Today, I replaced the exhaust fan in my laundry room. I didn't realize that there is an insulated HVAC duct right next to the exhaust fan in the ceiling. As I was wrestling the old fan out, I tore a 3 inch long slit in the duct. It did tear all the way through, and I can poke my finger into the inside of the duct.
Note the the duct I tore is for the heating and air conditioning system. My exhaust fan duct was not harmed. Also, the location of the duct is in the ceiling between the first floor and the second floor (it is not in an attic).
As a temporary fix, I put some Nashua foil tape over the slit in the duct. I turned the furnace on and used my hand to verify that no air is escaping from the slit. Though, with the furnace on, the foil tape was slightly warmer than the rest of the duct. (No surprise – the foil tape is a much worse insulator than an insulated duct.)
Anyway, my question is: if I don't want my duct to leak, is it important that I do a more elaborate fix? Is the foil tape likely to come off on its own?
The more elaborate fix I am thinking about doing is to buy some insulated ducting material, put it over the foil tape that I already put on the duct, and then wrap more tape all the way around the circumference of the duct.
P.S. This is approximately the type of insulated ducting in my ceiling:
Best Answer
Get a flex duct connector like is used to join two sections of flex together.
Cut completely through at the tear.
Fit the union into the inner sleeve.
Tape inner sleeve to connector.
Pull insulation back over the joint and tape well with duct tape.
If you want to insure it not pulling apart screw through duct tape with sheet metal screws around both sides into the connector. Another method very similar uses big zip ties to secure the insulation and vapor barrier. And screws and tape to secure inner sleeve to connector
This video shows it very well.