Maintenance · May 7, 2026 · By Doug Kelley, Master Licensed HVAC Technician

The Hidden Money Leak: 7 Signs Your Ductwork Is Wasting Your Heating and Cooling

You can buy the best equipment made, and if the ducts leak, you are paying to condition the crawlspace. Studies consistently find typical duct systems leaking 20 to 30 percent of the air they carry, and the older housing stock of the upper Shore, with ducts snaking through vented crawlspaces and unconditioned attics, sits at the leaky end. Here is how the problem shows itself.

The seven signals

• Rooms that never match: the far bedroom that is always hot in summer and cold in winter, because supply air bleeds out before arriving
• Bills that outgrew your usage, without a rate change to explain them
• A system that runs long or constantly to hold ordinary temperatures
• Dust that returns days after cleaning: leaky returns vacuum crawlspace and attic dust into the system and distribute it to your shelves
• Musty or earthy smells when the blower runs, meaning the return side is breathing crawlspace air
• Visibly disconnected, crushed, or dangling runs anywhere you can see ductwork
• A house that gets dusty, humid, or smelly specifically when the fan runs: the ducts are talking

Why leaks cost double here

Supply leaks dump air you paid to condition into spaces you do not live in. Return leaks are sneakier and often worse: they pull unconditioned air in, and on the Shore in summer that means drawing thick humid crawlspace air into the system, which loads the AC with moisture it then spends capacity removing. Return leaks in garages or near combustion equipment can also pull genuinely unhealthy air into the house, which moves this from a money issue to a health one.

What fixing it involves

Real duct sealing means accessible joints sealed with mastic, the paint-on sealant that lasts decades, not the cloth duct tape that ironically fails on ducts within a couple of years. Disconnected runs get remade and supported properly, crushed flex gets replaced, and ducts in unconditioned spaces get insulation so the air arrives at the temperature it left. Sometimes the fix includes right-sizing chronically undersized returns, which improves every other thing the system does. It is unglamorous work with glamorous results: systems effectively gain back capacity you already paid for.

If some rooms in your house have simply never worked, the answer may be in the crawlspace rather than the equipment. We look at ductwork honestly on every install and happily on its own: (443) 310-0206.