A water heater venting code is a set of safety standards used to ensure proper installation and ventilation of a water heating unit. Check with your state before installing a water heater as safety codes may vary by location.
The main danger of an improperly vented water heater is carbon monoxide omission. Compliance with state venting codes ensures proper water heater ventilation, displacing and removing all carbon monoxide from the home.
Aspects of proper ventilation include the use of correct venting material as well as maintaining a set distance from combustible materials. Most ventilation codes specify a list of approved locations for installing a water heating unit.