Vented gas logs must be vented through a functional chimney in order to move all burning by-products outside the home. Vented gas logs produce the most realistic flames but put off less heat than their vent-free counterparts due mostly to the fact the chimney flue must be open when the fireplace is in use.

What happens if you don't vent a gas fireplace?

Without proper ventilation and safety systems in place there can be serious health risks associated with burning gas in a ventless fireplace. Ventless fireplaces produce small amounts of nitrous dioxide and carbon monoxide which can be deadly in large doses.

Are my gas logs vented or unvented?

Follow the gas line from beneath the logs to where it disappears in the wall or floor. If the gas is merely contained by a simple gas line, then the logs are vent free. If there is a small cylinder attached to the gas line, then the logs are vent-free.