Should I replace old asbestos-wrapped ductwork while walls are open?
When walls are open during renovations, deciding whether to replace old ductwork wrapped in asbestos depends on whether there is actual damage, though disturbing it raises safety and sizing concerns. Replacing the ducts can avoid future issues, but uncertainty about handling asbestos and potential sizing constraints with the existing unit makes homeowners hesitate to tear it out.
What the numbers show
Counted from the threads quoted below. How we count
- Most of it landed at once — the busiest month was September 2026, with 16 people.
- This comes up 24.3× more often in r/hvacadvice than across the site as a whole.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
Found another way around this?
Share your steps and trade-offs so fellow engineers don't have to reinvent the wheel. No account required.
- 1Leaving the old ductwork undisturbed behind new drywall to avoid expensive abatement costs and potential fiber release.Did this help you?
- 2Attempting to adjust blower speed taps to lower CFMDid this help you?
- 3Adding registers to framing areas to let the space breatheDid this help you?
- 4Installing carbon monoxide detectors on each floorDid this help you?
- 5Waiting for the unit to fail or seeing how it performs during the upcoming seasonDid this help you?
- 6Using duct tape as a temporary connection for misaligned ductwork openingsDid this help you?
- 7Buying space heaters to combat cold temperaturesDid this help you?
- 8Attempting the ductwork repairs as a do-it-yourself project to save moneyDid this help you?
- 9continuing annual maintenance and combustion tests until a major component like the heat exchanger diesDid this help you?
- 10squeezing out another heating and cooling season safely while saving money for eventual replacement equipmentDid this help you?
- 11Seeking additional quotes from different companiesDid this help you?
- 12Looking for mom and pop shops or private contractors with lower overheadDid this help you?
- 13Getting a second opinion or quality check from another technicianDid this help you?
- 14Staying with a single-stage system (like a 14 SEER2) that is compatible with existing ductwork to avoid high upgrade costs.Did this help you?
- 15Asking AI or HVAC professionals for adviceDid this help you?
- 16Leaving the existing line set in place unless it looks damaged or is for a mini-split systemDid this help you?
- 17Replacing everything at once depending on the length of the run and age of the linesetDid this help you?
- 18getting a second opinion from another HVAC technicianDid this help you?
- 19building a soffit around the ducts to hide themDid this help you?
- 20leaving the panned framing intact and finishing around itDid this help you?
- 21Replacing only the damaged compressor or partDid this help you?
- 22Replacing just the condenser and evaporator coilDid this help you?
- 23Checking manufacturer warranty coverage for partsDid this help you?
- 24Resetting the furnace to see if it continues to function normallyDid this help you?
- 25Trying to get another year out of the existing system due to budget constraintsDid this help you?
- 26Relying on a struggling heat pump during very hot weatherDid this help you?
- 27Seeking advice from technicians or online communitiesDid this help you?
- 28Reusing the existing line set as proposed by contractorsDid this help you?
- 29Replacing only the failing or older unit while keeping the fully functional older unit until it fails.Did this help you?
- 30Hiring a cheap installer to stitch a new system onto the existing damaged ductsDid this help you?
- 31Replacing individual duct runs only as they are exposed during other remodeling projectsDid this help you?
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“Prepping for an offer on a foreclosure and trying to get ducks in a row.”source ↗
“Systems original to 2007 and both needing significant service (board replacement, recharging, air handler replacement, tray replacement etc) but total replacement seems to be the smarter choice.”source ↗
“Quoted about $24k to stick with 80% gas furnace (and that wouldn't be rebate eligible) up to $38k for two stage heat pump”source ↗
“Quoted 7k to fix the duct work.”source ↗
“Would this duct work cause the unit to not be cooling correctly?”source ↗
“Also, could this be DiY?”source ↗
“I've had 4 quotes. Only one installer recommended replacing the line set.”source ↗
“HVAC guys, what is the way to go ?”source ↗
“Had a HVAC tech come out to do some maintenance. While doing so he found a few issues and was looking for some thoughts if it is that time for a full replacement.”source ↗
“I was hoping to not need to replace the whole entire unit just due to the ducting sizing.”source ↗
“Is it possible to just replace/lower the blower Cfm somehow?”source ↗
“My gas furnace is a Goodman GMH950904CXAB high efficiency 95% AFUE, two-stage gas furnace with a 92,000 BTU . 19 years old I’m looking for advice for the upcoming season.”source ↗
“If there were any issues with the heat exchanger/ potential carbon monoxide leaks would the unit shut down first on a unit like this?”source ↗
“Should I replace now or wait and see how it performs?”source ↗
“I HAVE TO replace the furnace THIS YEAR because it's cracked & dangerous, but I can't tear out and & replace the WHOLE SYSTEM of ductwork as planned (financial issue) until at least next year.”source ↗
“My furnace is cracked because my intake ductwork is 40% the size it needs to be AND the output ductwork is only 40-50% the size needed.”source ↗
“We have a Coleman Echelon 9VSeries furnace that was installed in our home in Kingston Ontario Canada back in 2005. It is about to enter its 22nd heating season. It has been serviced by the same technician every fall for most of its life. While we have had no major problems or concerns with it to date, other than replacing the blower a couple years ago, we wonder if we should replace it or not before something major fails.”source ↗
“Once you hit that 20 year mark, you start taking a gamble. If the furnace was installed properly, and maintained well over the years you might be able to overshoot that life expectancy for a good while. That being said you *are* gambling and there's always the chance you could be without heat when you need it...”source ↗
“I need to decide between a 14 SEER2 Rheem RA14AY and a 2-stage 16 SEER2 Rheem RA16AY system.”source ↗
“For the single stage 14, I'm being told that my current ductwork is in good condition with the right CFM and will work fine but to upgrade to a 16, all the ductwork must be replaced.”source ↗
“Beyond the price difference between the systems, the ductwork is an additonal $5000 and I'm just not sure it's worth that much expense relative to the energy savings.”source ↗
“I quoted me a new system with ductwork and moving it to the attic at 14-15k.”source ↗
“Any thoughts or recommendations? I’m thinking about getting a second opinion”source ↗
“I'm redrywalling my basement and want to know if I should redo these ducts.”source ↗
“Should I redo these 2 framing ducts as well?”source ↗
“I had a tech look at my AC and they said it showed signs of a grounded compressor with 309 amps going to the compressor at start. I am just wondering if it makes sense to replace the furnace with the ac unit at the same time or just the condenser and evaporator coil.”source ↗
“It’s been running normally for 24+ hours now…but given all of this…am I foolish to try to get another year out of this thing?”source ↗
“Kid in last year of college and I don’t have it in the budget!”source ↗
“Should I have my line set replaced?”source ↗
“So I guess my main question is is if we should have the line set replaced as well?”source ↗
“I think it's a good idea to replace both units, as the price difference is <$7k even though the basement unit is working fine but it's quite old.”source ↗
“My wife disagrees and says we should only do the attic unit.”source ↗
“Looking for some opinions and advice on replacing both units or just the attic unit.”source ↗
“My question is- while we have the walls open, should we be replacing our ductwork as we work through each room? I’m assuming this is all wrapped in asbestos duct paper so I’m just not sure if I should leave it be as I see no real damage like holes or leaks, or if it’s for the best to replace it while we’re here.”source ↗
Where this came up
People with this problem also raised
- 14Should I reuse an old plumbing drain or replace it?
- 3Should I replace my attic fan when getting a new roof?
- 2How do I connect a flanged boot to rectangular duct?
- 7Should I replace my oil boiler or repair it?
- 3Do rusty pipes need to be replaced if they aren't leaking?
- 3Should I replace the AC condenser when replacing the compressor?