In this video my HVAC contractor Gilbert Rosipal from AirRite shows us the inner workings of a 95% efficient gas furnace. You'll see the concentric pipe used for the sealed combustion chamber and the pvc vent pipe through the roof. We'll also discuss why we like to hang our units from the rafters rather than sitting them on the attic floor. -Matt Risinger Principle of an Austin Texas based High Performance Builder and Remodeling Company www.risingerhomes.com