insulate the heat duct?

I have a large unheated crawl space under my family room. The family room is cold in the winter and warm in the summer. I'm thinking about wrapping the heat duct that runs through the crawl space under the room. Will this make a difference? Cost effective? If so, what kind should I use?

P.S. - The heat duct runs about 18' though the crawl space.

Here is a photo of the crawl space (if it worked).

I'd like to hear the pro's advice on this. I have ducts running in my attic- only the small ones are insulated.

Both of you guys need to find out exactly what you have there.
Rburt most likely has "internally" insulated sheet metal ducts, although I don't see "tack pins" in his pic.
My eyes are not what they used to be!


If not,........it would pay you to use duct wrap, even though it is in a crawlspace that appears to be well insulated.
Drop a section, by taking off the drive connectors, and see if there is insulation inside of the sheet metal.

Southernman,.......you may have a similar circumstance.
Externally wrapped round pipe "takeoffs", originating from an internally lined sheet metal trunk,.........or from a ductboard trunk.

Details are needed to determine if your work, and expense will be a plus.
Obviously more insulation can't hurt, but it is a cost,.....effort vs. expected savings issue.

What is probably as much of a benefit is to ensure there are no air leaks in the ducts - seal them properly so you get all of the conditioned air you've paid for.