Your thermostat’s set at 72. The upstairs bedroom’s sitting at 79. Somebody’s hauling a box fan up the stairs again, and somebody else is already talking about a bigger AC.
Don’t buy the bigger AC just yet. In most Plano attics I climb into for a hot-room call, the AC unit’s doing its job just fine. The air’s getting lost on the way.
Why One Room Stays Hot
Plenty of Plano houses were built in the ’80s and ’90s. Flex duct in the attic, almost every one. Give that duct thirty-some Texas summers at 130-plus degrees and the insulation jacket gets brittle. The cheap cloth tape on the joints just quits.
Then it sags. Straps supporting the flex duct too far apart and it hangs like a hammock, and each dip chokes a little more air before it reaches the room at the end of the line. Which is usually the back bedroom.
Worst one I remember, a supply run lying loose on the attic floor. Cooling the rafters. The guy’d had a hot office for six years and figured that room was just like that.
What New Ductwork Fixes
If the problem is distribution, new ductwork fixes it. Good ductwork installation means every run gets sized to its room. A bedroom with two west windows needs more air than a hall bath. A lot of old systems give them the same.
Game room over the garage in west Plano. Wouldn’t go below 80 in August.
One skinny run fed it from clear across the attic, and there was no return in the room at all. We put in properly sized new ductwork and cut in a return. Mastic on every joint.
When I went back to check it, the room was within two degrees of downstairs. She hadn’t touched the thermostat once. Her son moved his stuff back up there that weekend.
When It’s Not the Ducts
New ductwork won’t fix everything, and I’d be lying if I said otherwise. If the AC’s undersized or the blower motor’s dying, perfect ducts just spread not-enough air around very evenly.
A room under thin attic insulation, or one with old single-pane glass taking the afternoon sun, has a heat-gain problem. Ducts can’t outrun that.
So before we quote anything, we check static pressure and put a thermal camera on it, which takes about an hour. You can see on the screen where heat’s coming in and where cold air’s leaking out. Some days the whole fix is one crushed run, or a damper somebody shut years ago and forgot about. I’d rather tell you that than sell you a duct system.
Patch It or Replace It All
Depends what’s up there. One or two bad runs, we replace those and leave the rest. If it’s original 1988 flex duct with insulation flaking off every section, patching it is throwing good money after bad. Most houses land somewhere in between.
Full replacement on a typical two-story runs one to two days. Plano wants a mechanical permit for it, too. The inspector checks support, sealing and sizing, which is a big part of why I tell people not to DIY this. Bad seals in an attic pull dust and insulation fibers right into your bedrooms.
Get the new ductwork right, though, and the whole system gets more efficient. You quit paying to air-condition your attic.
Get It Checked Before Next Summer
Every month this drags on, the system runs longer chasing one room. That’s wear on the compressor you’ll pay for eventually. We’re Not Comfortable Until You Are, and that goes for the back bedroom too. Call Total Air and Heat at (972) 881-0020 and we’ll find out what’s really going on before anybody says the words “new ductwork.”
Questions We Get a Lot
Is it my ducts or is it my AC
Could be either. Could be both. If a couple vents are weak and the rest blow fine, I’d bet on the ducts. Warm air out of every vent is usually the equipment.
How long is new ductwork supposed to last
Somewhere around 15 to 25 years for decent material installed right. Plano attics are rough on it, so cheap flex can give out sooner. How well it’s hung and sealed matters about as much as what it’s made of.
Can’t I just close the vents in the cold rooms
People try it all the time. Close too many and pressure builds up in the system, which is hard on the blower and can freeze your coil. More air leaks out the bad joints, too, so the hot room barely notices.
Do I need a new AC too or just ducts
Not necessarily. A newer unit that runs fine can stay put, and new ductwork on its own might be the whole fix. If the AC’s close to done anyway, doing both at once saves a second trip into the attic.
Will all the rooms be the same temp after
No, and be suspicious of anybody who promises that. A room over the garage is going to run a little warm in a Texas August no matter what. Within two or three degrees of the rest of the house is a good result.
Oh, and check your filter before we come out, and if that fixes it, cancel. Won’t hurt my feelings.
