Patching some ductwork...

[Wade Lippman]

My humidistat is broken. Both the new and old one are 3" vertical and 5" horizontal. There is a 5" vertical by 3" vertical hole in the ductwork, presumably from an even older humidistat. Whoever installed the current one covered the hole with duct tape, with a hole cut for the sensor. I was intending to do the same, but the new sensor is way over to the side and won't really work with the existing hole. (the old one has a sensor in the middle, so screws went on either side of the hole)

I have some aluminum flashing material. I'd like to put that over the hole with sheet metal screws, and seal the edges with duct tape. It is on the return, so there will be suction and cool air. Any problem with that idea? Obviously my HVAC knowledge is thin.

[Bill Dufour]

Use any seal but duct tape. Duct tape will fail in one year or less.
Bill D

[Wade Lippman]

Use any seal but duct tape. Duct tape will fail in one year or less.
Bill D

I have the aluminum tape that actually works on ducts and can certainly use that, but.... the duct tape that I pulled off to expose the hole was about 7 years old and it was in pretty good shape. I thought duct tape was only bad on the hot air ducts rather than the return duct I am dealing with. No?

[Jim Becker]

Yes, you can use flashing material or similar to cover the hole no problem. While sheet steel is obviously more durable, the aluminum will work just fine for a hole of that size. Seal with foil tape once you have it screwed in place.

[George Yetka]

You can grab a piece of sheet metal from HD/lowes for less than the cost of a roll of duct tape. Use a sealant and throw 4 sheet metal screws in it. Once this is in drill an appropriate sized hole for your new sensor. This will last forever.