I have not piped my intake outside. If it is in your basement I would leave it drawing air in from there. I would not want cold air from outside coming into the boiler when it is really cold outside. I think it would be better for your 60ish air in the basement to be taken into the boiler. As far as a cold boiler goes. I have had an occasional "bridging effect" because of a larger split holding up the other wood and the coals burning right out from underneath it. You have to watch out for that as well.