Carrier 58MSA Installation, Start-up, And Operating Instructions Manual

Also see for 58MSA Series: Service and maintenance instructions User manual Instruction manual Installation, start-up, and operating instructions Installation, start-up, and operating instructions

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Carrier 58MSA Installation, Start-up, And Operating Instructions Manual Manual pdf 37 page image

NOTE: If orifice hole appears damaged or it is suspected to havebeen redrilled, check orifice hole with a numbered drill bit ofcorrect size. Never redrill an orifice. A burr-free and squarelyaligned orifice hole is essential for proper flame characteristics.d. Replace gas valve regulator adjustment screw cap.e. Replace burner enclosure front and verify adjusted gasinput rate using method outlined in item 3.f. Look through sight glass in burner enclosure and checkburner flame. Burner flame should be clear blue, almosttransparent. (See Fig. 41.)3. Verify natural gas input rate by clocking gas meter.NOTE: Be sure all pressure tubing, combustion-air and ventpipes, and burner enclosure front are in place when checking inputby clocking gas meter.NOTE: High-Altitude AdjustmentUnited StatesAt altitudes above 2000 ft, this furnace has been approved for a 2%derate for each 1000 ft above sea level. See Table 8 for deratemultiplier factor.EXAMPLE:100,000 Btuh input furnace installed at 4300 ft.Furnace Input Rateat Sea Level XDerateMultiplierFactor=Furnace Input Rateat InstallationAltitude88,000 X 0.91 = 80,080CanadaAt installation altitudes from 2000 to 4500 ft, this furnace must bederated 5% by an authorized Gas Conversion Station. To deter-mine correct input rate for altitude, see example above and use0.95 as derate multiplier factor.a. Turn off all other gas appliances and pilots.b. Start furnace and let operate for 3 minutes.c. Measure time (in sec) for gas meter test dial to complete 1revolution.d. Refer to Table 9 for cu ft of gas per hr.e. Multiply gas rate (cu ft/hr) X heating value (Btu/cu ft)using natural gas heating value from local gasutility/supplier.EXAMPLE:Btu heating input = Btu/cu ft X cu ft/hrHeating value of gas = 975 Btu/cu ftTime for 1 revolution of 2-cu ft dial = 70 secGas rate = 103 cu ft/hr (from Table 9)Btu heating input = 103 X 975 = 100,425 BtuhIn this example, the orifice size and manifold pressureadjustment is within ±2 percent of the furnace inputrate.SET TEMPERATURE RISETemperature rise must be within limits specified on unitrating plate. Recommended operation is at midpoint of rise orabove. Failure to follow this caution may result in condensingor overheating the heat exchangers.Determine and adjust air temperature rise as follows:1. Place thermometers in return and supply ducts as close tofurnace as possible. Be sure thermometers do not see heatexchanger so that radiant heat does not affect readings. Thispractice is particularly important with straight-run ducts.2. When thermometer readings stabilize, subtract return-air tem-perature from supply-air temperature to determine air tem-perature rise.DO NOT redrill orifices. Improper drilling (burrs, out-of-round holes, etc.) can cause excessive burner noise andmisdirection of burner flames. This can result in flameimpingement of burners and heat exchangers causing failures.A93059BURNERORIFICEFig. 41—Burner FlameA89020BURNER FLAMEBURNERMANIFOLDTable 8—Altitude Derate Multiplier for U.S.A.ALTITUDE(FT)% OFDERATEDERATE MULTIPLIERFACTOR FOR U.S.A*0—2000 0 1.002001—3000 4—6 0.953001—4000 6—8 0.934001—5000 8—10 0.915001—6000 10—12 0.896001—7000 12—14 0.877001—8000 14—16 0.858001—9000 16—18 0.839001—10,000 18—20 0.81* Derate multiplier factor is based on midpoint altitude for altitude range.37

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