As these surround the fire, they are able to protect it from losing heat, and instead they suck warm air in from the room, and then blow it back out into the room when it has been heated further by the fireplace (of course it is filtered to prevent fumes). This way wood burning fireplace inserts help to make the room warmer more quickly and efficiently so that there is less heat lost. This in turn saves you money for firewood or work to collect it and it furthermore keeps your property warmer.

If you decide to use wood burning fireplace inserts this will greatly improve the heat output of your fireplace. However you must also bear in mind that this puts a heavy strain on the chimneys themselves as they are forced to deal with hotter air. Not all chimneys are designed to cope with this level of heat and so if you do purchase wood burning fireplace inserts it can be advisable to also improve the quality of your chimney flues and invest in extra insulation to protect them.