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

A furnace type associated with a flue gas temperature range of 280 F - 300 F is Category I. This type of furnace is typically used for natural draft or atmospheric venting systems and uses conventional vertical venting. Category II, III, and IV furnaces are not associated with this temperature range. Category II furnaces have a higher flue gas temperature range, between 300 F - 450 F, and use a mechanical draft system. Category III and IV furnaces utilize a condensing technology and have a lower flue gas temperature range of less than 200 F. These types of furnaces are not associated with the given temperature range.