The heat-exchanger cools the air that is being forced through it by the furnace blower. As the warm air comes in contact with this cool surface the water in the air condenses. By pulling the water molecules from the air. According to the psychometric chart as relative humidity decreases in order to feel cool you will have to lower the temperature even more. A common way to counteract this effect is by installing a whole-home humidifier. Similarly, installing a high efficient system this need to turn the temperature down wont have such and influence on your energy costs.
In the refrigeration cycle, heat is transported from a colder location to a hotter area. As heat would naturally flow in the opposite direction, work is required to achieve this. A refrigerator is an example of such a system, as it transports the heat out of the interior and into its environment. The refrigerant is used as the medium which absorbs and removes heat from the space to be cooled and subsequently ejects that heat elsewhere.
Beware these aluminum clad wood doors. The wood is particle board. Why would anyone make a storm door out of particle board? They don't seal it in any way, it gets wet between the aluminum cladding and boils and blisters the aluminum and looks terrible in just a few years. I have two Larson's and they were horrible doors almost from the start. I've seen reviews and EMCO is the exact same way. When your storm door needs a storm door, you bought the wrong door.