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Inside an apartment, there a horizontal fan-coil unit, such as a First Co. 26HX, with enclosure, mounted in a soffit below the rated ceiling. There is a primary condensate drain line that attaches to the pan, and terminates in the lavatory drain tailpiece just upstream from the lavatory P-trap, similar to this: https://www.jrsmith.com/uploads/fileLibrary/d9200.pdf
In lieu of a secondary overflow drain, there is an overflow shutoff switch.
Q1: Since the lavatory drain tailpiece has its own P-trap below it, is there any need for another trap+vent for the primary condensate line, up near the fan-coil unit in the soffit?
Q2: If the answer to #1 is "yes", can this additional trap occur inside the enclosure if it is made of PVC? (Thinking of flame spread, smoke etc. of combustible materials in plenums.)
Q3: If the answer to #2 is "yes", is an air gap or vent required, or is the condensate drain pan itself a type of air gap, even in the presence of negative pressure in the HVAC enclosure?
In lieu of a secondary overflow drain, there is an overflow shutoff switch.
Q1: Since the lavatory drain tailpiece has its own P-trap below it, is there any need for another trap+vent for the primary condensate line, up near the fan-coil unit in the soffit?
Q2: If the answer to #1 is "yes", can this additional trap occur inside the enclosure if it is made of PVC? (Thinking of flame spread, smoke etc. of combustible materials in plenums.)
Q3: If the answer to #2 is "yes", is an air gap or vent required, or is the condensate drain pan itself a type of air gap, even in the presence of negative pressure in the HVAC enclosure?
