Hi All - Newbie here. I've researched this question (here and elsewhere) and I can't find an answer, so I'm hopeful I can get some help. I have two identical units - one on the main floor vented immediately to the outside (~2-3 feet) and one in the basement which requires ~30 feet of venting to the outdoors with a couple of 90 degree bends. The main floor unit works beautifully; the basement unit won't stay lit as the weather gets colder (I live in MA so it can get 'wicked cold'). Given the two are identical in all other ways, I'm assuming the difference in venting length is the reason. (...duh). Is there anything I can do to fix this, other than move, that is? Is there another explanation I'm not considering? Thanks.