A. Because you don't have a ducted heating system, a complete air conditioning system will have to be installed. This will consist of an air handler with a cooling coil, an outside condenser, refrigerant lines connecting the two and of course, the ductwork. If the contractor is a professional, he will perform a heat gain calculation to determine what size the system will be and how much cooling to deliver to each room. Once he has this information he will decide how to install the system.

During the summer, the temperatures in most attics are extreme; not a good location for a cooling system. In fact, having your air conditioning system installed in your attic may cost an extra 20% in electricity, not too mention the heat that will escape into the attic during the winter. Water is a byproduct of the cooling process and should the drain system fail, it is better to have it fail in a celllar than an attic. Also, air filters are an important part of a ducted cooling system and the required maintenance is much more likely to occur if the filter is easily accessible.

Air conditioning works fine when blown up out of floor registers, blowing downwards is not that important. Go with the cellar installation. You may lose some storage sapce but save a bunch of money in the long run.