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

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Carrier 58MVP Installation, Start-up, And Operating Instructions Manual Manual pdf 35 page image

a. Obtain average yearly heat value for local gas supply.b. Obtain average yearly specific gravity for local gas supply.c. Verify the furnace model. Table 11 can only be used formodel 58MVP Furnaces.d. Find natural gas heat value and specific gravity in Table 11.e. Follow heat value line and specific gravity line to point ofintersection to find orifice size and manifold pressuresettings for proper operation at given natural gas condition.EXAMPLE:Heat value = 1010 Btu/cu ftSpecific gravity = 0.62Therefore: Orifice No. 44* with manifold pressure 3.3-in.wc for high heat and 1.4-in. wc for low heat.* Furnace is shipped with No. 45 orifices. In this exampleall main burner orifices must be changed and the manifoldpressure adjusted.f. Check and verify orifice size in furnace. NEVER ASSUMETHE ORIFICE SIZE; ALWAYS CHECK AND VERIFY.g. Proceed to item 3 to adjust manifold pressure.h. Check input rate by clocking meter as described in item 2.2. Determine natural gas input rate by clocking gas meter andadjusting manifold pressure per item 3.NOTE: Be sure all pressure tubing, combustion-air and ventpipes, and burner enclosure front are in place when checking inputby clocking the gas meter.a. Obtain average yearly heat value for local gas supply.NOTE: Be sure heating value of gas used for calculations iscorrect for your altitude. Consult local gas utility for altitudeadjustments of gas heating value.b. Turn off all other gas appliances and pilots.c. Start furnace and let run for 3 minutes.d. Measure time (in sec) for gas meter test dial to complete 1revolution.e. Refer to Table 12 for cubic ft of gas per hr.f. Multiply gas rate (cu ft/hr) by heating value (Btu/cu ft).Obtain heating value from local gas utility.EXAMPLE: Btu heating input = Btu/cu ft X cu ft/hrHeating value of gas = 1010 Btu/cu ftTime for 1 revolution of 2-cu-ft dial = 72 secGas rate = 100 cu ft/hr (from Table 12)Btu heating input = 100 X 1010 = 101,000 BtuhIn this example, the orifice size and manifold pressureadjustment is within ±2 percent of the furnace input rate.g. Measured gas input must not exceed gas input on unitrating plate.NOTE: High altitude—Gas input on rating plate is for altitudesup to 2000 ft. Ratings for altitudes over 2000 ft must be 4 percentless for each 1000 ft above sea level. To obtain the adjustedaltitude rating, adjust the manifold pressure (see item 3) andreplace the main burner orifices as needed. Refer to NFGCAppendix F, Table F-4 for proper orifice sizing at high altitudes.NOTE: In Canada, from 2000 to 4500 ft above sea level, deratethe unit 10 percent from the Conversion Station.Fig. 44—Inducer Housing Drain TubeA94208Fig. 45—Filling Condensate TrapA9420935