For some background.. I live in an older, 1955 era house with two levels. We don't use the upstairs hardly ever, except for when I visit my man cave, aka the ham radio room. There is a door on the stairs, in the main living area where my stove is located. Today, I decided to leave the door open and let some heat get upstairs instead of running the space heater. Now, the weird part. It's comfy upstairs, and even warmer then normal downstairs, 73 on the thermo, which I usually can't get past 71. It feels nicer downstairs, and the heat seems to be more, even... The room that is usually ice cold when I'm not in it is directly above the stove room. Is it possible, that with it being warmer up there by letting the stove heat go upstairs, that I'm not losing heat through the floor above the stove? I might just be crazy, but it feels that way to me. When I first opened the upstairs door today there was a huge blast of cold air flooding into the lower level. Also, I'm young and don't claim to be very home smart. Is it a bad idea to leave the big room upstairs "it's huge" closed off and cold? Can I cause any eventual issues that way? I usually always close the door to the stairs, even when I go up there twice a week. Sometimes, it gets down to 50 degrees or colder up there. Thoughts?