Carrier 59SC5B Installation, Start-up, Operating And Service And Maintenance Instructions

Also see for 59SC5B: Product data

45Recommended Combustion Air Inlet Moisture TrapRecommended to prevent moisture from trickling into the furnacevestibule, a trap can be installed in the intake air pipe near thefurnace. To prevent moisture, connecting a drain line to the trap isrecommended as trace amounts of moisture will evaporate into theintake air stream. If the combustion air inlet is located near amoisture exhaust duct, or there are other concerns of excessivemoisture being drawn into the combustion air inlet, it isencouraged to connect a drain line to the trap.The trap can be constructed from a running tee of the samediameter of the intake air pipe with EITHER a removable capattached to a 6-inch long pipe connected to the tee or the ExternalVent Trap Kit to help prevent contaminants from entering thefurnace. See Fig. 40.The External Vent Trap Kit accessory may be used as a trap for thecombustion air inlet pipe if a large amount of moisture must beremoved. The drain line may be connected to the same drain as thefurnace condensate and the evaporator coil condensate line ONLYif the inlet air trap drain and the evaporator coil drain empty into anopen segment of pipe above the drain. See Fig.17. When usingthe External Vent Trap Kit, refer to those instructions for properdrain connections.The tee may also be connected to the intake air pipe on the side ofthe casing. See Fig. 40.In any configuration, it will be necessary to add the equivalentlength of the tee (15 feet/5 M) to the Total Equivalent Vent Lengthof the venting system.ADDITIONAL INFORMATION FORPOLYPROPYLENE VENTING SYSTEMSPolypropylene venting systems include flexible vent pipe.These flexible vent pipes have a different equivalent ventlength than straight sections of PVC/ABS DWV vent pipe. Besure to make the appropriate deductions from the MaximumEquivalent Vent Length (MEVL), or additions to the TotalEquivalent Vent Length (TEVL), when applying flexible ventpipes in polypropylene venting systems. See thepolypropylene vent system manufacturer’s installationinstructions for details.When using metric-sized venting systems, use theseequivalencies for obtaining the proper MEVL from the Tables:Use 2” Vent Tables for 60 mm (o.d.) vent systemsUse 3” Vent Tables for 80 mm (o.d.) vent systemsUse 4” Vent Tables for 100 mm (o.d.) vent systemsNOTICEThe measured length of pipe used in a single or 2--pipe terminationis included in the total vent length. Include deductions from theMaximum Equivalent Vent Length (MEVL) contained in theVenting Tables for elbows and flexible vent pipe. Factoryaccessory concentric vent terminations or pipe lengths and elbowsused for “standard” vent terminations do not require a deductionfrom the Maximum Equivalent Vent Length. See vent terminationfigures associated with Table 16. Include a deduction for a Teewhen used for Alberta and Saskatchewan terminations.NOTE: Polypropylene venting systems MAY require additionaldeductions from the MEVL, or additions to the TEVL, for ventterminations and flexible pipe sections. See the polypropyleneventing system manufacturer’s instructions for details onequivalent lengths of vent terminations and flexible vent pipes,and for calculating total vent lengths.To calculate the Total Equivalent Vent Length (TEVL) of theventing system:1. Measure the individual distance from the furnace to the ter-mination for each pipe.2. Count the number of elbows for each pipe.3. For each pipe, multiply the number of elbows by the equi-valent length for the type of elbow used. Record the equi-valent length of all the elbows for each pipe.4. If a Tee is used on the termination (Alberta and Saskat-chewan, when required) record the equivalent length of theTee used.5. Calculate Total Equivalent Vent Length by adding the equi-valent lengths of the fittings to the lengths of the individualvent and combustion air pipes.6. When using polypropylene venting systems with flexiblevent pipes, perform adjustments for the equivalent length ofthe flexible vent pipe to the calculated total equivalentventing system length. See the polypropylene vent systemmanufacturer’s instructions for details.7. Select a diameter of vent pipe from Tables 16 and note theMaximum Equivalent Vent Length (MEVL) shown for thatapplication for that specific furnace input size. Compare theTotal Equivalent Vent Length (TEVL) to the MEVL:8. If the Total Equivalent Vent Length is shorter than theMaximum Equivalent Vent Length for the diameter of pipechosen, then that diameter of pipe selected may be used.9. If the Total Vent Length is longer than the MaximumEquivalent Vent Length for the diameter of pipe chosen,that diameter pipe MAY NOT be used for venting thefurnace. Try the next larger diameter pipe.NOTE: If the calculated Total Equivalent Vent Lengths results indifferent diameter pipes for the vent and combustion air, select thelarger diameter for both pipes.NOTE: If the Maximum Vent Length for diameter of the pipeselected is longer than the measured length and the equivalentlength of all the fittings and terminations (TEVL), recalculateTotal Equivalent Vent Length using the next smaller diameter. Ifthe Maximum Equivalent Vent Length is still longer than thelonger TEVL of the vent pipe or combustion air pipe, then thatdiameter of pipe selected may be used.When installing vent systems pipe lengths of 10 ft. (3 M) or less,use the smallest allowable pipe diameter. Using a pipe size greaterthan required for short venting systems may result in loss ofefficiency, incomplete combustion, flame disturbance, or flamesense lockout.For vent systems longer than 10 ft. (3 M), any larger diameter ventpipe shown in Table 16 FOR THAT SIZE FURNACE may beused.Combustion Air and Vent Piping InsulationGuidelinesNOTE: Use closed cell, neoprene insulation or equivalent.The vent pipe may pass through unconditioned areas. The amountof exposed pipe allowed is shown in Table 15.1. Using winter design temperature (used in load calculations),find appropriate temperature for your application and fur-nace model.2. Determine the amount of total and exposed vent pipe.3. Determine required insulation thickness for exposed pipelength(s).4. When combustion air inlet piping is installed above a sus-pended ceiling, the pipe MUST be insulated with moistureresistant insulation such as Armaflex or other equivalenttype of insulation.5. Insulate combustion air inlet piping when run in warm, hu-mid spaces.