This is my house but it has bugged me since moving in 4 yrs ago. My home has two heating/AC systems, one in the basement and the other in the attic. Both are forced air gas fired systems. The unit that serves the second floor blows cold air for about 4-5 seconds in the Winter each time it runs. I understand that the ducting is located in the unheated attic and it makes complete sense that I would get a short blast of cold air whenever it first comes on but it just seems like a design problem. This is my first home with a heating plant located in the attic. Is this a common complaint?