035-20499-001 Rev. B (1004)
6
Unitary Products Group
IMPORTANT:
If an external mounted filter rack is being used see the
instructions provided with that accessory for proper hole cut size.
SECTION III: FILTERS
FILTER INSTALLATION
All applications require the use of a filter. A high velocity filter and a side
return filter rack are provided for field installation. Replacement filter
size is shown in Table 4.
Filters must be installed external to the furnace cabinet.
DO NOT
attempt to install filters inside the furnace.
SIDE RETURN - FILTER INSTALLATION
Locate and mark the side return opening. Refer to Figure 1 for dimen-
sions of the cutout.
Install the side filter rack following the instructions provided with that
accessory. If a filter(s) is provided at another location in the return air
system, the ductwork may be directly attached to the furnace side
panel.If not provided with the furnace, an accessory filter rack is avail-
able for mounting the filter external to the cabinet.
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 shown in Figure 1.
SECTION IV: GAS PIPING
GAS SAFETY
IMPORTANT:
Plan your gas supply before determining the correct gas
pipe entry. Use 90-degree service elbow(s), or short nipples and con-
ventional 90-degree elbow(s) to enter through the cabinet access holes.
FIGURE 2:
Furnace Base Rectangular Blockoff Panel
TABLE 4:
Filter Sizes
Input / Output
BTU/H (kW)
CFM
(m
3
/min)
Cabinet
Size
Side Return
Filter in. (cm)
Bottom Return
Filter in. (cm)
40/38/1200
(11.7/10.8)
1200
(34)
A
16 x 25
(41 x 64)
14 x 25
(36 x 64)
60/56/1200
(17.57/16.40)
1200
(34)
B
16 x 25
(41 x 64)
16 x 25
(41 x 64)
80/75/1200
(23.42/21.96)
1200
(34)
B
16 x 25
(41 x 64)
16 x 25
(41 x 64)
80/75/1600
(23.42/21.96)
1600
(45)
C
16 x 25
(41 x 64)
20 x 25
(51 x 64)
100/93/2000
(29.28/27.25)
2000
(57)
C
16 x 25
(41 x 64)
20 x 25
(51 x 64)
120/112/2000
(35.14/32.80)
2000
(57)
D
(2) 16 x 25
(2) (41 x 64)
22 x 25
(56 x 64)
All installations must have a filter installed.
Toe Plate
Removable Rectangular
Base Panel.
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 PSI (14" w.c. (3.48 kPa). Pressures exceeding
0.5 PSI (14” w.c. (3.48 kPa) at the gas valve will cause damage 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.
FIGURE 3:
Gas Valve
INLET
WRENCH
BOSS
INLET
PRESSURE
PORT
ON OFF
SWITCH
LOW STAGE REGULATOR
ADJUSTMENT
OUTLET
OUTLET
PRESSURE
PORT
VENT
PORT
HIGH STAGE REGULATOR
ADJUSTMENT
CHECKING THE GAS PRESSURES
1.
The pressure ports on the gas valve are marked OUT P and IN
P.
2.
The manifold pressure must be taken at the port marked OUT P.
3.
The inlet gas supply pressure must be taken at the port marked
IN P.
4.
Using a 3/32” (0.2 cm) Allen wrench, loosen the set screw by
turning it 1 turn counter clockwise. DO NOT REMOVE THE
SET SCREW FROM THE PRESSURE PORT.
5.
Push one end the 3/8” (0.9 cm) ID flexible tubing over the pres-
sure port so that the body of the port is inside the tubing.
6.
Use a reducer connector to connect the 3/8” (0.9 cm) ID flexible
tube to a 1/4” (0.6 cm) ID flexible tube that is connected to a "U”
tube manometer or digital pressure measuring equipment.
IMPORTANT:
The inlet gas pressure operating range table specifies
what the minimum and maximum gas line pressures must be for the
furnace to operate safely. The gas line pressure
MUST BE
•
7” W.C. (1.74 kPA) for Natural Gas
•
11” W.C. (2.74 kPA) for Propane (LP) Gas
in order to obtain the BTU input specified on the rating plate and/or
the nominal manifold pressure specified in these instructions and on
the rating plate.
TABLE 5:
Inlet Gas Pressure Range
INLET GAS PRESSURE RANGE
Natural Gas
Propane (LP)
Minimum
4.5” W.C. (1.12 kPa)
8.0” W.C. (1.99 kPa)
Maximum
10.5” W.C. (2.61 kPa)
13.0” (3.24 kPa) W.C.
