272317-UIM-A-0407
Unitary Products Group
7
NOTES:
1. Air velocity through throwaway type filters may not exceed 300 feet per minute. All velocities over this require the use of high velocity filters.
2. Air flows above 1800 CFM require either return from two sides or one side plus bottom.
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.
GAS PIPING INSTALLATION
Properly 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. Refer to Figure 3.
IMPORTANT:
An accessible manual shutoff valve must be installed
upstream of the furnace gas controls and within 6 feet (1.8 m) of the fur-
nace.
The furnace must be isolated from the gas supply piping system by
closing its individual external manual shutoff valve during any pressure
testing of the gas supply piping system at pressures equal to or greater
than 1/2 psig (3.5 kPa).
Gas piping may be connected from either side of the furnace using any
of the gas pipe entry knockouts on both sides of the furnace. Refer to
Figure 1 dimensions.
The inlet to the gas valve lines up directly with the opening in the left
side of the furnace casing. To line up with the opening in the right side
of the casing, two street ells should be used.
TABLE 4:
Recommended Filter Sizes
Input
BTU/H (kW)
CFM
(m
3
/min)
Cabinet
Size
Side Return
Filter in. (cm)
Bottom Return
Filter in. (cm)
40 (11.7)
1200 (34.0)
A
16 x 25 (41 x 64)
14 x 25 (36 x 64)
60 (17.8)
1200 (34.0)
B
16 x 25 (41 x 64)
16 x 25 (41 x 64)
80 (23.4)
1200 (34.0)
B
16 x 25 (41 x 64)
16 x 25 (41 x 64)
80 (23.4)
1600 (45.3)
C
16 x 25 (41 x 64)
20 x 25 (51 x 64)
100 (29.3)
1600 (45.3)
C
16 x 25 (41 x 64)
20 x 25 (51 x 64)
100 (29.3)
2000 (56.6)
C
16 x 25 (41 x 64)
20 x 25 (51 x 64)
120 (35.1)
2000 (56.6)
D
(2) 16 x 25 (2) (41 x 64)
22 x 25 (56 x 64)
All installations must have a filter installed.
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 exceed-
ing 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 2:
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
FIGURE 3:
Gas Piping
Never apply a pipe wrench to the body of the gas valve when
installing piping. A wrench must be placed on the octagonal hub
located on the gas inlet side of the valve. Placing a wrench to the
body of the gas valve will damage the valve causing improper oper-
ation and/or the valve to leak.
EXTERNAL MANUAL
SHUTOFF VALVE
TO GAS
SUPPLY
TO GAS
SUPPLY
GROUNDED JOINT UNION
MAY BE INSTALLED
INSIDE OR OUTSIDE UNIT.
DRIP
LEG
