Clean the ducts after a major renovation - even then, ours spouted a fine dust for several weeks after we had our kitchen remodeled. Otherwise, air filters (and cleaners if you have them installed) keep the ducts open and clean.

I remember being told by a professional that cleaning air ducts was a total waste of money and time. Perhaps it is a necessity after a major renovation but not as a regularly scheduled thing.

I vacuum my intake registers monthly, but I haven't ever done inside the ductwork.

I just bought a house and the last owner seemingly never changed the furnace filter. It was one of the "washable" kind and literally caked SOLID with dirt. I'm having someone come by to clean the ducts out in a few weeks once the smell from floor refinishing dissipates and have also ordered a bunch of disposable furnace filters online (odd sized filter required that isn't sold in the big box stores.) I would say cleaning the ducts is good when you buy a new house and after major construction. Otherwise, like others have said, frequent changes of furnace filters should take care of it on a regular basis.

Hmmmm. Our house was built in 1994. We are the second owners, purchasing in 2006. We have never had the ducts cleaned, but have recently been considering it. We did have the kitchen remodeled 2-3 years ago, but have always used and regularly replaced furnace filters at the return-air registers. We just put in a new geothermal furnace (indoor unit only----to replace the original) and our HVAC guy who has always serviced this home said we do not even need to use those return-air filters because the new furnace has a filter in it which we "need" to take out and clean/wash once a year. What do y'all think? Personally I would still like to use those filters, but supposedly that will just affect the furnace efficiency??

For everyone who says it is a scam, would you recommend it if moving into a house with prior cats if allergic? Would it help?

My father sold heating and air conditioning systems for at least 40 years. When companies first started advertising duct cleaning services in our newspaper, he had a hissy fit, said it was a scam, and said that there was no reason for doing this unless a duct had somehow been damaged so that attic dust could get in. Just keep your filters clean.

It's not a scam. We had ours done several years ago in our older home and were amazed at what came out (my husband was present for the cleaning). Among others things, a dehydrate dead mouse appeared. The fact is, ducts do crack and rodents chew their way in. Unless you are crawling your attic or sub area regularly, you wouldn't know what's in your ducts. Poor air quality is the cause of illness. To me, it's worth it to do every so often. We are doing ours tomorrow and it's only been about 7 years since we had our system put in. But, we live on a dusty road, too.

ccaro4, yes, I would.

krismays provides exactly the example my father gave: damage to ducts allows dirt to enter them. At this point, they not only might need cleaning, but definitely need repair to eliminate the damage that allowed the dirt (and rodents!) to enter in the first place. So if your cleaner is finding lots of dirt in your ducts, you need to get the ducts themselves inspected to find out where the dirt is entering, and then repair the problem! (And while you're at it, take care of rodent problems.)

Yes, as a pest control operator, this is something we work with the duct cleaning services on. They clean the ducting and refer us for pest control, seal up and repairs and HVAC company for ducting repair. The issue is, this does happen, and they still need to clean those ducts when it does.

Mine were cleaned yesterday and I notice a big difference in air quality today. My ducts are intact. My we have a lot of dust here. HVAC systems are not 100% sealed, so any dust in the attic can get into your system and into your air. If you have cellulose insulation, that is dustier and it can get into your system.

I can't imagine this is a one-size-fits-all answer. I have my HVAC serviced and inspected once a year. They haven't recommended cleaning; if/when they do, I'll likely do it.

Normally, without any events occurring, preferably twice /trice a year at least... it can be very expensive and I just did all our recently-indeed, few days back.

However, since we had a lot of dust flying recently, all that collected in the machines/engines on the roof and thus they caused issues. So, we had to redo all those and clean a couple of filters too! Such a mess to clean up too sigh*

Clean what??? A good cough usually helps.

Our HVAC guy who we've used for over 30 years said to clean air-ducts CORRECTLY is very expensive. He said you're wasting money if you go with these companies that advertise for a deal. On our guy's instructions we change our filters MONTHLY. Our ducts are pretty clean. He also said those filters/systems attached to the HVAC and remove a lot of dust also reduce air-flow which could cause systems to work a little harder- so keep the big picture in mind!

We have our ducts cleaned every few years. As a dog owner you would be amazed at how much dog hair gets in to the ducts from the air vents/registers, even though the duct work itself is sealed.

If you have hairy pets or long-haired people in your house, it should be done more frequently. That's the rule for dryer vents (i.e. the hole in the house the dryer plugs into, not the lint screen), so it's probably somewhat applicable to air vents too.

I live in Houston, Texas. Our ducts are in the attic so they get hot and humid in the summer, the result of that is mold build up. I have been warmed to never turn the AC off here in the summer even if you will be gone, mold will grow in the ducts like crazy then. I see mold on the vents so I know there is mold in the ducts. We get them cleaned about 3-5 years but really should do it annually here since we have bad mold allergies. Hate to pay the price though, it isn't cheap. Most of our neighbors have allergy troubles too and get their ducts cleaned every few years or so. Last time we had many of the vent boxes (don't remember their real name) replaced, they were almost 40 years old and the AC man said the material they were lined with was something mold can grow on. The new ones supposedly are better that way. That might have been a scam, I have no idea.

Before anyone has their air ducts cleaned, please read what the EPA
says on the matter. In essence, if there isn't a specific problem
(such as mold in the ducts), you shouldn't bother doing it. If
there is a specific problem, it should be taken care off before the
cleaning process.

http://www.epa.gov/indoor-air-quality-iaq/should-you-have-air-ducts-your-home-cleaned

I placed plastic filter material in the cold air returns after having the ducts cleaned. I remove and wash this about once a year. I don't plan to have the ducts cleaned again.

Good advise markvii. We had our cleaned when the house was about 20 years old. What a waste of money. What they pulled out would not have filled a large trash basket. Lesson learned for sure.

About 20 years after moving into our new house and after a few renos (including new wood floors on the first floor and wainscoting) and the usual painting updates, my daughter (who had lived with us symptom-free for the first 10 years after we moved in) could not come to visit us without an asthma attack. It seemed worse upstairs and we thought maybe the carpet had disintegrated over time, so changed all carpeting on the second floor. No improvement. Then decided to have all the air ducts cleaned. We could hear "stuff" being sucked out of the ducts. About 12 hours after the work was completed, I was amazed to find I could sleep more easily. The head stuffiness was gone. Was it my imagination? Could it make this much difference? Then my daughter came to visit and low and behold: no asthma attack. Made a believer out of me.

If you're first moving in to a home, I'd have a full air duct cleaning done thoroughly by a pro, then every 5 years or so. With forced hot air by gas, ducts stay fairly clean - but it's the air vents/intakes in each room that require more attention. We have a simple filter attached behind each air duct in each room that we vacuum at the start of every season. Saves wear and tear on the furnace (increases efficiency), the furnace filter (which we change monthly), and keeps down the dust! Yay!

I checked never, but that's because we have hot-water radiators, thus no ducts. Had the same in our previous house and was really glad that our retirement place has the same system. Quiet and no dust.

medical studies show no benefit

medical studies show no benefit

even with a good filter system you should clean your ducting once a year. or at least once before you move into a home. have you ever seen a construction site? what about things that got spilled in there by previous owners? there is dust, pollen, mold and all sorts of things like rotting food and constricted debris in there. no matter how clean you think it is, I challenge you to call a duct cleaner, have him show you his empty bin/filter before he starts and after.

Note: the link to the EPA article given above about duct cleaning is too old (1997), very dated information. They have come a long way since then in technology.

If you have pets, if you have allergies it's helpful. We live in an area that is very humid so you can have mold spores grow in your ducts. Filters don't catch everything you can have things get in through the ducts, no HVAC system is airtight. We have ours done yearly. I can tell when it's time to do it because the house becomes more dusty.

springmom -- The link to the EPA document is current. What's presented may be old but that just means the EPA hasn't changed its opinion on the subject since the page was created. Anyway, what new technology would make EPA's opinion invalid?

Rollinggirl - duct cleaning won't remove or kill mold spores if present and I can't think of anything spores could survive on inside metal duct work anyway. As stated in my first comment way up there ^^^^......I had a main duct replaced after 32 years, 2 kids, 2 cats and a spouse who dislikes vacuuming wall to wall carpet throughout. There was so little dust in the duct when they removed it I was shocked. I should have taken a few pics but believe me, I'll never have them cleaned in my lifetime.

Mold only needs dust to survive.

Clean them directly after buying or building a new home. The amount of junk and drywall dust that migrates down the ductwork is amazing. I just cleaned mine, and although I will not argue about the quality of my air, it has not helped in creating less dust to clean up after.

You should change filters monthly, not every 3 months.

Had all the duct work cleaned when we moved in and haven't since (4 years ago). I vaccuum the floor ducts where dust and hair can collect though.

We had a new system installed about 5 yrs ago and my husband asked the owner of the company about duct cleaning because of my allergies, the owner of the company said that is a money making scam, and if homeowners would change the filters on a regular schedule and inspect the ductwork twice a year. The only time my allergies bother me is when I work out in the yard. I have listened to several people on a radio show that help people make home repairs and they have all said the same thing.

Our heating contractor cleaned ours after their work installing everything, and the dirty part of building a home, was done. They said it did not need to be done again. We have very effective filters and an ionic air cleaner in most rooms so have very little dust in our home. I don't expect much dust in the ducts either, although I do regularly vacuum the intake grates (those do get somewhat dusty) and the vent that's close to where our dog's bed is.

It is difficult to clean duct work, what I did is cut a piece of plastic sign to fit in the return register and painted both side of the plastic with the ionic paint additive in the paint. As the return air moves across the treated surface of the painted surface, the air releases anions which oxidizes ant toxins or odors in the duct system. Picture attached. Vance www.ionicpaint.com

I've never had ducts cleaned, however, I intend to do so once renovations are done on our home. I discovered throughout the years that many of the tradesmen and construction workers throw drywall pieces, tile and misc debris in vents. I have vacuumed out what I could, but suspect there are many more items lurking in the vents.

filter are useful and do their job from the furnace to the registers but there are usually no filters from the air returns to the furnace and that's the part the should be cleaned every couple of years more so than the supply ducts

I once lived in a home built in the 70s that got a dead mouse in a duct. We had those ducts cleaned. I think that's the only time I've had that done but I'd get it done if I moved into a house with dubious pre-existing HVAC (like someone obviously not using filters properly, etc.). Otherwise nah. We change our filters about every other month because we have pets so they get furry and dusty.

One day last fall, I noticed that the bedrooms end of my house was not getting any heat.

A handyman I found on our local Nextdoor website offered to come over and take a look before I went to the expense of hiring a furnace repairman.

It turned out that a large stray cat had been camping out on a duct joint and had managed to disconnect the duct altogether! The handyman reconnected the ductwork securely -- and re-screened the vent hole where the cat had been getting in. Bill: $80 total for parts & labor!

I've never had an HVAC professional recommend doing that. There are obviously reasons to do so, but generally no.

I become very sick from mold, and therefore my body can detect it in even small quantities. I can tell you that many, many homes and buildings have mold in their ducts. Here is why. In the past we built ducts from metal. Insulation was placed outside the metal ducts. That was fine. But now we have switched to flexible ducting which tears easily so the insulation is exposed. This absorbs any moisture which goes through the duct; of course organics also go into the duct and are trapped, and now you have a perfect petri dish for mold growth. These ducts also are impossible to clean. They are not smooth and they tear easily.

Many people believe that there is no mold in dry climates. In fact I find the opposite. People tend to put humidifiers on their HVAC systems in dry climates, and that makes the problem even worse. Also air conditioners create a lot of moisture, and homes with AC are often problematic.

Bi-monthly, along with my filter... gives my A/C unit a longer life

Well, I remember when there was some problem with Air conditioning cleaning; I used a cleaning machine & tool for this by FIFTY REASONS for which I found the excellent service in cleaning air ducts. So I need rare air conditioning maintenance & I must say proper AC maintenance is needed.

Another vote for ductless mini-splits!

I cut down filters to put behind my air intake grates, and man, those things get disgusting after a month or two. And I change the furnace filter monthly. And every few years have the ductwork cleaned. Is my air cleaner or will my furnace last longer? No idea but it makes me feel better so it’s worth it.

There's not good evidence that it helps with allergies...why waste the time, effort or money?

We have two pets and five adults in our happy Home. We change our furnace filter every month. (It is a 3 month filter) and try to clean the duct every 6 months if not every year. We live in Oregon (wet side) and in a 70's ranch style home. It is large and there is some dampness. We also have one smoker .

We have a new heating system with the space system filter and much more preferred the blue light.

It was so clean you could see it in the air..

Hope this helps.