06-09-2011, 08:53 AM
Both of my AC units are in my attic so I want to make sure the secondary drain is working properly. I just had one unit replaced. The primary drain is working and piped to the house sewer system. The secondary drain on the collector pan is capped, but there is a large pan under the entire evaporator which would capture any water dripping out of the bottom of the evaporator. If the collector pan overflows, then the condensate would just have to find its way out however it could. My other unit has the secondary drain hole open so that if the level in the internal pan gets above the primary drain, then it will flow out the secondary drain into the overflow pan and out to the telltale pipe. However, because the hole is open, some cold air is always flowing out that hole and into the attic. My question is, can the secondary drain be connected in such a way that it will it will work reliably, but without the air leakage? What's the best practice for the secondary drain?