Start-up. adjustment and safety check, Sequence of operation – Carrier 58GS User Manual

Page 8

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BOTTOM CLOSURE PANEL — When the side

inlet is used, the bottom opening must be properly
sealed by installing a bottom closure panel shipped
under the filter in each furnace. To install the
bottom closure panel, perform the following steps:

After filter has been installed for side return, re
move bottom closure panel from furnace.

With furnace either tilted or raised, install panel
in opening on bottom of furnace, making certain

that locating tabs rest securely against sides

of cabinet. See Fig. 9.

WARNING: Never operate unit without a iiiter
or with filler acce.ss door removed-

eorroM

aosu!^ PANEL

LOCATING TASS

Fig. 9 — Installing Bottom Closure Panel

START-UP. ADJUSTMENT AND

SAFETY CHECK

Sequence of Operation

HEATING — Sizes 050 thru 150 (BDP 646AW gas

valve)

TIME (sec)*

ACTION

“”45'’

11b

Thermostat calls for heat. The control circuit be
tween R and W is closed: power from transformer
simultaneously opens solenoid of pilot gas valve
(inside main gas valve) and energizes spark

igniter

PiTot^as ignites

TTlof coritacTslnbffnaTly closed) open.'Spark

igniter ceases to spark

Pilot contacts (normally open) close, energizing
heat motor in main gas valve and solid-state

timing circuit in printed circuit control centejr^______

Heat motor opens main gas valve; main Burners
ignite from pilot flame
SoHd^itife tirning'cnxuiUswitches iti contacts

and blower motor starts

Thermostat is satisfied. Circuit between R and W
is broken; automatic gas valve is de-energized,
closing solenoid valve Solid-state timing circuit

is de-energized

T^in gas "valvelmd pilot valve close, extinguishing

flame

Piiot safety contacts open.

PIloTcontacts cioseTready for new cycle Solid-
state timing circuit switches its contacts, stopping
blower motor

‘Times are approximate: variance ±20%

HEATING — Size 175 (Essex 242 gas valve)

TIME (sec)*

ACTION

Thermostat calls for heat, power from transformer
simultaneously opens solenoid of pilot gas valve
(inside main gas valve) and energizes spark
igniter Solid-state timing circuit is energized

Pilot gas ignites
Once pilot flame is proven electrically, igniter
ceases to spark, main gas valve opens and mam
burners ignite from pilot flame

Solid-state timing circuit switches its confacfs
and blower motor starts

Thermostat is satisfied Pilot and main gas valves
are de-energized Solid-state timing circuit is
de-energized

Pilot and main burners are extingmsh^_ ____________

Solid-state timing circuit switches its contacts,
stopping blower motor

‘Times are approximate, variance ±20%

LIMIT SWITCH — If the furnace overheats for
any reason, the limit switch will open, breaking the

circuit to automatic gas valve, so the gas valve
closes immediately. Without low-voltage current
applied to heat relay, its normally closed contacts
energize blower motor.