1.   Another duct is installed to expel the combustion gases.

2.   A more effective solution involves installing a duct that supplies fresh air from outside directly to the furnace.

3.   Make sure the heating and air ducts are properly installed.

4.   Or if you purchase a clothes dryer, you will have to install a duct to carry the hot air through an exterior wall.

5.   While Ms. Clark has returned to work, installing heating ducts in new office buildings and factories, she continues her fight against GHB in the evenings.

6.   An exhaust duct was installed to draw out dust and fumes from power machinery.

7.   An exhaust duct was installed to draw out dust and exhaust from power machinery to clean the air inside the tunnel.