AC Duct Work and Additional Return

I would suggest waiting till winter. No one's going to do a correct job in 130° attic.

Also reach out to Delta T for a quote.

Outrageous!

Get more quotes in winter as previous poster suggested.

I had all ducting and AC unit replaced two years ago for $12K.

Less than 2 years ago, I had all duct work replaced as well as an additional 12x12 return installed. 17 registers, an existing return, and the new return was a little under $6k. This was in July in South Louisiana, so no discount on the work

ETA: One Hour is a trash company.

Do you currently have rigid ducts or flex ducts? I ask because I have a 30 year house in BR and the duct work is rigid.

Rigid ducts can re-sealed and re-insulated for what I’d assume a significantly reduced cost. Flex ducts would be replaced.

Biggest thing I would want to know is whether the ducts are adequately sized for a 5-ton system - duct work is often undersized, and the fact you think you need an additional return duct, and you likely do, suggest that might be the case. Put a 5 ton system on ducts designed for 4 tons of air flow, and you get 4 tons of cooling capacity.

As an aside, I had a HVAC change out 3 years ago. As the techs did the change out I had chance to look inside the ducts at the supply plenum and they were clean as whistle. I also had a duct leakage test before the change out and air leakage met current codes by a good margin so no work needed on the supply side ducts, but I also was about 1/3 low on return air capacity, so they added another return - flex was used for that which I was OK with. It did make a difference on comfort.

I agree with others - price seems high, but you haven’t provided much details and also try to hold off until winter if possible for the crews to have a good work environment. I had my change done in Feb for that specific reason.

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Learn me on this please! I need to replace a good bit of ours

Have rigid ducts from the 70s. Replace or reinsulate as described above?

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First thing you need to do is remove the existing insulation to check the galvanized duct work to make sure it is not compromised with holes from rust and make sure all the joints where the pipes come together are still well connected. Even though it is galvanized pipe, it is very thin and can be easily damaged.

They should all be screwed together with self-tapping screws and each joint wrapped with duct tape to make an air tight seal. If the pipe is bad, then get the same size pipe to replace it. Joval metal pipe simply interlocks when assembled to form a 5 ft. x whatever diameter pipe you are needing for the run.

As for the insulation, it comes in large 4 ft. wide rolls and is easily cut with a utility knife to the proper size to fit around the pipe. To secure it to the pipe you want to have enough insulation to completely surround the pipe with enough to make a neat fold along the length of the pipe and use a staple gun to seal the seam. It is a special staple gun designed for duct work. When wrapping the pipe, don't compress the insulation too much as it compromises its ability to insulate-----you want it snug, but not tight.

Considering your duct is 50 years old, you may need to change out some of the pipe and I would definitely change out all insulation.


I'm pretty sure there are some u-tube videos on this subject you can watch to clarify things.

For reference, new Return location, replace current Return and new duct work was right at $15k for me 2 years ago. Burkhardt.