Residential HVAC Installation Practice Exam 2026 - Free HVAC Practice Questions and Study Guide

Friction in ductwork will always exist to some extent, regardless of the material used, due to the resistance of the air flowing through the ducts and the roughness of the duct walls. While certain duct materials may minimize friction to a certain degree, it cannot be completely eliminated. Therefore, option B is the most accurate choice. Option A is incorrect as it is not possible for friction to be completely eliminated. Option C is incorrect as the degree of friction reduction may vary depending on the material, but complete elimination is not possible. Option D is incorrect as the information provided in the question is sufficient to answer it.