I was Dispatched for water coming out from behind the thermostat. I found a Air Handler in the attic that had a clogged primary drain line. The water was coming out of the secondary. I added a drain line isolator and cleared the drain. The clog was difficult and very sluggish to clear. I would highly recommend a new primary drain line and a new secondary pan and line. I recommend both lines come out and run down the outside wall instead of into to plumbing. If the line clogs again the Customer will need a plumber. Unless we rerun everything outside. $1,285.00 to replace the secondary drain pan and re-do the drain connections at the Air Handler. $2,950.00 to replace the secondary drain pan and both drain lines. We will run the drains outside and eliminate the plumbing connection.