Question: I just moved into a 900 sq ft 40's house... leaky, single pane, CHILLY etc. So I've just started insert shopping. How important will the ability to burn outside air be for me? Will burning internal air suck too much cold air through the house? Or will radiant heat tend to negate that issue? Answer: Outside air should not be important in such a house...unless you bought an open fireplace which uses an incredible amount of air.