We are building a new house. Since the house is almost 4000 sq ft, we have to have 2 furnaces and 2 air conditioners. The builder set the second furnace on the second floor. They have not hooked up the air conditioner yet. They set the furnace on a tray and have not hooked up the pipe from the furnce to the drain. Yesterday we saw about 1/2 inch of water in the tray. Does anyone know why? Thanks