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

Also see for 58MTB: User's information manual Owner's manual Service and maintenance instructions

Attachment of Combustion Air Pipe1. Determine location of combustion air intake pipe connectionto combustion air intake housing as shown in Fig. 38 forapplication.2. Reposition combustion air intake housing plug fitting inappropriate unused intake housing connection.3. Install combustion-air pipe grommet (factory-supplied inloose parts bag) into selected furnace casing combustion-airpipe hole. (See Fig. 40.)4. Insert assembled combustion air inlet pipe into intake housingas shown in Fig. 38.5. Drill a 1/8-in. hole in 2-in, combustion air pipe using the holein intake housing as a guide.6. Install a field-supplied No. 6 or No. 8 sheet metal screw intocombustion air pipe.7. Install casing hole filler cap (factory-supplied in loose partsbag) in unused combustion air pipe casing hole.NOTE: Do not attach combustion air intake pipe permanently tocombustion air intake housing since it may be necessary to removepipe for service of burner box components or flame sensor.Attachment of Combustion Air Intake Housing Plug FittingThe combustion-air intake plug fitting must be installed in unusedcombustion air intake housing. This fitting must be attached byusing RTV sealant, or by drilling a 1/8-in. hole in fitting, usinghole in intake housing as a guide. Install a field-supplied No. 6 orNo. 8 sheet metal screw.NOTE: DO NOT OVERTIGHTEN SCREW. Breakage of intakehousing or fitting may cause air leakage to occur.A plugged drain connection has been provided on this fitting foruse when moisture is found in combustion air intake pipe andcombustion box. If use of this drain connection is desired, drill outfitting’s tap plug with 3/16-in. drill and connect a field-supplied3/8-in. tube. This tube should be routed to open condensate drainfor furnace and A/C (if used), and should be trapped, as shown inFig. 42.NOTE: (Direct Vent/2-Pipe System ONLY). Moisture in com-bustion air intake may be a result of improper termination. Ensurecombustion air pipe termination is similar to those as shown in Fig.44 so that it will not be susceptible to area where light snow orothers sources of moisture could be pulled in.VENT PIPEGeneralFurnace vent connection must be attached as shown in Fig. 38.CARBON MONOXIDE POISONING AND PROPERTYDAMAGE HAZARDFailure to follow this warning could result in propertydamage, personal injury, or death.Vent pipes must be airtight.NOTE: A 2-in. diameter pipe must be used within the furnacecasing. Make all pipe diameter transitions outside furnace casingper Fig. 41.The minimum vent pipe length for these furnaces is 5 ft. Short pipelengths (5-8 ft) may discharge condensate droplets. These conden-sate droplets may be undesirable. A 12-in. minimum offset pipesection is recommended to reduce excessive condensate dropletsfrom exiting vent pipe outlet. (See Fig. 43.)Attachment of Vent Pipe1. Determine vent pipe diameter and maximum pipe lengthsusing Table 12.Table 10—Maximum Allowabl Exposed Vent Pipe Length (ft) With and Without Insulation inWinter Design Temperature Ambient*UNITSIZEWINTER DESIGNTEMPERATURE(°F)MAX PIPEDIAMETER(IN.)WITHOUTINSULATIONWITH 3/8–IN. ORTHICKER INSULATION†06020 2 44 700 2 21 70-20 2 20 5708020 2 55 550 2 30 55-20 2 16 5520 2.5 58 700 2.5 29 70-20 2.5 14 6710020 2.5 40 400 2.5 38 40-20 2.5 21 4020 3 63 700 3 30 70-20 3 12 7012020 3 70 700 3 38 70-20 3 19 7020 4 65 700 4 26 70-20 4 5 65* Pipe length (ft) specified for maximum pipe lengths located in unconditioned spaces. Pipes located in unconditioned space cannot exceed total allowable pipe lengthas specified in Table 11.† Insulation thickness based on R value of 3.5 per in.34→