What is a potential issue with increased resistance to flow in a venting system?

Increased resistance to flow in a venting system primarily leads to poor venting performance. When there is high resistance, the ability of exhaust gases to escape efficiently is compromised. This inadequacy can result in incomplete combustion or backdrafting, where combustion gases can flow back into the living space instead of being vented outside. Poor venting performance can also lead to the accumulation of harmful gases such as carbon monoxide, posing safety risks.

The other options do not accurately describe the implications of increased resistance to flow. While enhancement of the combustion process and increased gas pressure may imply some benefits, they are not outcomes associated with high resistance in a venting system. Similarly, although some forms of resistance (like that seen in poorly designed or obstructed systems) could lead to reduced efficiency in heat transfer, the most direct consequence of increased flow resistance is indeed a decline in venting performance. This highlights the critical need for proper venting design and maintenance to ensure safe and efficient operation of combustion appliances.