The Problem Nobody Looks At
Homeowners replace furnaces, upgrade thermostats, and buy bigger air conditioners to fix comfort problems. Almost nobody looks at the pipes connecting it all. That's backwards. Your ductwork is the delivery system for every dollar of heating and cooling you buy, and in a lot of houses it leaks like a screen door.
Field studies across the industry have found typical homes losing a significant chunk of their conditioned air through duct leaks, commonly in the 20 to 30 percent range, and worse in older systems. In the older housing stock east of Cincinnati, we regularly find ductwork that was assembled decades ago with cloth duct tape that dried out and fell off during the Reagan administration. Every gap at every joint is air you paid to condition, dumping into a basement, attic, or wall cavity.
How Rooms Starve
Duct leakage isn't spread evenly. The rooms farthest from the furnace, usually upstairs bedrooms and back corners of the house, are at the end of the longest duct runs with the most joints. By the time air fights through six leaky connections, there's not much left. So the bedroom over the garage is freezing in January while the hallway by the furnace is toasty.
Leaks on the return side are their own problem. A leaky return duct running through a crawlspace doesn't just lose air, it sucks in crawlspace air, complete with moisture, dust, and whatever else lives down there, and feeds it to your system. That's a comfort issue and an air quality issue in one.
And here's the expensive irony: starved rooms are why people get sold bigger equipment. A bigger furnace shoving air into leaky ducts just leaks more air, faster. The room stays cold and the bills go up.
Where do the leaks actually live? Mostly at the joints. Every place a branch duct meets the trunk, every elbow, every boot where a duct meets a register, and every seam in a panned joist return, which is that old-school trick of using the floor joists themselves as a return duct. Panned returns are everywhere in older east-side basements and they leak by design, because wood shrinks and nothing about a joist bay was ever airtight. Flex duct adds its own failure points at every strap and connection.
Signs Your Ducts Are Leaking
- Big temperature differences between rooms, especially rooms far from the equipment.
- Weak airflow from certain registers. Hold a tissue up. If it barely moves, that run has a problem.
- High Duke Energy bills relative to similar-sized homes.
- Dust that comes back days after cleaning, or a musty smell when the system runs.
- A basement or attic that's oddly warm in winter or cool in summer. That's your conditioned air, delivered to the wrong customer.
- Visible gaps, disconnected runs, or crumbling tape on any exposed ductwork.
How Duct Testing Works
You don't have to guess. A duct leakage test puts a number on it. The system's registers get sealed off, a calibrated fan pressurizes the ductwork, and the equipment measures exactly how much air escapes. Before-and-after testing means you can see what you're paying for. This is the same test new construction gets for code compliance, applied to your existing house.
We're big on measurement over stories. Same reason we photograph heat exchanger inspections: you should see proof, not take a tech's word for it. A duct test gives you a hard number before anyone talks about spending money on sealing.
Sealing Options, Including Aeroseal
There are two main approaches, and the right one depends on your house.
Manual sealing. For accessible ductwork, a tech seals joints by hand with mastic, a paint-on sealant that actually lasts, unlike the cloth "duct tape" that ironically fails on ducts. Exposed basement runs in a typical Anderson or Milford home respond well to this. It's labor, but it's straightforward and effective where you can reach.
Aeroseal. For ducts buried in walls, ceilings, and chases, which is most of the duct system in most houses, there's Aeroseal. The registers get blocked off, and a fog of sealant particles gets blown through the ductwork under pressure. The particles ride the escaping air straight to the leaks and build up at the edges of each gap until it closes. It seals leaks nobody could ever reach with a brush, and the process measures leakage in real time, so you watch the number drop and get a printed before-and-after report.
Most houses end up with a combination: mastic on the accessible stuff, Aeroseal for everything hidden. You can read more about how we approach it on our ductwork services page.
Is Sealing Worth the Money?
If your test shows serious leakage, sealing is one of the better dollar-for-dollar improvements in this business, because it fixes comfort and bills at the same time and it doesn't wear out. It also right-sizes your future: equipment sized for a tight duct system can often be smaller and cheaper than equipment sized to overpower leaks. If your leakage tests low, we'll tell you, and you just bought useful peace of mind for the cost of a test. Our techs are salaried, not commissioned, so nobody's incentive is to find leaks that aren't there.
If you've got rooms that never feel right or bills that don't match your thermostat habits, get in touch and we'll test instead of guess. We run duct diagnostics across the east side, from Mount Washington to Loveland.