Tech replaced crushed start collar for return on Trane air handler. Secured new start collar with 3 screws and sealed with mastic tape. Reconnected 6” flex duct and secured with 2 panduits, mastic tape and FSK tape. There used to be a 12*20 filter inside old air handler. There is no filter slot in return box and no filter slot available inside new air handler. Returns in ceiling are fire dampers. AHU 2 needs a filter slot cut. Jerry says they take care of their own filters. Tech let staff on site know.