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

Also see for 58MEB: Owner's manual

-- 55 --In Canada, the input ratings must be derated by 5 percent foraltitudes between 2001 ft to 4500 ft (1524.3 to 1371.6 M) abovesea level.Furnace input rate must be within ± 2 percent of input on furnacerating plate adjusted for altitude.1. Determine natural gas orifice size and manifold pressurefor correct input.a. Obtain average gas heat value (at installed altitude)from local gas supplier.b. Obtain average gas specific gravity from localgas supplier.c. Verify furnace model and size. Table 13 can only beused for model 58MEB furnaces with rating plateheating inputs (1000’s Btuh) of 040 through 120.d. Find installation altitude in Table 13.NOTE: For Canadian altitudes of 2001 to 4500 ft (609.9 to1371.6 M), use U.S.A. altitudes of 2001 to 3000 ft (609.9 to914.4 M) in Table 13.e. Find closest natural gas heat value and specific gravityin Table 13 or 14.f. Follow heat value and specific gravity lines to point ofintersection to find orifice size and manifold pressuresettings for proper operation.EXAMPLE:(0-2000 ft (0 -- 609.9 M) altitude using Table 13)Heating value = 1050 Btu/cu ftSpecific gravity = 0.62Therefore: Orifice No. 45 andManifold pressure 3.6-in. wc* Furnace is shipped with No. 45 orifices. In thisexample all main burner orifices are the correct sizeand do not need to be changed to obtain the properinput rate.Check and verify burner orifice size in furnace. NEVERASSUME ORIFICE SIZE; ALWAYS CHECK AND VERIFY.2. Adjust manifold pressure to obtain input rate.NOTE: Manifold pressure must always be measured with burnerenclosure front REMOVED. Gas meter must always be clockedwith burner enclosure front INSTALLED.a. Remove burner enclosure front.b. Remove seal cap that conceals adjustment screw forgas valve regulator. (See Fig. 55.)c. Jumper R and W thermostat connections on control tostart furnace.d. Turn adjusting screw, counterclockwise (out) todecrease manifold pressure or clockwise (in) toincrease manifold pressure.NOTE: This furnace has been approved for a manifold pressureof 3.2 in. wc to 3.8 in. wc when installed at altitudes up to 2000 ft(609.6 M). For altitudes above 2000 ft (609.6 M), the manifoldpressure can be adjusted from 2.0 in. wc to 3.8 in. wc. If manifoldpressure is outside this range, change burner orifices to obtainpressure in this range.UNIT DAMAGE HAZARDFailure to follow this caution may result in reducedfurnace life.DO NOT bottom-out gas valve regulator adjusting screw. Thiscan result in unregulated manifold pressure and result inexcess overfire and heat exchanger failures.CAUTION!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.½ “ NPT Inlet½” NPT Outlet1/8” NPT ManifoldPressure Tap1/8 NPT InletPressure TapRegulator Seal CapRegulator AdjustmentUnder CapON/OFF SwitchA07536Fig. 55 -- Redundant Automatic Gas Control ValveBURNERORIFICEA93059Fig. 56 -- Orifice HolesUNIT DAMAGE HAZARDFailure to follow this caution may result in componentdamage.DO NOT redrill orifices. Improper drilling (burrs, out-ofround holes, etc.) can cause excessive burner noise andmisdirection of burner flames. (See Fig. 56.)CAUTION!