In a residential gas appliance vent system, which connector position is preferred when multiple connectors are used?

In a residential gas appliance vent system, the preferred choice when multiple connectors are used is the smallest connector. This is because using the smallest connector helps to minimize the potential for negative pressure which can lead to venting issues. Smaller connectors can facilitate a more uniform and efficient flow of gases, reducing the likelihood of backdrafts and improving overall venting effectiveness.

In contrast, larger connectors could lead to a decrease in velocity, which may allow harmful gases to accumulate instead of being expelled safely. The choice of connector size is crucial in ensuring safe and efficient operation of gas appliances, thus making the smallest connector the optimal choice in a system with multiple connectors.