My questions are:
1. Should I seal up the inner duct where it meets the upper duct - with what? heat resistant metal tape? I bought this metal plumbing repair tape at Lowe's and am uncertain what it's heat temp specs are or if it is for HVAC -- it lists none, Shurgard is the brand. Should I get another one that is rated instead, any recommendations? The other tape metal they had said for fiberglass.
2. Should I add the outer duct (8 inch) around the exhaust pipe, remove the old duct tape from the upper duct, and use metal tape to seal it? If so, do I need to screw in the bottom of the outer duct to the furnace?
3. Can I put any additional insulation around the ceiling (it's hot)? (The duct tape holding up a secondary piece of drywall with a flat sheet metal piece around the duct screwed in -- is falling down.) I assume I'll take off the old duct tape, stuff insulation in there if there isn't any, and use an adhesive to bind the drywall to the existing drywall as the screws have come out of the top drywall. Then seal up with the metal tape. I also have 1.5" styrofoam board if this can be useful.
4. Can I insulate around the outer duct as this will be hot from the outside air? If so, material?
5. What is the best way to manage the airflow and filtration into the unit? Should I weatherstrip around the opening on the side of the cabinet? Should I do something so that the air drawn in from the top of the furnace comes more directly from the hallway air instead of above the cabinet air? Are the duct-taped filters in the grill a good choice?
6. I found condensation on the line into the evaporator as well as a couple of large holes where cold air was blowing out around the pipes. I put a rubber pipe cover around it and stuffed the end into the sheet metal to block the airflow out. Is that okay?
Thanks for you help. I'm a newby at this but excited to learn how to do these things correctly, lowering the energy bills for my dad & helping the environment.
