A Bellows is a device which can be used to increase the air flow through another device which lets them burn at a hotter temperature. However, by burning at a hotter temperature they will also consume fuel faster. The bellows can provide air to a device that is directly in front of it, or in front and one block down. This allows it to provide air to a Firepit, or a Charcoal Forge for example.
Recipe: tfc:crafting/bellows
To use the bellows, simply place it facing the targeted heating device, and use it. The bellows will pump air into the device, raising the maximum temperature for a short time.