Water Damage and Attic Installed Air Handlers

Most people are aware that air conditioning units can come as a package, everything in one box; or as a combination of two pieces of equipment, an outdoor condensing unit and an indoor air handler.  Remote, or split systems as they are often called, are specifically designed so that the air handling unit has to be located in an interior area where it can be safely operated and maintained.  One of the areas commonly used for air handler installation is the attic space of a building or residential structure.  Regardless of the location, provision must be made during the installation to catch water should the unit begin to leak.  It should be noted that water is a product of the cooling process.  That is, as air passes over the cooling coil, water can condense out of the air.  A drain line is typically connected to the cooling coil housing and routed away from the unit to the outside.  But, if for some reason the water does not drain correctly, it can begin to accumulate inside the air handler and will find a way to escape.  In order to capture the leakage and prevent structural damage, drain pans are commonly placed beneath the unit for this purpose.  It is the responsibility of the installing contractor to make sure that the drain pan is sufficiently large to catch whatever water leakage might occur wherever it happens to flow out of the equipment.  The photograph below shows a typical installation.  The problem that occurred here was that the drain pipe filled with debris and caused the drain water to back-up into the cooling coil and plenum.  When the water exited the unit, it missed the drain pan entirely and damaged the ceilings over the dining room and garage.  In this case, the drain pan was not large enough to fit under the air handler and plenum and was therefore useless.  Because of the damage that occurred, the installing contractor was held responsible.