This article was written by HVAC/furnace technician Benoît Mongeau. Thank you, Ben.     High efficiency (or 90%, or condensing) furnaces use a set of two heat exchangers to retrieve more heat from the combustion products than their mid-efficiency counterparts. Because of this, they generate flue gases much colder than those of a mid-efficiency or […]

My good friend and contributor to HVAC School, Neil Comparetto, made this video showing how he creates access ports for static pressure and gas combustion analysis. As techs, we find ourselves in the tough position of needing to drill access holes to take measurements, but the drilling and sealing of the holes can sometimes create […]

In order to wrap my head around diagnostic issues, it helps me engage in thought experiments where I think of more extreme examples of an issue or situation or consider the ideal to find the “edges” of a concept. Once I find the extreme edges, I can begin to sort down to a more exact […]