Performed 1 system heating maintenance. System is pulling in attic air from both plenums and needs to be sealed with tape and mastic to keep outside air from mixing. ducting boots have gaps and are using the insulation as a filter, signified by black insulation. Boot to drywall seal with expanding foam needed to separate attic from living area. Ducting very dirty inside and needs to be professional cleaned with duct cleaning machine. No surge protection on system leaving it open to electrical component damage. Recommend installing surge protector that will keep system safe as well as warranty parts.