when you replace your furnance& AC units

[irisblue]

do you get new ducts? I am looking to replace my 20 yr old units this winter. Thanks

[jeff47]

1. Usually not.

Because replacing your ducts requires opening an enormous percentage of your walls and ceilings.

Instead, the usual practice is to replace your HVAC units with ones that are compatible with your old ducting.

If there is something actually wrong with your ducting, such as poor balance between rooms, then you might want to consider it. But that means you're now replacing your HVAC, your ducts, a significant percentage of your drywall, and repainting the entire interior of your house.

[CaptainTruth]

2. I agree, usually not, if your existing ones are in good condition.

It's an excellent time to have them cleaned out.

As for drywall & ducts in walls (mentioned in the post above), that depends on where you live, which can influence the way your house is constructed. Here in FL most houses are slab-on-grade (built on a concrete slab) with concrete block exterior walls (for hurricane protection). There are no HVAC ducts in walls, they're all in the attic. That makes it a lot easier to install new ducts, but the low roof pitch (for less wind load, & we don't need to shed snow from the roof) means it's "fun" crawling around up there trying not to hit your head ... which I always do a few times every time I have to work in a FL attic.

[Warpy]

3. Ducts usually don't wear out

unless they're asbestos wrapped nightmares, in which case it will cost a fortune to get them ripped out and replaced with something that doesn't give you cancer.

The one thing that ductwork does need is occasional cleaning, dust does tend to build up in them even with frequent filter changes.

[sinkingfeeling]

4. No. Sometimes they may rewrap them with insulation.

[Thor_MN]

5. No, but often the sheet metal above the furnace needs to be custom built

to mate up with your ducts. Sometimes they are able to reuse it, whatever it is called (I'm sure it has a name), but often the furnace and new AC coils won't work with the existing sheet metal.