Hansen's disease, also known as leprosy, is a chronic bacterial disease that primarily affects the skin, peripheral nerves and upper airway.ansen's disease, also known as leprosy, is a chronic bacterial disease that primarily affects the skin, peripheral nerves and upper airway.
1 Direct-vent gas fireplaces cost $1,000 to $3,500, plus $500 to $1,000 for installation. 2  The cost of a ventless gas fireplace is $500 to $2,500, and while there are additional installation costs, you may pay extra for finish work (such as a mantle, marble surround, etc.). The cost of a ventless gas fireplace is $500 to $2,500, and while there are additional installation costs, you may pay extra for finish work (such as a mantle, marble surround, etc.).
1 Options include fans to move the heat, remote controls, wall switches and wall -mounted thermostats. Inserts cost $1,200-$2,900, with professional installation adding another $600-$1,000.  A direct-vent gas fireplace doesn't need a chimney and is a way to add a fireplace where there isn't one.