I was checking air flows in a commercial building the other day. The building owner had received complaints of stuffiness, and HVAC systems not providing enough cooling to some zones. I came across a diffuser in a corridor that had no airflow. The balancing damper was wide open and all the other diffusers on the system were delivering cool air into adjacent offices.
A bit of checking revealed the root of the problem – a broken fusible link had allowed a fire damper to close. You can see half of the broken fusible link at the top of the photo.
I replaced the broken one with a new one.
In these circumstances it’s important to replace a broken fusible link with one that’s the proper size and rated at the correct temperature (usually 165°F). Luckily there was good access into the duct to replace the fusible link. The photo is taken inside a 6″ Ø duct, although it might seem bigger.
