It’s a fair question. It stands to reason that using powerful equipment to blow and suck dirt in order to move it from inside your ducts to an industrial containment off-site might result in some residual debris or airborne dust in your house. But how much is acceptable, and how much is normal? A good tech from a reputable company should do everything they can to minimize this nuisance

Preliminary precautions to keep your home clean

The first thing any tech should do when entering your home is either remove their shoes or place booties over them to prevent depositing onto your floor whatever was on their soles. They’ll also likely lay down tarps to protect your flooring from the large vacuum hose that will run from their truck down to your furnace (unless they’re using portable equipment). Some technicians will up the meticulousness factor further by placing corner guards to protect wall corners from any potential damage. 

In order to position the vacuum hose in your main trunk line, they’ll need to cut access into it, and for this task they’ll probably use tin snips. To prevent those tiny metal shavings from falling onto your floor (ouch!), there are products, such as Chipmaster, that collect the shards before they fall. Any technician not taking this simple precaution should cleanly sweep them up. 

Another precaution they may take, depending on how large your home is and what level of cleaning you’ve selected, is to cover the vents with adhesive or magnetic vent covers. These aid in keeping the dust level down when each of the other vents are being serviced with the cleaning tools. The covers can also help to create extra suction power. On a smaller system (under 2500 sq ft), they may not be needed and in fact may be counterproductive because of the sheer force of the vacuum.

During the service

Most air duct cleanings work by utilizing the power of negative pressure. An industrial-strength vacuum is hooked into the trunk line near the furnace. Then, with the system under negative pressure, the technician services each vent, room by room, with various tools designed to move debris from the branch lines to the trunk, where it's captured by the vacuum.

This negative pressure is the key component to minimizing the blow-back of debris into the house: all of the force or pressure exerted by the tools is directed toward the vacuum, increasing the negative air flow. Any vent covers placed over the registers will help in this process, both by creating more suction and by preventing debris from exiting the vents that aren't being serviced. 

In some cases, especially when the vents are particularly dirty, a small amount of dust from the corner of the vent will go airborne briefly in a small poof when the tool is initially engaged, usually being quickly sucked back into the system shortly thereafter.

When things go wrong

Things don't always go according to plan, of course, and sometimes despite the best intentions more dust than we'd like escapes the system and enters the living space. There are a few scenarios under which this could happen. 

In some cases when additions are constructed onto houses or retrofitting has been carried out, new vents are installed too close to the existing ones, or two vents are installed on the same branch. This unconventional installation is one of the most common reasons for dust exiting the vents during a cleaning. 

Excessive dust can also occur when a basic duct cleaning is performed on a system that begs for a higher-level cleaning, since large volumes of dust are present and being agitated but the tools used are insufficient to handle it all. Sometimes budget-conscious customers opt for a lower level of cleaning than needed, reasoning that a basic cleaning is better than none at all. It is arguably better to simply wait until the appropriate level of cleaning can be purchased. 

Finally, a cheap, ill-fitting, or bent furnace filter could easily allow dust to bypass the filter during the cleaning of the returns, causing dust to enter the supply line and escape from the supply vents. When this occurs, it is usually quickly apparent to anyone in the house, and a diligent technician will specifically check for these things before beginning the cleaning. 

In the event any of these problems occur, the technician should immediately halt work, investigate, correct the problem, and finally—clean up.

After the fact

With the proper precautions, many on the part of the tech but some (like air filter issues) on the part of the homeowner, excessive dust entering the home during routine air duct cleaning can easily be avoided. Small amounts of residual dust are normal and difficult to avoid, but large amounts of airborne debris settling onto furniture and into the carpet are not. 

A diligent technician will not only take precautions to prevent the accumulation of debris inside the home but will also perform any cleanup necessary. A diligent homeowner will inform the technician if they are unsatisfied with any aspect of the job, including residual debris. The cleaning company will want to be made aware of these occurrences as well, so that they can ensure technicians receive proper or additional training in this regard, and so that they can ensure the homeowner is satisfied with the final outcome.

Wanna dig deeper? Download our free tipsheet: 10 Questions to Ask Before Hiring an Air Duct Cleaning Company. 

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Many thanks to our technicians Ben S and Roy S for lending their expertise to this article. 

On the latter question, that depends, says Carolynn Carleton, a real estate agent with Coldwell Banker Burnet in Minneapolis. "Right now, it's a seller's market, so it's more difficult getting sellers to accommodate demands or conditions on the part of the buyer, since they can simply take the next offer." If it's a buyers market, on the other hand, the buyer can more easily set performance of a service as a condition of purchase. "Every transaction is unique."

Whoever pays for HVAC cleaning services, there are several that should be considered in order to ensure a smooth transaction, and to ensure the cleanliness and proper function of the various systems for the incoming party. 

Air Duct Cleaning

The average person having any awareness of the detritus that lurks inside air ducts would choose to have them cleaned when taking ownership of a new property. Besides the usual gross accumulation inside, such as pet fur and dander, crumbs, and household dust, our technicians find all manner of strange items in ducts. Anything that can be dropped down a vent (or in many cases deliberately placed there) can be found within. It's wise, and common, for new homeowners to either request this service of the seller or do it themselves on move-in. 
In our experience, air duct cleaning may best be left to the buyer on move-in. Our office has handled many calls from sellers looking to have their ducts cleaned either because they are getting ready to list their home and want to increase its attractiveness to a prospective buyer, or they already have a buyer and said buyer has made air duct cleaning a condition of purchase. Unfortunately, sellers on their way out often choose the lowest tier of service, which may or may not suffice for the condition of their ducts—particularly if it's been a long time since they've been cleaned. 

Besides being potentially unfair to the buyer, this choice could complicate matters for both buyer and seller at closing. We've observed on occasion that after a maintenance-level duct cleaning was ordered by the seller—believed sufficient to fulfill their obligation--an inspector on final walk-through determined the air ducts to be insufficiently clean, thus delaying the closing. This is a situation no one wants to find themselves in. 

Carolynn, with Coldwell Banker Burnet, represented a buyer a few years ago who was highly allergic to cats. When this client set her sights on a house whose occupants owned several, they decided to amend the purchase agreement with a stipulation that the sellers have the air ducts and carpet cleaned prior to purchase. The sellers did so and then provided the receipt to the title company prior to closing so everything would be in order. The closing went off without a hitch, but as a precaution, considering her client's allergies and the ubiquity of pet dander, Carolynn recommended her client have the process repeated on move-in, ensuring her environment was as free of allergens as it could be.   

Dryer vent cleaning

Because dryer vent cleaning is critical to home fire safety, it's an HVAC cleaning task that should be performed regularly. The seller should be asked when this service was last performed, and if not within the past year, the buyer should see to it shortly after move-in (if not prior to purchase). 

Examination of the dryer exhaust system falls well within the purview of home inspection and thus this system will be looked at by the buyer's inspector. They will check, among other things, that the vent line terminates outside the home, that the correct type of venting material is used, and that there is no screening over the exhaust termination (which could trap lint).
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Often, however, in the course of cleaning out a dryer vent line, technicians discover hidden irregularities (behind a wall, for example) that were missed during inspection and that could cause significant damage if left unaddressed. In the photo below, for example, we observed a dryer vent that had been exhausting into a floor/ceiling cavity because of a disconnect in the vent line. (Because the visible parts of the vent line were secure—including that from the dryer into the wall behind the machine, and that seen from the exhaust vent outside the house--everything appeared to be normal.) Judging by the amount of lint observed, this condition was present for a couple years before its discovery by our technician, shortly after purchase of the home. 

Because HVAC cleaning technicians usually focus on one or two systems during a service rather than the house as a whole, they can sometimes have an advantage over inspectors in discovering defects in a system. In the case of dryer vents, in the process of cleaning the vent line the technician must check for good air flow from the outside exhaust as part of making a determination that the line is clean and clear. When a disconnect is present, air flow from the outside vent will not be achieved, thus prompting the technician to investigate and troubleshoot.  

Chimney sweeping

No one wants to move into a home with a dirty chimney or fireplace. But even less desirable than unsightly debris in the firebox is the danger of creosote buildup on the inner walls of the chimney. Creosote forms as the byproduct of wood burning. It builds up inside the chimney over time, inhibiting draft, and, in sufficient quantities, creating a fire hazard. A thorough chimney sweep is definitely in order before use of the fireplace by new homeowners. 
While it's important to remove blockages and buildup from the chimney, just as critical is having its structural integrity evaluated in the form of an inspection. Many chimney sweeps offer Level 1 inspections free with a chimney sweeping service, but the CSIA (Chimney Safety Institute of America) recommends a Level 2 inspection on the sale or transfer of a property. This advanced level of inspection will include a video scan of the interior surfaces of the chimney, to look for cracks in the liner or flue tiles and other deficiencies.  

The condition of a listed home's chimney will usually be referenced in either the Agent Remarks or the Public Remarks on the MLS listing ("chimney is functional," "chimney needs to be checked," etc) so that the buyer can make a determination as to whether its condition or how thoroughly it's been checked is acceptable to them.

Carolynn, our Minneapolis-based realtor, said that many listing agents will have the chimney checked out before the property is even listed, particularly if it hasn't been used in a long time, in order to avoid any potential liability. She generally recommends that her sellers have an inspection performed so the chimney can be deemed safe, since this can serve as a huge incentive for buyers—and by extension a huge disincentive if it hasn't been done. Many buyers will not even consider a property whose chimney has not been checked, and they themselves do not want to undertake the cost of doing so—or worse, risk purchasing the home only to find out on move-in that the chimney is in a state of disrepair. Chimney repair jobs routinely run into the thousands of dollars. 

Ultimately it's up to the buyer and seller and their representatives to hash out which services are appropriate and when, as well as who will cover the cost. With all parties entering the negotiations well-informed and in good faith, the end result should be a smooth transfer of property and a safe and welcoming home environment.

Wanna dig deeper? Explore our HVAC cleaning service pages, including a detailed description of the cleaning process and tools utilized for each system.

 View HVAC Cleaning Services
 
Many thanks to our technician Roy S. for lending his expertise to this article.

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Dryer vent cleaning is usually a pretty routine event: the technician inserts a tool through the vent line from the outside and feeds it through to the back of the dryer, then pulls the tool out, extracting the lint with it. But every once in a while our technicians encounter a particular job that is not so easy, or so routine.

The symptoms

In March 2019 a homeowner in Maple Grove contacted us for a routine dryer vent cleaning. His dryer was not working efficiently and was taking much longer than usual to dry clothes. This is a frequent symptom of a clogged dryer vent, so our technician did not expect to find anything out of the ordinary. The dryer vent exhausted out the second floor of the home, about 15 feet up, making the total vent line about 30 feet in length. Longer vent lines often harbor more lint than shorter ones—for example, those that vent straight out the back wall.

The first order of business for our tech on this job, as with any dryer vent cleaning, was to vacuum the machine's lint trap compartment with a crevice-tool vacuum attachment. This step removes any debris that sneaked past the lint trap. He then eyeballed the back of the dryer to ensure all of the connections were secure. With those two tasks complete, he ascended the ladder 15 feet up to the outside vent.

The diagnosis

Having turned the machine on "air dry" before leaving the laundry room, the technician expected to observe at least some air flow exiting the outside vent, but there was none at all. For this reason he assumed he was dealing with a 100% blockage in the form of a dryer vent clog. This is the number one reason for restricted air flow through a dryer vent line.

His tool of choice is a reverse-blowing spinning skipper ball attached to the end of an air snake. This he feeds into the vent line through the outside vent, where warm air (and some lint) typically exhausts. He expected to meet some resistance in the form of a clog, but he soon heard the skipper ball reach the back of the dryer, at which point he realized his first assumption may have been incorrect. On pulling the tool back toward him, a good deal of lint was expelled, but not as much as expected for a clog capable of completely restricting air flow. He inserted and retracted the tool several times until he was confident all of the lint was removed from the vent line. 

Now certain that the issue was not a clogged vent line, he proceeded downstairs and had a closer look at the machine itself. Pulling the machine away from the wall, he noticed there was an exceptional amount of lint behind it. He further noticed that the portion of the vent line that normally extends from the back of the dryer across the bottom of the unit and connects to the fan was disconnected, sitting idle and useless in the bottom of the machine, enveloped in a gray cloud of combustible lint.

The solution

This particular dryer vent disconnect was unusual in that everything appeared, from the outside, to be appropriately connected. Additionally, the location of the disconnect, inside the dryer itself, is relatively rare; often disconnects occur further down the vent line, sometimes behind wall cavities or inside the attic.

Disconnects in the dryer itself pose a particular danger in that instead of lint building up down the vent line, removed from the machine and its heating element, in this case it builds up inside the dryer itself. Lint is highly combustible and easily airborne, so one can imagine how its blowing around inside the dryer near the heating element would be extremely problematic. 

The first thing the technician set about doing was cleaning out all of the lint from inside the dryer, with an industrial vacuum. The photo above was taken when that process was nearly complete. Once the lint was thoroughly removed, he easily reconnected the missing portion of the vent line, confident that after doing so, excellent air flow would be established.
He was correct.

The lesson

Having your dryer vent regularly cleared of lint and any blockages serves several purposes, primary of which is to minimize the fire hazard created by a buildup of lint. Doing so also improves the machine's efficiency, by increasing the air flow necessary for it to do its job.
But the often overlooked or unanticipated benefit of dryer vent cleaning is the discovery of these vent line disconnects, which typically occur in places where they can't be seen. Left unaddressed, they wreak havoc inside the home, exhausting warm, moist air into spaces where it surely doesn't belong.

Once corrected, the vent line exhausts fully outside, where the warm air, moisture, and bits of lint quickly disperse and harm nothing, as intended.

Wanna dig deeper? Download our free tipsheet: 5 Questions to Ask Before Hiring a Dryer Vent Cleaning Company.  

Download Tipsheet
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Many thanks to our technicians Ben S and Roy S for lending their expertise to this article.

Your HVAC system relies on good air flow to work its magic: heating, cooling, and ventilating your home. When your furnace is choked with dirt, your flue blocked with animal nesting, or your dryer vent clogged with lint, these systems are hindered. At best the associated system loses efficiency, at worst you risk a house fire or the backup of toxic gases into your home

Let's take a look at how proper air flow affects the smooth functioning of each of the HVAC (Heating, Ventilation, and Air Conditioning) systems. We'll include the dryer venting system here, though not strictly considered part of the HVAC system. (It does feature a vent, after all, and serves to exhaust heated air outdoors.)

Air flow creates draft in your chimney

Your chimney relies on the process of draft to maintain combustion and to safely vent its byproducts from your home. This includes not only your fireplace flue but your furnace, water heater, and boiler flues as well. Via the process of draft, warm air and the smoke or gases it carries from the source of combustion, moves up through the flue and is exhausted outside the house, often onto the roof. Any kind of blockage or other hindrance will impede air flow and prevent draft. 

Without draft, of course, the necessary sequence of events will not unfold, at which point back-drafting can occur. In the case of a fireplace chimney, this will result in smoke coming back into the home rather than exiting the chimney. In the case of a utility flue (furnace, etc.), this will result in toxic gases, such as carbon monoxide, backing up dangerously into your living space. 

Air flow carries warm air and lint away from your dryer

As your clothes dryer spins and fluffs and dries, the hot air generated by the machine is pushed out the back of the unit and through the dryer vent line, where it safely exhausts outside. Over time, as tiny bits of lint are deposited within the vent line, air flow slowly becomes restricted. Restricted air flow begets restricted air flow; that is, the more lint that is deposited, the more air flow is restricted, in turn leading to more buildup, until air flow is choked off completely by a dryer vent clog. 

Once a dryer vent clog has formed and air does not flow freely, several things can happen. The best-case scenario is that your dryer's efficiency is reduced and takes longer to dry clothes, or it simply shuts down. The worst-case scenario is that the heat, having no escape, builds up inside the vent line and ignites the lint, causing a fire. For this reason, no dryer vent cleaning job is considered complete until good air flow has been observed from the outside exhaust vent.

Air flow through the air conditioner's A-coil transfers heat

Your A-coil, or evaporator coil, is one of the indoor components of your air conditioning system. Its function, by way of a series of refrigerant-filled tubes, is to absorb heat, thus cooling your indoor air in the summer. The exterior of the A-coil consists of a series of small, tightly spaced fins that help this process. Because these fins usher air toward the coil, when they are dirty or clogged the entire process is interrupted. 

But the ill effects of poor air flow through the A-coil are not limited to your air conditioning system. Because all air that circulates through the HVAC system passes through the A-coil—whether it is your furnace or the AC that's running—a clogged evaporator coil has the potential to hamper not only the cooling of your home but its heating as well, and to drive up utility bills. Dirty components equal restricted air flow equals reduced efficiency equals higher energy costs. You get the picture. 

Air flow through the furnace generates heat

Your furnace's job is to pull air from the return air ducts, warm it, and push the warmed air out through the supply ducts into your living space. Proper air flow is of course critical to this process, from beginning to end and back around again. Here are some points at which it is especially vital.

• A gas furnace's "sequence of events" dictates that there must be sufficient draft detected in the furnace flue by the pressure switch in order to trigger the hot surface igniter, initiating the heating process. Inadequate air flow will stop this process in its tracks.
• The blower pulls air through the filter before it enters the furnace. When your air filter is clogged, air flow is reduced and the blower must work harder to compensate for the diminished flow. 
• The heat exchanger relies on proper air flow to keep it from overheating, so a decrease in air flow from the blower will not only cause the blower motor to work harder but could cause the heat exchanger to overheat and fail. 
• Diminished air flow through the evaporator coil can be extremely detrimental to the system's functioning, causing an insufficient amount of air to move from the heat exchanger to the supply duct and potentially creating a backdraft. 
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In short, each individual component of the furnace or air handler can potentially interrupt the system if it is not receiving or detecting adequate air flow. 

Maintain proper air flow with HVAC system cleaning

If you've read this far you probably don't need convincing that proper air flow is critical to the smooth functioning of your HVAC system. Any hindrance to adequate air flow in the form of dirt or debris can create havoc and lead to equipment breakdowns. 

HVAC cleaning calls into action an arsenal of specialized tools (rotary brushes, air snakes, tentacled air whips, high-pressured air triggers, industrial vacuums) and technician expertise to rid the system of component-clogging dirt and debris. The result is a system that functions more smoothly and efficiently, performing its task in less time and using less energy to do so. 
Just as our lungs and respiratory systems need unobstructed, smooth intake and exhalation of air to function as they should, so must our HVAC systems be able to "breathe" freely in order to do their best work for us.

Wanna dig deeper? Explore our HVAC cleaning service pages, including a detailed description of the cleaning process and tools utilized for each system.

 View HVAC Cleaning Services
 
Many thanks to our technician Roy S. for lending his expertise to this article.
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