1. Gas Appliance Vents
The purpose of your gas appliance vents is to convey the combustion by-products to the exterior of the home. Leakage of combustion by-products such as carbon monoxide can cause illness or even death. Depending on duct tape to ensure these gasses make it to the outside is dangerous. It fails, and most times is installed poorly anyway. If you have a separation in your gas appliance vent, call an HVAC contractor to repair it correctly.
2. Plumbing Pipes
Despite viral videos of duct tape boat repairs, duct tape doesn’t do well with water. The water will eventually make its way out and if its the crawlspace, it could be a long time before you notice the leak. Mean while its rotting your wood, attracting termites, and mold is growing. A whole role of duct tape isn’t going to save you. Just call a qualified plumber.
3. Condensate Drain Lines
Heat pumps and air conditioners are equipped with condensate drain lines. As the warm return air passes by the cold evaporator coil in the air handler, condensation forms and needs to be drained to the exterior of the home. Sometimes the drain lines leak, and duct tape isn’t going to stop it. A qualified HVAC contractor can repair the drain line is a snap. Leave it to the pros.
4. Shower Walls
If you want mold festering in the voids behind your shower, then by all means use duct tape to repair damage in your shower walls.
5. Dryer Vents
Boy scouts collect lint to start fires on their camping trips. If you want to spread fire starter in your crawlspace, attic, or walls, go ahead and use duct tape to secure you dryer vent.
and last but, not least…
Duct tape should never be used for…
These duct splices are held together by duct tape only. Don’t let the name fool you. Duct tape should never used for ducts, and these splices are destined to fail. Duct splices like this should have a metal sleeve between the two ducts, and the ducts should be secured to the sleeve with clamps.