Carrier 58GFA Installation, Starting-up And Operation Manual

Also see for INDUCED COMBUSTION FURNACES 58GFA: Installation, start-up, and operating instructions Service and maintenance instructions Service and maintenance instructions Installation, start-up, and operating instructions User's information manual

Contents

Carrier 58GFA Installation, Starting-up And Operation Manual Manual pdf 8 page image

This furnace is equipped with a fuse link in the gas controlarea. The fuse link will open and shut off power to the gasvalve if a flame rollout or overheating condition occurs in thegas control area. DO NOT bypass the fuse link. Call yourservice dealer to correct inadequate combustion-air supplyproblem and replace fuse link.Before operating the furnace, check each manual reset switch forcontinuity. If necessary, press the button to reset the switch.The blower compartment door must be in place to complete the115-v circuit to the furnace.SEQUENCE OF OPERATION — Using the schematic diagramshow in Fig. 10, follow the sequence of operation through thedifferent modes.NOTE: When the blower door is in place, 115v is suppliedthrough blower door interlock switch ILK to heating fan relayHFR, induced draft relay IDR, and transformer TRAN. Trans-former TRAN energizes the safety circuit containing fuse link FLand limit switch LS to energize R.The furnace pilot must be lit so the thermocouple energizes thethermal magnet circuit of gas valve GV, which permits gas flow tothe remaining portion of the valve.1. Heating modea. When the wall thermostat "calls for heat" the R-W circuitcloses. This closed circuit supplies power to the 24-v safetycircuit containing automatic reset limit switch LS and fuselink FL.b. The inducer-motor relay coil IDR is energized. Inducermotor relay contacts in the 115-v circuit close, startinginducer motor IDM. Simultaneously, another set of con-tacts in inducer-motor relay IDR close in the 24-v circuitand lock-in until the R-W circuit or safety opens.c. As inducer motor IDM comes up to speed, pressure switchPRS actuates and supplies power through manual resetdraft safeguard switch DSS. Both solenoid coils in gasvalve GV are energized, causing the valve to open andpermitting gas flow to the main burners, where it is ignitedby the pilot.d. Simultaneously, solid-state time-delay circuit in the blowercontrol center is energized. Approximately 45 sec after theR-W circuit is closed, heating fan relay coil HFR isenergized, closing the 115-v contacts of heating fan relayHFR, and starting blower motor BLWM on heating speed.EAC terminals energize with 115v when the blower isoperating on either heating or cooling speed.e. When the thermostat is satisfied, the R-W circuit is broken,de-energizing both solenoid coils of gas valve GV and thesolid-state time-delay circuit for the heating fan relay HFR.The gas flow to the main burners immediately stops.Approximately 120 sec (or 180 sec depending on theblower off time selected) after main burners are extin-guished, heating fan relay HFR is de-energized and blowermotor BLWM stops. The blower off delay can be perma-nently changed to 180 sec by cutting the resistor. (See Fig.9.)f. If the pilot flame is extinguished, the thermocouple nolonger energizes the thermal magnet circuit of gas valveGV. Gas flow to the pilot and main burners ceases until thepilot is manually relit.NOTE: When gas valve GV is energized, R-W circuit is closed.After a power interruption, the gas valve closes within 7 sec andthe furnace skips the blower on delay and immediately starts theblower.2. Cooling modeWhen the wall thermostat "calls for cooling" the R, G, and Ycircuits close. Simultaneously, the R-Y circuit starts theoutdoor condensing unit, the R-G circuit energizes coolingrelay coil CFR, and heating fan relay coil HFR. The normallyopen contact of heating fan relay HFR and the normally opencontact of cooling relay CFR closes, energizing the coolingspeed of blower motor BLWM. The EAC terminals areenergized with 115v when the blower is operating on eitherheating or cooling speed.3. Continuous blower modeWhen the R-G circuit is made, the blower motor operates oncooling speed. During a "call for heat", the blower stops,allowing the furnace heat exchangers to heat up more quickly.When the blower motor comes back on it runs on heatingspeed. The blower reverts to continuous operation after theheating cycle blower off delay is completed.START-UP PROCEDURES — Check to be sure that all connec-tions have been properly made, then light the pilot using theprocedure outlined on the lighting/operation instructions labelattached to the furnace. However, when lighting the pilot for thefirst time, perform the following additional steps:1. Purge gas lines after all connections have been made andcheck for leaks.Fig. 9—Control CenterA95463SEC-2SEC-1GROUNDSCREWREQUIREDFU 3-AMPFUSEBLOWEROFF-DELAY24VACCOMMONCES0110074-01W Y1 R C GCOM PR-2 L2CFRLOHIHFRL1PR-1PL-112345678913IDR24-VAC COMMON24-VAC FUSE3-AMP ONLYBLOWEROFF-TIMEADJUSTMENT24-VACTHERMOSTATTERMINALSCOOLINGSPEED TAPTERMINALHEATINGSPEED TAPTERMINAL115-VACNEUTRALTERMINALS115-VACLINEVOLTAGE115-VACTRANSFORMER9-PINCONNECTORELECTRONICAIR-CLEANERTERMINALS24-VAC POWEREAC-2EAC-1SPARE-1SPARE-28→