My home was recently inspected for sale. Inspector said "The condensate line does not have a "P" trap.
1. What is a "P" trap and where does it go?
2. Is it necessary for proper function of the condensate drain line?
Thanks//JoeDP39@cs.com

 

The trap he is talking about would go into the drain from the air conditioner coil above the furnace. If it is and it sounds like it might be piped straight into the houses' drain pipe or vent. What can happen is sewer gases can get into the furnace plenum. To stop this a P Trap which looks like a pipe with a u shaped bend can trap water in it stopping the sewer gas from getting back to the furnace.
On an air handler were the blower is after the coil the negitive pressure keeps the coil from draining. By adding a Trap that goes 3 -4 inches down then back up. Gravity can help the water drain against the negitve presures.
Good Luck
Mr Foster