An addendum to my earlier response about using just hot tap water:
We used to have several house cats for a number of years (in OH) and found that we would get some amount of cat hair (from shedding) in the condensation drain pipe. If I didn't run hot water down the drain pipe on a fairly consistent/regular basis, it would clog due to the cat hair. Didn't have the best/tightest air filtration at our previous house and the air handler had a fairly small diameter drain pipe.......so there were several contributing factors to the clogging.
Moral: If you have pets that shed, you might have to do the drain cleaning on a more frequent basis.
Bill
