At ~5:08 PM, Westmoreland 911 dispatched Station 20 (Murrysville VFC) for an Automatic Fire Alarm (AFA) at the Murrysville Get-Go on William Penn Highway. Station 20 responded with Truck 20 (3 firefighters), Squad 20 (3 firefighters), with 1 firefighter going directly to the scene, and 3 additional firefighters on standby at the station. Westmoreland 911 also dispatched the following additional stations to support Station 20: Station 22 (Export VFC), Station 64 (White Valley VFC), Station 78 (Sardis VFC), Station 30 (Delmont VFC), Station 87 Harrison City VFC), and Station 610 (Murrysville Medic One). Engine 22 was first on scene, with Chief 22 establishing the command, and finding no smoke or fire coming from the structure. Command 22 held the call to Stations 22, 20, and 64; returning all additional responding stations. Upon investigation of the structure's AFA and Roof HVAC Systems it was found that a faulty HVAC Duct Detector had activated the Structure's AFA System. The system was reset, the structure returned to the keyholder, and Command 22 returned all on-scene units. Truck 20 and Squad 20 returned to service and station.