Carrier 58CU0A Series Installation, Start-up, Operating And Service And Maintenance Instructions

Carrier 58CU0A Series Installation, Start-up, Operating And Service And Maintenance Instructions Manual pdf 39 page image

39CLEANING HEAT EXCHANGERThe following steps should be performed by a qualifiedservice agency:NOTE: If the heat exchangers get a heavy accumulation of sootand carbon, they should be replaced rather than trying to cleanthem thoroughly. A heavy build--up of soot and carbon indicatesthat a problem exists which needs to be corrected, such asimproper adjustment of gas valve outlet pressure, insufficient orpoor quality combustion air, incorrect size or damaged orifice(s),improper gas, or a restricted heat exchanger. Action must be takento correct the problem.If it becomes necessary to clean the heat exchangers because ofdust or corrosion, proceed as follows:1. Turn OFF gas and electrical power to furnace.2. Remove outer access door.3. Disconnect vent connector from furnace vent elbow.4. Disconnect wires to the following components. Markwires to aid in reconnection of (be careful when discon-necting wires from switches because damage may occur):a. Inducer motorb. Transducerc. Limit over--temperature switchd. Gas valvee. Hot surface ignitorf. Flame--sensing electrodeg. Burner thermal switchh. DSS Draft Safeguard5. Remove screws that fasten the inducer cover assembly tothe cell panel. Be careful not to damage the collector box.Inducer assembly and elbow need not be removed fromcollector box.6. Disconnect gas supply line from gas valve.7. Remove screws that attach the burner assembly to the cellpanel. The gas valve and burners tube need not be re-moved from burner box.NOTE: Be very careful when removing burner assembly toavoid breaking ignitor.8. Remove insulation assembly from burner tube inlets.NOTE: Proper use of Personal Protective Equipment (PPE)must be followed, including safety glasses, gloves, and dust maskwhen removing and reinstalling the heat exchanger insulationassembly.9. Using field--provided large caliber rifle cleaning brush,36--in. (914 mm) long steel spring cable, a variable speed,reversible electric drill, and vacuum cleaner, clean cells asfollows:NOTE: The materials needed in item 9. can usually bepurchased at local hardware stores.a. Remove metal screw fitting from wire brush to allow in-sertion into cable.b. Insert the twisted wire end of brush into end of springcable, and crimp tight with crimping tool or crimp bystriking with ball--peen hammer. TIGHTNESS IS VERYIMPORTANT.A180230Fig. 43 -- Ignitor Position(1.) Attach variable--speed, reversible drill to the end ofspring cable (end opposite brush).(2.) Insert brush end of cable into the outlet opening ofcell and slowly rotate with drill. DO NOT forcecable. Gradually insert cable into upper pass of cell.(See Fig. 44)(3.) Work cable in and out of cell 3 or 4 times to obtainsufficient cleaning. DO NOT pull cable with greatforce. Reverse drill and gradually work cable out.(4.) Insert brush end of cable in burner inlet opening ofcell, and proceed to clean two lower passes of cellin same manner as upper pass.(5.) Repeat foregoing procedures until each cell infurnace has been cleaned.(6.) Using vacuum cleaner, remove residue from eachcell.(7.) Using vacuum cleaner with soft brush attachment,clean burner assembly.(8.) Clean flame sensor with fine steel wool.(9.) Reinstall the insulation assembly.NOTE: If insulation assembly is damaged, do not attempt torepair, must be replaced with insulation kit.NOTE: Proper use of Personal Protective Equipment (PPE)must be followed, including safety glasses, gloves, and dust maskwhen removing and reinstalling the heat exchanger insulationassembly.(10.) Reinstall burner assembly.10. Remove old sealant from cell panel and collector boxflange.11. Spray releasing agent on the heat exchanger cell panelwhere inducer cover assembly contacts cell panel.NOTE: A releasing agent such as cooking spray or equivalent(must not contain corn or canola oil, aromatic or halogenatedhydrocarbons or inadequate seal may occur) and RTV sealant(G.E. 162, 6702, or Dow--Corning 738) are needed beforestarting installation.NOTE: DO NOT substitute any other type of RTV sealant.12. Apply new sealant to flange of collector box and attach tocell panel using existing screws, making sure all screwsare secure.13. Reconnect wires to the following components. (Useconnection diagram on wiring label, if wires were notmarked for reconnection locations.):a. Inducer motor