Arkansas HVACR NewsMagazine January 2019

S tate, National, Chapter News Tech News

HEAT EXCHANGER CRACK DIAGNOSIS Article Furnished by Bryan Orr, There are two camps I’ve run into regarding cracked heat exchanger diagnosis. Those who look for it everywhere and those who dismiss it and never look. I will start by saying that everything I write here is my own opinion and experience. Because this is such a hot button topic don’t take my word for any of this, follow manufacturer, industry standards and codes and obviously stop reading unless you are a trained and licensed professional. Heat exchanger cracks are worth finding but they aren’t the most dangerous issue for your customers in most cases The reason I make this blasphemous statement is twofold. 1. Many heat exchangers are at a negative pressure in reference to the air moving over the exchanger. This means that the air from the return will move into the exchanger rather than combustion gasses moving into the airstream. 2. So long as the combustion process is complete there won’t be significant CO ( Carbon Monoxide) in the flue; but, let’s be clear… If there are any cracks in an exchanger it needs to be replaced,

there should NOT be cracks in a heat exchanger. The trouble comes in when we think that looking for cracks in the only or even primary method of finding CO issues with a furnace. When we rely on our eyes to find every issue we can easily miss problems (including cracks) that our eyes can’t see. So here are my suggestions on how to find cracked heat exchangers and other furnace safety issues. Ambient Carbon Monoxide One of the first things you should do is measure ambient CO in the conditioned space while the heat is running with either a combustion analysis tool or a personal CO detection device. Anything other than ZERO ambient carbon monoxide is worth investigating. Sure, smoking indoors or cooking can increase