZONTAL FILTERS
Any branch duct (rectangular or round duct) attached to the plenum
must attach to the vertical plenum before the filter. The use of straps
and/or supports is required to support the weight of the external filter
box.
SECTION IV: GAS PIPING
GAS SAFETY
GAS PIPING INSTALLATION
Correctly sized wrought iron, approved flexible or steel pipe must be
used when making gas connections to the unit. If local codes allow the
use of a flexible gas appliance connection, always use a new listed con-
nector. Do not use a connector that has previously serviced another gas
appliance.
Some utility companies or local codes require pipe sizes larger than the
minimum sizes listed in these instructions and in the codes. The furnace
rating plate and the instructions in this section specify the type of gas
approved for this furnace - only use those approved gases. The instal-
lation of a drip leg and ground union is required. See Figure 10.
For left side supply gas pipe arrangement, two 1/2 in. elbows and two
1/2 in. x 1-1/2 in. pipe nipples must be used. The arrangement shown in
Figure 9 aligns entrance hole in furnace casing with supply gas pipe.
Furnace casing does not support installations completed using street-
elbows.
Table 3:
Recommended Filter Sizes (High Velocity 600 FPM)
CFM (m³/min)
Cabinet Size
Side (in.)
Bottom (in.)
1200 (34.0)
B
16 x 25
16 x 25
1600 (45.3)
C
16 x 25
20 x 25
2000 (56.6)
C
(2) 16 x 25
20 x 25
Figure 7:
Side Return Cutout Markings
IMPORTANT:
Some accessories such as electronic air cleaners and
pleated media may require a larger side opening. Follow the instruc-
tions supplied with that accessory for side opening requirements. Do
not cut the opening larger than the dimensions for the Optional
Return Air Cutout shown in Figure 6.
DANGER
An overpressure protection device, such as a pressure regulator,
must be installed in the gas piping system upstream of the furnace
and must act to limit the downstream pressure to the gas valve so it
does not exceed 0.5 psig (14 in. W.C., 3.48 kPa). Pressures exceed-
ing 0.5 PSI (14 in. W.C., 3.48 kPa) at the gas valve will cause dam-
age to the gas valve, resulting in a fire or explosion or cause damage
to the furnace or some of its components that will result in property
damage and loss of life.
Front of
Furnace
Corner
Markings
Side of
Furnace
!
Figure 8:
Gas Valve
IMPORTANT:
Plan the gas supply routing before determining the
correct gas pipe entry. Use 90° conventional elbows and short pipe
nipples to enter through the cabinet access holes.
Figure 9:
Left Side Supply Gas Pipe Arrangement
Inlet
Wrench
Boss
Inlet
Pressure
Port
ON
OFF
On/Off Switch
(Shown in ON position)
Main Regulator
Adjustment
Outlet
Outlet
Pressure
Port
Vent Port
A1122-001
TO
GAS
SUPPLY
GAS
VALVE
½" x 1½"
PIPE NIPPLE
90° ELBOW
½" x 1½"
PIPE
NIPPLE
90°
ELBOW
