On horizontal applications installed in the attics of houses, there exists a primary pan underneath the coil encased in the housing and then a secondary pan is installed directly beneath the unit if in the event the primary fails. This secondary pan is a joke. First of all it is flat bottomed but installed on a slant and second of along it does not allow for condensate to easily flow out the pvc. Rather it builds up in the pan and then rusts it. I have since started using a new product that is made of ABS(plastic) and has a sloped bottom side centerdrain that is much better. In fact all you do is connect an elbow and the 3/4 in. pvc to it and its done. Cheaper than the metal flat bottom pans. Has any other person out there wondered why we even still have flat bottomed sheet metal pans installed on these type of systems?