The venting system for gas heating equipment consists of the following:
1. The chimney or smoke elimination pipe.
2. The draft diverter or draft diverter hood.
Gas-burning equipment must be vented to the outside. All pipes leading from the equipment must be fitted so that the joints are tight and free of leaks.
A draft diverter or draft hood is a wind deflector placed in the chimney to prevent downdrafts of air (i.e., air moving down the chimney from the outside) from blowing out the pilot light. Many draft diverters are designed and positioned so that the downdraft is deflected into the room containing the heating unit.
Any room containing gas heating equipment must have adequate ventilation. Provision for incoming air (i.e., air necessary for combustion) is especially important in rooms or buildings of tight construction. The minimum area requirements (in relation to each 1000 Btu/h input) for both ventilating air openings and air inlet openings can be obtained from the manufacturers of the gas-fired appliance.