Animals can be a major destroyer of flex based heat vent ducts. Cats sometimes turn a minor leak into a major excavate. The house stays cold. The beast stays warm. And your heating bill climbs. Leaks also permit dust, mildew, and under house odors to seep into the living quarters. Collapsed ducts restrict airflow, increase energy costs, and overwork the mechanical components of your heating and cooling units. When motors and blowers overheat, unexpected repair costs soon follow. One more important point: a heated crawlspace can attract vermin.
Warning: Flex duct is not difficult to replace, but it must be worked properly so as to prevent leaks and maintain correct airflow.
1. Starting inside the home, remove the heat register vent cover.
2. Confirm that the register boot is firmly attached to the flooring. If not, make any necessary repairs now.
3. Gather appropriate tools: light source, snips, scissors, aluminum tape, multi-purpose screwdriver, tape measure, box cutters, 4” metal clamps, joist hangers, mastic sealant, and the box of replacement flex duct.
TIP: You can use ten-penny nails and coat hangers.
4. Beginning at the end of the heat register boot, remove the existing flex duct. Noting the current path of installation, proceed to the duct’s source, and then remove that connection as well. Cut a length of the new flex duct so that it is five or six inches longer than the old. Discard the old.
5. Peel back the jacket and insulation from the core of your new duct.
6. Back at the existing register boot, slip the duct core over the existing pipe. Push tight, and then hold it in place with a few wraps of tape. Bind the edges with a metal clamp. Apply mastic sealant.
7. Pull the jacket and insulating back over the core. Wrap twice with tape. Apply mastic sealant.
7. Maintaining the original path, stretch the new flex to the source of air output. Attach it in the same manner as the other end.
8. Examine your work and apply hangers and support where needed.