The cooling you are losing into the attic is cooling you already paid for. This is the job that gets it back.
Serving Phoenix, AZ
# ROC 102297
Rated by BBB
Duct sealing closes the leaks in your duct system so the air your air conditioner cools actually reaches your rooms. Duct repair fixes runs that are damaged, disconnected or collapsed.
If you only ever do one thing to the ductwork in a Phoenix home, this is the one. Cleaning improves what you breathe. Sealing changes what you pay and how well the house cools, and in this climate the numbers are not small. Most Phoenix homes run their ducts through an attic that reaches [150] degrees in summer, which means every leak is losing conditioned air into the worst place in the building, and every gap on the return side is pulling that superheated air back into the system.
A house can have a brand new high-efficiency air conditioner and still cool badly and cost too much to run, entirely because of what is happening above the ceiling.
The single most common cause is a disconnected or collapsed duct run. Flex duct works loose at a connection, or gets crushed by something set down on it in the attic, and the air meant for that room is going into the attic instead. It is common, it is invisible from inside the house, and it is usually a straightforward repair.
Neighbours in similar houses paying noticeably less is the signal. Duct leakage in an unconditioned attic wastes cooling on both sides: conditioned air escaping out of the supply, and 150-degree attic air pulled in through the return. The system then runs longer to cover both, and you pay for all of it.
If the equipment tests healthy and the house still falls behind, capacity is being lost between the air handler and the registers. This is what duct leakage looks like from the thermostat.
Return-side leaks pull unfiltered attic air straight into the system, past the filter, and into your rooms. If you have upgraded the filter and the house is still dusty, this is very often why. It is also why sealing sometimes does more for a dust problem than filtration does.
Partly physics, since heat rises, and partly ductwork. The runs feeding upstairs are usually longer, they pass through the hottest part of the attic, and they lose the most on the way. Sealing and insulating those runs is the fix that works before anyone reaches for a bigger system.
Sagging flex duct restricts airflow even when it is intact, because every dip is a place air has to fight through. Torn insulation on an attic run means that run is delivering warm air no matter how well the equipment is working.
Sealing before a replacement is the right sequence. It sometimes means the new system can be a size smaller, which costs less to buy and less to run, and it always means the equipment delivers what it is rated for.
Two reasons, and they compound.
The attic is brutally hot. A duct leak in a mild climate loses conditioned air into a space that is roughly room temperature. A duct leak in a Phoenix attic loses it into a space at [150] degrees. The supply-side loss is the same volume either way, but the return-side problem is far worse, because instead of drawing in neutral air the system draws in air hotter than anything outside the house.
The cooling season is five months long. A leak that would cost you a modest amount over a short summer costs you continuously from May through September here. The same defect is simply worth more money in this market.
That combination is why duct sealing has a shorter payback in Phoenix than almost anywhere in the country, and why it is worth doing before spending on equipment.
Measured, not guessed. Static pressure across the system, airflow at the registers, and a physical inspection of the runs, connections, plenums and boots. Return-side leakage gets the same attention as supply-side, which is not always the case.
Sealing a disconnected duct is pointless. Reconnect what has come apart, replace crushed or torn sections, support sagging runs properly, and reattach boots that have pulled away from the ceiling. Physical repairs come before any sealing.
[Mastic and mesh, or the client’s actual method] at joints, takeoffs, plenum connections and register boots. Not duct tape. Duct tape fails in attic heat, usually within a couple of seasons, and it is one of the most common things we find on top of previous “repairs”.
The connections at the air handler leak more often than the runs do, and they are easy to overlook because they are not out in the attic. The cabinet itself is worth checking too.
An attic duct with degraded or missing insulation delivers warm air even when it is airtight. Re-insulating those runs is part of the job, not an upsell on top of it.
Static pressure and register airflow re-measured after the work, and compared against the readings from the start. You get both sets of numbers. This is the part that proves the job did something, and it is the reason we take the readings at the beginning rather than just at the end.
Three different answers and it is worth knowing which one you are being sold.
Sealing is right when the ducts are physically sound and losing air at the connections. That describes most Phoenix duct systems over ten years old, and it is the highest-value duct work there is.
Repair is right for isolated physical problems: a disconnected run, a crushed section, a boot that has pulled loose, torn insulation on a few runs. Targeted, and it does not require touching the rest of the system.
Replacement is right when the flex duct inner liner is deteriorating throughout, when the system was badly designed and cannot deliver what the equipment needs, or when the duct sizing will not support a new air conditioner. It is the biggest of the three jobs and it is over-recommended in this industry, so ask for the readings behind it.
If you are not sure which you need, start with an inspection.
You may have seen sealing done by blowing an aerosol sealant through the duct system so it collects at the leaks from the inside. It is a real technique and it works well in some situations, particularly where ducts are hard to reach physically.
[Confirm whether CMI-AIR offers aerosol duct sealing. If not, this section should say plainly that we seal manually and why that suits most Phoenix homes, rather than dismissing a method we do not offer.]
Manual sealing with mastic at the connections is the approach that suits most Phoenix homes, because the leaks here are usually at accessible joints and connections rather than distributed through inaccessible runs, and mastic in an attic outlasts most alternatives.
Call (602) 437-0066 or use the form. If the reason you are calling is one specific room, mention which one, because that narrows down where to look immediately.
In a Phoenix home with attic ducts, it is usually the highest-value work you can do on the system. You are losing conditioned air into a 150-degree space for five months a year, and sealing stops it. It typically improves comfort in the rooms that were worst as well, because those are usually the ones on the leakiest runs.
Sealing, for two reasons. It saves money where cleaning mostly improves air quality, and cleaning a leaky system means the leaks pull dust straight back in. If you are doing both, seal first and clean second and the cleaning lasts.
Duct tape is the one thing not to use, which is a genuinely confusing name for it. The adhesive fails in attic heat, usually within a couple of seasons, and we routinely find failed tape over joints somebody sealed years ago. Foil tape rated for ducts is better, and mastic is better again. The bigger issue is that most leaks are at connections in places that are unpleasant and awkward to reach, which is why this tends not to be a satisfying DIY job.
Most single-system Phoenix homes are [one day]. It depends far more on attic accessibility than on the size of the house. A low-clearance attic in summer is slow work.
It should, and it is the duct job most likely to. How much depends on how leaky the system was to begin with, which is why we measure before and after and give you both numbers rather than quoting an industry average at you.
Common signs: a room that will not cool, a cooling bill out of step with similar houses, a dusty house despite a good filter, the system running constantly on hot days, and visible gaps or disconnected runs if you can see any of the ductwork. None of them is proof on its own, which is what the static pressure and airflow readings are for.
Often, yes. Duct sealing is not always done well on new construction, and flex duct connections can work loose in the first few years as the building settles and the attic goes through heat cycles. A newer house is not a reason to assume the ducts are fine.
Sometimes, and it is a real reason to do the sealing before a replacement rather than after. If a meaningful share of your capacity is currently going into the attic, fixing that lowers the load the new equipment has to cover. A smaller system costs less to buy and less to run.
CMI-AIR is the residential division of Consolidated Mechanical, a local, family-owned commercial air conditioning company with more than 30 years of experience.
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