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

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Carrier 58CVA Installation, Start-up, Operating And Service And Maintenance Instructions Manual pdf 29 page image

5. Verify furnace shut down by lowering thermostat settingbelow room temperature.6. Verify furnace restarts by raising thermostat setting aboveroom temperature.Step 3—AdjustmentsFurnace gas input rate on rating plate is for installations at altitudesup to 2000 ft. Furnace input rate must be within ±2 percent offurnace rating plate input.In the U.S.A., the input rating for altitudes above 2,000 ft. must bereduced by 4 percent for each 1,000 ft. above sea level. In Canada,input rating must be reduced by 10 percent for altitudes of 2,000ft. to 4,500 ft. above sea level. For altitudes above 5500 ft., afield-supplied high altitude pressure switch is required.1. Determine the correct gas input rate.In the U.S.:For installations below 2000 ft., refer to the unit rating plate.For installations above 2000 ft., multiply the input on therating plate by the de-rate multiplier in Table 7 for the correctinput rate.Table 7—ALTITUDE DERATE MULTIPLIER FORU.S.A.ALTITUDE(FT)PERCENTOF DERATEDERATE MULTIPLIERFACTOR FOR U.S.A.*0–2000 0 1.002001–3000 8–12 0.903001–4000 12–16 0.864001–5000 16–20 0.825001–6000 20–24 0.786001–7000 24–28 0.747001–8000 28–32 0.708001–9000 32–36 0.669001–10,000 36–40 0.62* Derate multiplier factor is based on midpoint altitude for altitude range.In Canada:At installation altitudes from 2000 to 4500 ft, this furnace must bederated 10 percent by an authorized Gas Conversion Station orDealer. To determine correct input rate for altitude, see exampleand use 0.90 as derate multiplier factor.EXAMPLE:88,000 BTUH INPUT FURNACE INSTALLED AT 4300 FT.Derate Furnace Input RateFurnace Input Rate X Multiplier = at Installationat Sea Level Factor Altitude88,000 X 0.90 = 79,2002. Determine the correct orifice and manifold pressure adjust-ment. All models in all positions except Low NOx models indownflow and horizontal positions us Table 10 (22,000 Btuhper burner.) Low NOx models in downflow or horizontalpositions must use Table 11 (21,000 Btuh per burner.)See input listed on rating plate.a. Obtain average yearly gas heat value (at installed altitude)from local gas supplier.b. Obtain average yearly gas specific gravity from local gassupplier.c. Find installation altitude in Table 10 or 11.d. Find closest natural gas heat value and specific gravity inTable 10 or 11.e. Follow heat value and specific gravity lines to point ofintersection to find orifice size and low-and high-heatmanifold pressure settings for proper operation.f. Check and verify burner orifice size in furnace. NEVERASSUME ORIFICE SIZE. ALWAYS CHECK ANDVERIFY.g. Replace orifice with correct size if required by Table 10 or11. Use only factory-supplied orifices. See EXAMPLE 2.22,000 Btuh per burner application use Table 10.EXAMPLE 2: (0–2000 ft altitude)Heating value = 1000 Btu/cu ftSpecific gravity = 0.62Therefore: Orifice No. 43*Manifold pressure: 3.7-in. wc for high-heat1.6-in. wc for low-heat* Furnace is shipped with No. 43 orifices. In this exampleall main burner orifices are the correct size and do not needto be changed to obtain proper input rate.3. Adjust manifold pressure to obtain low fire input rate.a. Turn gas valve ON/OFF switch to OFF.b. Remove manifold pressure tap plug from gas valve.c. Connect a water column manometer or similar device tomanifold pressure tap.d. Turn gas valve ON/OFF switch to ON.e. Move setup SW 1–2 on variable speed furnace control toON position. (See Table 6) to lock furnace in low-heatoperation.f. Manually close blower door switch.g. Jumper R and W/W1 thermostat connections on control tostart furnace.h. Remove regulator adjustment cap from low fire gas valvepressure regulators. (See Fig. 47.) and turn low-heatadjusting screw (5/64 hex Allen wrench) counterclockwise(out) to decrease input rate or clockwise (in) to increaseinput rate.NOTE: DO NOT set low-heat manifold pressure less than 1.4-inwc or more than 1.7-in. wc for natural gas. If manifold pressure isoutside this range, change main burner orifices.Fig. 47—Redundant Automatic Gas Control ValveA00158ON/OFFSWITCHINLETPRESSURETAPONOFFMANIFOLDPRESSURETAPLOW-FIREADJUSTMENTALLEN SCREW(UNDER CAP)HIGH-FIREADJUSTMENTALLEN SCREW(UNDER CAP)28