HVACR NewsMagazine

5/12 pitch roof make it a challenge at best and impossible in some cases. It isn’t that it can’t be done but it can’t be done at an affordable cost to the consumer. In fact, I would suggest that the tight places might require closed cell foam and that is expensive, difficult, messy, and can result in significant loss of insulation material as well. 2a. After Wrap is Applied Benefits : Inspecting the duct after the insulation is installed is much better for the installer but tough for the inspector. At this stage of the process, inspectors may choose to slit the wrap so they can look inside to see if the mastic or tape is installed correctly. 2b. Drawbacks : The question is, “How many places should they check?” I have heard two or three and as many as a dozen. Some inspectors use a higher number until they are familiar with the dealer/installer then they reduce the number if the installer has proven themselves to be credible. Either way, the big question is, “Who is responsible for resealing the duct wrap?” Almost without exception, inspectors will leave that to the installing dealer. The next question is, “How is the installer to know where the wrap was slit?” Does the installer have to be present for the inspection? I have not yet heard of a systematic approach with some sort of marker that cannot be missed. If a slit is missed and the result is condensation and damage to the

Checking New Construction

Duct Tightness/Leakage

No matter how hard we try, everyone makes a mistake from time to time. That is why code inspectors are our friends. They help us find those peccadillos before they turn into a repair claim—simply because we made one of those little or not so little mistakes. Checking for leaks in ductwork are not so easy and that is why we find ourselves in a quandary at times. There are at least three ways to check for leaks: 1. Visual check at rough in before the duct wrap is applied 2. Visual check at rough in after the Each of these has its benefits and its drawbacks and we’ll try to cover each. 1a. Before Wrap is Applied Benefits : If the duct is completely exposed, the inspector can easily see the mastic or mastic tape used by the installer. Does the tape carry the required UL listing? The inspector can see if the mastic or tape was properly applied to the transverse joints and longitudinal seams per code. 1b. Drawbacks : It is almost impossible to wrap a duct system after it has been installed / hung. The straps, the tight places in every house but especially in a 4/12 or duct wrap is applied 3. Duct blaster test