We will be straight with you on this one, because most pages about duct cleaning are written by people who sell duct cleaning.
You probably do not need it.
That is not a marketing position, and it costs us money to say. It is roughly where the evidence sits. The EPA looked at this and declined to recommend routine duct cleaning, noting that duct cleaning has never been shown to actually prevent health problems and that dust in ductwork does not necessarily mean the air in your house is unhealthy. Most of the particulate you breathe indoors comes from cooking, from outside, from your carpet and from you, not from a duct.
There are real reasons to have it done. They are specific, and most people who get sold duct cleaning have none of them. Here is the whole honest picture, and if you read to the bottom and still want it, the form will put you in touch with someone who will do it properly.
When it genuinely is the right call
Four situations, and they are not subtle. You will know if you are in one.
- Visible mold growth on the inside of the duct or on the sheet metal of the plenum. Not a smell, not a suspicion. Growth you or a technician can see. Worth noting that a great deal of what gets pointed at as mold is dust, and that if there is mold in your ducts, something is putting water there, and cleaning without fixing that is pointless.
- Vermin. Rodents get into attic ductwork in this city more often than people would like to think, and if something has been living and dying in there, you clean it or you replace it.
- Ducts genuinely clogged with debris, to the point that you can see it coming out of the registers.
- After construction. If you have just had a remodel and the crew did not seal the registers, there is drywall dust throughout that system. This is the most legitimate and most common good reason.
Notice what is not on that list. Allergies are not on that list. Dusty furniture is not on that list. “It has never been done” is not on that list, and it is the single most common thing said on the phone.
The $79 coupon
You have seen the ad. Whole house, unlimited vents, $79, sometimes $59.
Think about what has to be true for that to work. A real duct cleaning is a crew, a truck-mounted vacuum, several hours and access to every register in the house. Nobody does that for $79. The $79 buys a shop vac at a few registers and a technician in your attic, and the actual product being sold is what he finds up there. It is always something. There is always mold. There is always a recommendation for a “sanitizing” treatment at several hundred dollars, and frequently a system replacement quote follows.
A real, NADCA-standard cleaning of a Long Beach single-family house is $450 to $900. If you are quoted a fifth of that, you are not being quoted for the work. You are being quoted for the appointment.
Do not let anyone fog chemicals into your ductwork
The upsell is usually called sanitizing, or antimicrobial treatment, or fogging. Someone sprays a biocide into the supply ducts of the system that blows air at your family for the next decade.
Most products are not registered for that use, the EPA has been clear that chemical biocides applied to duct surfaces are a limited and specific tool rather than a routine add-on, and the benefit in a house with no mold problem is zero by definition. Decline it. If there is real mold, the answer is to find the water, fix the water, and clean or replace the affected duct. Chemistry does not fix a leak.
The Long Beach specific: your ducts may not survive the cleaning
This matters here more than in most cities and almost nobody mentions it.
In the post-war slab tracts around Los Altos, El Dorado Park and Bixby Highlands, the ductwork is flex duct in the attic and a lot of it dates to the 1960s. That is a thin inner liner on a wire helix, and after fifty years in an attic that hits 130 degrees every summer, the liner is brittle. Running a rotating mechanical brush through it does not clean it. It tears it.
So if you have old flex duct and you think you have a duct problem, cleaning is the wrong purchase and the right one is a look in the attic. Old flex duct that is sagging, crushed at the turns or disconnected at a boot is bleeding your conditioned air into the attic. That is a real, measurable, expensive problem, and it is a problem cleaning does nothing about. Replacing bad runs costs more than cleaning and it actually changes your utility bill.
What actually improves the air in your house
If the underlying goal is cleaner air rather than clean ducts, there are two things that work and one of them costs $30.
Buy a better filter and change it on a schedule you actually keep. A MERV 11 to 13 pleated filter captures a great deal of what a MERV 6 does not, and in a house near the 710 corridor or the port, where diesel particulate is a genuine and well-documented local issue rather than a talking point, that is the intervention with the real effect. One caution: a very restrictive filter in a system with undersized return ducts will choke airflow and cost you efficiency, so ask your contractor what the blower can take before you jump to MERV 13.
Then seal the ducts. Sealing is the thing duct cleaning gets confused with, and it is the one with a number attached. Mastic at the joints, or an aerosol sealing process, and afterward a HERS rater can measure the leakage and tell you exactly what changed. You cannot measure the result of a cleaning. You can measure the result of a sealing. That difference tells you which of the two is a service and which is mostly a feeling.
Questions we get
How often should ducts be cleaned?
There is no schedule, and any company that gives you one is selling a subscription. Clean them when there is a reason from the list above.
There is black stuff around my vents. Is that mold?
Usually it is dust, held there by static and condensation, and it is on the outside of the register where you can wipe it off with a damp cloth. Occasionally it is real. If you want to know rather than guess, a lab will test a tape sample for a modest fee, and that is a better use of $60 than a $600 fogging you were talked into by the person who diagnosed it.
We just bought a 1958 house in Los Altos. Should we clean the ducts before moving in?
This is the most sympathetic version of the question and the honest answer is still probably not. Have someone look at the ducts, by all means, because at that age the useful finding is usually that they are failing rather than dirty. If the previous owner smoked heavily or kept a lot of animals, cleaning is more defensible. If the ducts turn out to be original flex, spend the money on replacing them and you will feel the difference. You would not have felt the cleaning.
Still want it done, or want someone to look?
Tell us the neighborhood, the age of the house, and what made you start thinking about the ducts. If the real problem turns out to be something else, our Long Beach partner will tell you that. Related: AC repair, AC installation, furnace repair, or the Long Beach HVAC overview.