035-20499-001 Rev. B (1004)
16
Unitary Products Group
Specially Engineered Installations
The above requirements shall be permitted to be waived where special
engineering, approved by the authority having jurisdiction, provides an
adequate supply of air for combustion, ventilation and dilution of flue
gases.
SECTION VII: CONDENSATE PIPING
The condensate drain connection is provided in the furnace for field
installation. It consists of a formed hose with a 1/2” (1.3 cm) NPT male
connection. A 1/2” (1.3 cm) FM x 3/4” (1.9 cm) PVC slip coupling is pro-
vided.
This drain hose may be installed to allow left or right side condensate
drain connection, refer to Figure 22. Cut the hose to allow for proper fit
for left or right exit. If necessary, trim the hose supplied to ensure that it
slopes downwards.
To install the drain hose assembly, remove the 7/8” (2.2 cm) knockout in
the side panel. Remove the conduit nut from the 1/2” (1.3 cm) male fit-
ting. Push the male fitting through the hole and reinstall the nut. The
use of the 3/4” (1.9 cm) PVC coupling is optional.
The condensate water will flow to the drain better if an open tee, or
short length of pipe is installed in the drain line, as shown in Figure 22.
IMPORTANT:
The condensate drain from the furnace may be con-
nected in common with the drain from an air conditioning coil if allowed
by local code.
IMPORTANT:
Condensate must be disposed of properly. Follow local
plumbing or wastewater codes. The drain line must maintain a 1/4" per
foot (0.635 cm per meter) slope to the drain.
CONDENSATE DRAIN
The condensate trap must be filled with water before putting the furnace
into operation. Perform the following procedures only after the conden-
sate trap has been properly piped to a drain connection using the pro-
cedure in this instruction.
The recommended procedure is as follows:
1.
Disconnect the condensate drain hose from the induced draft
blower discharge.
2.
Elevate this hose and fill with water using a funnel.
3.
Replace the condensate drain hose and clamps.
IMPORTANT:
If this procedure is not followed, the unit may not properly
drain on initial start up.
CONDENSATE DRAIN TERMINATION
DO NOT terminate condensate drain in a chimney, or where the drain
line may freeze. The line must terminate at an inside drain to prevent
freezing of the condensate and possible property damage.
DO NOT trap the drain line at any other location than at the condensate
drain trap supplied with the furnace.
A condensate sump pump MUST be used if required by local codes, or
if no indoor floor drain is available. The condensate sump pump must
be approved for use with acidic condensate.
CONDENSATE DRAIN TRAP AND DRAIN FREEZE
PROTECTION
Special precautions MUST be made if installing furnace in an area
which may drop below freezing. This can cause improper operation or
damage to the equipment. If the furnace is installed in an area that has
the potential of freezing, the drain line and the drain trap must be pro-
tected. Use a 3 to 6 watt per foot (0.003 to 0.006 kW per meter) at 115
vac, 40º F (4.4° C) self-regulating, shielded and waterproof heat tape.
Wrap the drain trap and the drain line with the heat tape and secure
with ties. Follow the heat tape manufacturer's recommendations.
SECTION VIII: SAFETY CONTROLS
CONTROL CIRCUIT FUSE
A 3-amp fuse is provided on the control circuit board to protect the 24-
volt transformer from overload caused by control circuit wiring errors.
This is an ATO 3, automotive type fuse and is located on the control
board.
BLOWER DOOR SAFETY SWITCH
This unit is equipped with an electrical interlock switch mounted in the
blower compartment. This switch interrupts all power at the unit when
the panel covering the blower compartment is removed.
Electrical supply to this unit is dependent upon the panel that covers the
blower compartment being in place and properly positioned.
ROLLOUT SWITCH CONTROLS
These controls are mounted on the burner box assembly. If the temper-
ature in the burner box exceeds its set point, the ignition control and the
gas valve are de-energized. The operation of this control indicates a
malfunction in the combustion air blower, heat exchanger or a blocked
vent pipe connection. Corrective action is required. These are manual
reset controls that must be reset before operation can continue.
PRESSURE SWITCHES
This furnace is supplied with two pressure switches, which monitor the
flow through the combustion air/vent piping system. These switches de-
energize the ignition control module and the gas valve if any of the fol-
lowing conditions are present. Refer to Figure 23 for tubing connec-
tions.
1.
Blockage of combustion air piping or terminal.
2.
Blockage of vent piping or terminal.
3.
Failure of combustion air blower motor.
4.
Blockage of condensate drain piping.
FIGURE 21:
Attic and Crawl Space Combustion Air Termination
Be sure to instruct the owner not to block this intake pipe.
FIGURE 22:
Condensate Piping
12”
MIN.
12” MINIMUM
BETWEEN BOTTOM
OF BELOW AND
ANY MATERIAL
OPEN
TEE
OPEN
TEE
RH
DRAIN
LH
DRAIN
Main power to the unit must still be interrupted at the main power
disconnect switch before any service or repair work is to be done to
the unit. Do not rely upon the interlock switch as a main power dis-
connect.
Blower and burner must never be operated without the blower
panel in place.
