We have a see thru , gas logs fireplace. When lit, do we have to keep both sets of doors open , or can you close the one side your not sitting in. One side faces the family room, the other is the dining room! The sales person at the store we bought it from said to keep them both open or the closed doors would get to hot and could shatter! But the guy who came out to "set it up", said we could close one side! Who to trust!! Thanks for any answer!!