Power surges are the silent killer of appliances and HVAC equipment. Most homeowners protect their electronics, but don't protect more important equipment. A power surge can destroy equipment, and you won't know the cause. Now you do. The AG3000 surge protector (SPD) is easy to install and is a perfect option for HVAC equipment. A green LED illuminates when the SPD is working properly. A red LED illuminates when protection is diminished and the SPD needs to be replaced. The proven, state-of-the-art Thermally Protected Metal Oxide Varistor (TPMOV) technology eliminates potentially dangerous failure modes commonly associated with standard MOV technology. UL Listed to ANSI/UL 1449 5th Edition. Distribution panel HVAC equipment protection Service door