Gas Heat ESCO Practice Exam 2026 - Free Gas Heat ESCO Practice Questions and Study Guide

When a standing pilot furnace ignites and the flames "roll out", this is typically due to poor combustion, causing the flames to come out of the furnace instead of being contained within it. This issue is often a result of improper burner operation or a blockage in the furnace, such as a clogged filter. A clogged filter can restrict proper airflow, leading to incomplete combustion and the flames rolling out. Therefore, the correct answer is A.

Options B, C, and D are not directly related to the issue of flames rolling out in a standing pilot furnace. A faulty vent may cause other issues such as improper ventilation, incorrect thermostat settings would not cause the flames to roll out, and low gas pressure could result in other combustion problems but not specifically flames rolling out.