When installing a gas appliance, what is the maximum permissible vent pipe length for proper draft, according to standards?

The maximum permissible vent pipe length for proper draft, as specified in installation guidelines, is 20 feet. This standard is in place to ensure that the venting system can effectively transport combustion gases outside while allowing enough draft to circulate air through the appliance. If the vent pipe length exceeds the recommended maximum, it may lead to inadequate draft, which can cause improper combustion or backdrafting of gases into the living space.

Staying within this limit is crucial for safety and efficiency, as longer vent pipes can create additional resistance, reducing the system's ability to expel exhaust safely. Therefore, while options such as 10, 15, and 25 feet may seem plausible, they either fall short of the optimal length or exceed the maximum capacity, compromising the appliance's performance and safety standards.