Carrier 58DR - Manual (Page 6)

B. Installation on a combustible floor
1. Read Installation Instructions packaged with acces­
sory combustible floor base.
2. Cut eind frame hole in floor per dimensions listed in
Installation Instructions packaged with combustible
floor base. If this requires cutting of a floor joist, tie
ends of cut joist into adjacent joists so that proper
floor support will be maintained.
3. Assemble and install downflow subbase per instruc­
tions packaged with subbase.
4. When completed, subbase, plenum, and furnace (or coil
casing when used) should be installed as shown in
Fig. 5.
VI. ELECTRICAL CONNECTIONS
A. 115-Volt Wiring
NOTE:
Refer to “Procedures for Natural-Draft Gas Fur­
naces” (packaged with the equipment) for additional
information.
A CAUTION
Do not connect aluminum wire between disconnect
switch emd furnace. Use only copper conductors.
See Fig. 8 for wiring diagram showing the proper field 115-
and 24-volt wiring.
Use a separate fused branch electrical circuit containing a
properly sized fuse or HACR-type circuit breaker for this
furnace. A disconnecting means must be located within
sight from, and readily accessible to, the furnace. In some
areas, the unit door switch may qualify as the disconnecting
A WARNING
The cabinet must have an uninterrupted or unbroken
ground according to National Electrical Code, ANSI/
NFPA 70-1987, or local codes to minimize personal
injury if an electrical fault should occur. This may con­
sist of electrical wire or conduit approved for electrical
ground when installed in accordance with existing elec­
trical codes. Do not use gas piping as an electrical
ground. A failure to adhere to this warning can result in
an electrical shock, fire, or death.
If 115-volt wiring to the unit is encased in a nonmetaUic
sheath, connect the incoming ground wire to the grounding
wire inside the furnace J-box. If metallic conduit is used, it
win serve as the ground.
B. 24-Volt Wiring
Make field 24-volt connections at the 24-volt terminal strip.
See Fig. 8.
NOTE: Use AWG No. 18 “color-coded” copper thermostat
wire for lengths up to 100 ft. Above 100 ft, use AWG No. 16
wire.
IMPORTANT: The thermostat heat anticipation must be set
to match the amp draw of the gas valve and electrical com­
ponents in the R-W circmt. Accurate amp draw readings
can be obtained at thermostat subbase terminals R & W.
Fig. 6 illustrates an easy method for obtaining the actual
amp draw.
The room thermostat should be located where it will be m
the natural circulation path of room air. Avoid locations
where the thermostat would be exposed to cold-air infiltra­
tion, drafts from windows, doors, or other openings leading
to the outside, or exposure to air currents from warm- or
cold-air registers; or to exposure where the natural circula­
tion of the eiir is cut off—such as behind doors, above or
below mantels, shelves, etc.
The thermostat should not be exposed to heat from nearby
fireplaces, radios, televisions, lamps, or rays from the sun.
Nor should the thermostat be mounted on a wall containing
pipes or warm-edr ducts, or a flue or vent that could affect
its operation and prevent it from properly controlling the
room temperature. Any hole in the plaster or panel through
which the wires pass from the thermostat should be ade­
quately sealed with suitable material to prevent drafts from
affecting the thermostat.
C. Blower Control Center
Each furnace features a printed-circuit control center. This
will aid the installer and serviceman when installing and
servicing the unit. See Fig. 7. A 24-volt terminal board is
marked for easy connection of field wiring.
VII. SEQUENCE OF OPERATION
NOTE: The wiring diagrams shown in Figs. 9 and 10 cover
heating/coofing units.
A. Heating
Gas and electrical supplies must be turned on at the
furnace.
NOTE: When power is apphed to heat relay coU HFR in the
control circuit, the normally-closed contacts in the blower
circuit wUl open.
1. White Rodgers 36E Gas Valve (IID Models). See Fig. 9.
When the thermostat “calls for heat,” the control circuit is
closed between terminals R and W. Power from transformer
TRAN through fusible link FL, hmit switches LS & ALS
and vent safety shut-off switch VSSS, energizes the pilot
valve part of automatic gas valve GV and pilot igniter PI.
The pilot valve opens, permitting gas flow to the pilot
burner where it is ignited.
The pilot valve portion of automatic gas valve GV has a
“pick” solenoid coil and latching “hold” device. The “pick”
coU must be energized to open the pilot valve, but only the
“hold” device must be energized to keep it open.
The “hold” device varies with the gas valve design used on
the furnace. It could be an internal pressure switch in series
with the “pick” solenoid coil, an internal electrical resistor
in series with the solenoid “pick” coU, or a separate electri­
cal solenoid coil.
When the pilot flame is estabhshed, safety pilot SP switches
its contacts in approximately 40 to 60 seconds, energizing
the main valve portion of gas valve GV and deenergizing
safety pilot igniter SP and the “pick” coil of the pilot sole­
noid portion in gas valve GV. The pilot valve is held open by
the “hold” device within gas valve GV.
The main valve portion of gas valve GV has a delayed open­
ing operator that opens within 6 to 15 seconds after it is
energized, permitting gas flow to the main burners where
the gas is ignited by pilot SP.
2. Honeywell VR800A and VR8200H Gas Valves (Match-
Lit Models). See Fig. 10
The furnace pilot must be ht to energize the thermal magnet
circuit of gas valve GV, thus permitting gas flow to the
remedning portion of the valve.
When the thermostat “calls for heat,” the control circuit is
closed between terminals R and W. Power from transformer
TRAN through fusible linkn FL, hmit switch LS & ALS and
vent safety shutoff switch VSSS energizes gas valve GV,
causing the valve to open and permitting gas flow to the
main burners, where it is ignited by the phot.