depending on the house and existing ducts its usually pretty easy. first you must make sure you have enough wires between your thermostat and the furnace, a Y is what you need, may need to run new wire but maybe not. next a section of duct needs to be cut out above the furnace then the evap coil will be installed in that spot and sealed into the ducts. next we place the condenser somewhere around the house this is pretty simple most of the time. then comes the hard part. we need the run the line set (two copper tubes plus a two wire) from the evap coil to the condenser, if you have a crawlspace, unfinished basement, or a drop ceiling this goes very quickly and easily. the last part is to have the electrical ran from your breaker box the the outside of your house at the condenser then the electric is hooked up to the unit. depending on your local codes you can use the same hole the lineset comes through. then once the lineset is sweated in at both ends a vacuum is pulled on the system and checked for leaks. then the system is charged with the refrigerant (either shipped in the condenser or must be filled from tanks). its not too hard but it is law to have a EPA certification to handle refrigerant or charge the system. if you DIY this call out a pro to do the charging of the system