Question

a trap in the condensate line of a split - system air conditioner
is more important on pans upstream of the house air fan
is not required if the condensate drains into a waste plumbing stack
prevents heated air in the winter from being blown outside through the condensate drain line
is the same size as a plumbing trap
will not work if the condensate drain line is under negative pressure
question 9

Explanation:

A trap in the condensate line of a split - system air conditioner prevents heated air in the winter from being blown outside through the condensate drain line. This is because it creates a barrier to stop air flow while allowing condensate to drain. The other options are incorrect as the importance of the trap is not related to the position relative to the house air fan upstream, it is still required even if the condensate drains into a waste plumbing stack, it is not necessarily the same size as a plumbing trap, and it can work under negative pressure to some extent as long as the trap seal is maintained.

Answer:

prevents heated air in the winter from being blown outside through the condensate drain line