The last two feet of every run — the boot in the ceiling, the register on it, the return grille in the hall with a filter behind it — is where the dust you can see collects and where a cheap cleaning begins and ends. On a real job it is one step of eight. On its own it is a register wipe-down with a price tag.
Pull a supply register in a Houston bedroom and the boot behind it — the sheet-metal box the flex duct attaches to — usually carries a gray-brown ring of dust and lint where the air turns the corner and slows down. The register face collects more from the room side. Around the opening on the ceiling texture there is often a faint dirt shadow where the air has been leaking around the boot rather than through it, which is a sealing problem rather than a cleaning one and worth mentioning to the crew.
On a proper job every register comes down, gets washed, and goes back up; the boot is brushed and vacuumed toward the plenum with the system under negative pressure; and the gap around the boot is noted. That last item is the useful one. Houston boots are rarely sealed to the drywall, and the gap pulls attic air — at 130°F and full of insulation fibers — into the airstream every time the return side pulls harder than the supply side pushes.
Supplies push clean, filtered air into rooms. Returns pull whatever is in the rooms — pet hair, skin, carpet fiber, drywall dust, cooking residue — back toward the air handler, and everything that the filter does not catch, plus everything that gets around the filter at its edges, lands in the return run and the return plenum. A return grille is bigger, a return run is bigger, and the material in it is heavier. That is why returns cost more per opening than supplies, $40 to $75 against $25 to $50, and why a job that does the supplies and skips the returns has done the easier, cleaner half and left the other.
Most Houston homes have one or two returns per system, sometimes a filter grille in a hallway ceiling, sometimes a filter slot at the air handler itself and a bare grille in the wall. The crew should be able to say which yours is, because it decides where the filter lives and where the dirt stops.
This is the step the coupon specials perform. A technician with a shop vacuum and a small brush works each supply register from the room, sprays a deodorizer into the boot, and moves on. Nothing is under negative pressure, so what is knocked loose beyond the reach of the vacuum goes down the run or back out into the room. The returns are usually skipped or added as an on-site charge. The plenum is never opened. It is a register cleaning sold as a duct cleaning, and it is the reason the phrase “whole house” means nothing on its own.
The honest version of this service is as part of a whole-home cleaning, where the openings are the ends of runs that are being worked from the plenum side. As a stand-alone, it is only worth buying for a house whose ducts are clean and whose registers are not, which is a wipe-down you can do yourself.
Yes, and it is a fair Saturday job: registers off, washed in the sink, boots vacuumed as far as the hose reaches. What you cannot do is put the system under negative pressure, which is what separates that from a duct cleaning.
Air leaking around the boot rather than through it, carrying attic dust with it. Sealing the boot to the drywall fixes it; cleaning does not. Point it out to whoever comes.
At least one per system, usually one per floor. A house with one central return and closed bedroom doors starves the return side and pulls attic air through every gap it can find, which is a design problem and a common one here.
Openings are the ends of runs. A whole-home cleaning works the runs.
Where the material that gets past the grilles actually ends up.
Supplies $25 to $50, returns $40 to $75, on top of the per-system base.
Say what the registers look like and where the house is. The contractor covering your zone quotes the run, not just the grille.
Call (346) 586-0541 Describe the Job
Houston Duct