One of the most important factors that you will need to consider before purchasing one of these ventless gas inserts is your home's overall structure. This means evaluating where your home is located and how much space you actually have. For instance, if you have a very small fireplace, it may not make sense to invest in a ventless gas insert. On the other hand, if you have a large open fireplace idn poker, you may find that a ventless gas fireplace insert would be the perfect solution for your home.