Ventless fireplaces are known to be very convenient because they do not have to have a chimney of any kind and can be placed in almost any room in your house. You need to check with your own state codes on where they can be placed because some states restrict them from use in any bedroom area. This has to do with the potentially deadly fumes these types of fireplace can produce and spill over into a room. For those that have no other choice, ventless fireplaces are an alternative. However, they are seldom the best choice in many situations.
Ventless fireplaces use gel-fuel, bio-ethanol propane or other natural gases which produces no or very little odor. The fireplaces are considered ventless because the fuels used produce almost no smoke or fumes. The problem is the little they do produce can end filling your home and it may lead to carbon monoxide poisoning. This is one reson that if you chose a ventless fireplace you must accompany it with a carbon monoxide detector. This also makes choosing a ventless fireplace a choice that is done with care. If you have an area that needs to be heated but also has some cross ventilation should fumes be expelled into the room, a ventless appliance might work. Just be extremely careful where these fireplaces are placed.
Although they are around 99.9% energy combustion efficient, they can sometimes fill a room with carbon dioxide and vapor. This is because oxygen is a requirement when the gas is being burnt and water and carbon dioxide are produced as waste products of combustion. The oxygen in the room is continually consumed as more carbon dioxide is produced. If this happens for long periods, your room may end being lifeless since all the oxygen has been exhausted. This may cause suffocation. To avoid this, try as much as possible to use a ventless fireplace as a supplement source of heat not the main source. If you own one of these fireplaces you can use a dehumidifier to remove the excess water vapor in the room. This will also cut down on the possibility of mold that may develop from the water vapor that is produced. The bottom line is to take the right precautions when using a ventless fireplace.