Hocus Pokus and mis-direction
So, you would like to hire a Duct Cleaning service, The trouble is that you don't really know what is to be expected of a
service. Duct Cleaning is different from most other services you will ever purchase. When you have your carpets
cleaned, you can see the work being done and the carpets will be brighter and even a little damp. If you buy a meal
you get food on your plate and if you pay for gasoline your fuel gauge goes up. But what about a Duct Cleaning? All of
the spaces to be cleaned are internal and mostly out of sight. So how will you be able to know if anything at all is
being cleaned? And if you can't see what's going on during the procedure, how exactly then can the technician
performing the work know if they cleaned anything either? The not so surprising answer is, they can't.
So what's going on?
Much like buying a hammer, doesn't make you a carpenter, purchasing some equipment without any knowledge of
how to use it, doesn't make a Duct Cleaning Service. The easiest thing to do is to first show you how a reverse air
duct cleaning from Duct Boss works properly, from inside-out, and takes the guess work out all together, while
protecting HVAC equipment from harm. Next, I will show you everything that is backward with the industry standard. I
will provide a list of meaningful questions which you use to compare with other services.
The Mysteries of Duct Cleaning Revealed
Nearly every service you will come across is actually unaware of how to operate their own equipment, and
are working from outside-in and backwards. In every case, this will create a worse situation than when
they arrived, and may damage your equipment.
Reverse Duct Cleaning Explained
Looking at Diagram 1,on the diagram page, you will see a representation of a standard Duct system. There are as
many different configurations as there are homes, but this shows the major components.
All duct cleaning is actually in two very different stages
Top End Cleaning
The first part to Duct cleaning is the living space, which is connected to the air handler through a series of branch
lines, see figure 1. In most cases these lines are fed in to larger main lines.
The idea is to remove the debris with in these lines, starting from their furthest point (IN), where they connect to the
mains, moving the debris away from the system (OUT). This is done with flexible high pressure lines which have
reverse air agitation devices attached to them. The arrows in diagram 1 show the direction of air flow, and debris,
moving away from HVAC equipment. When the debris is removed it is gone from the system as opposed to being
pushed further in. Attached to the vent openings are custom built caps where a HEPA VAC. is installed to capture
loosened debris. The "caps" all have a window installed. This means the operator can see when another pass with
the equipment is necessary and when it's okay to move on. I frequently remove toys and ping pong balls,
candies,pieces of old dry wall, bugs,dirt and all manor of junk. All of which would be forced, unseen, in to a
concentrated pile, deeper in and most likely stay in the system forever,if the air flow moved toward the lower part of
the system. Further more, working blindly, the operator would not know what was happening or when to move to the
All supply and returns will be cleaned this way. They can be done at the same time which eliminates the need to go
through every room twice as is needed when relying on a backward set up negative air system which has to hook up
first in either the supply main and then in to the other side to finish the top end. It is also not a problem to leave the
air conditioning or heat on with a reverse air cleaning system through out a top end cleaning, so the house will not
become uncomfortable during the several hours it can take to complete a top end cleaning.
LOWER END CLEANING
The lower end cleaning involves entirely different equipment and practices. If your system has just two main lines it
should be possible to clean the lower end in the same visit. Some systems have a web of up to a dozen sections
which require multiple repositioning of the negative air as well as many clean out holes to be cut and patched, aside
from actually cleaning out each section as well. Looking again at diagram 1, you will see how a negative air line
which comes in from the equipment truck, is hooked up to the main lines. In this example the air handler( furnace) is
positioned in between the two ends of a supply main. The negative air is hooked up, one spot at a time, on either
end or at least an acceptable distance from the HVAC equipment.. Large clean out holes are cut on either side of the
air handler. In this way, debris can be directed away from the HVAC equipment. If the positions were reversed then
debris which was not caught by the vac air stream might fall in to the air handler and coat the AC coils. The access
holes are large for two reasons. The correct air lines used in the lower end are a set of semi flexible rods. The
access hole must be large so the operator can place a hand up in side to guide the tool. The tool will actually fit
through only a one inch hole and if you watched another service doing this it may look like all is going well. What
would actually be happening out of sight is the rods would be entering at maybe a 30% angle and would have to
advance about eight feet before gravity would bring the end down to the floor level where the debris is mostly laying.
An entire section would be missed although this would go unseen as other services work blindly with only a tiny one
inch hole. So that's the other reason for the larger more time and material consuming holes to be cut. It will allow the
use of lights and a periscope or camera, and actually moving the rod system around to clean,so each length can be
confirmed clean before moving on.
Industry Standard Method Explained (Backward and Blind)
So, now let's take a look at diagram 2. This is the method used by nearly all other duct services. As the diagram
shows, the negative air hose will be attached as close as possible to the air handler(2), and will be turned on during
the top end cleaning. Flexible air lines will be inserted in to the openings of either the supply vents or the returns,
depending on which side the negative air was hooked up to first. Working backward, the operator will actually begin
to force debris down further in to the system. Where the debris is going is impossible to say, except that for certain it
has not been removed. The reason we can't know is of course because no one can see down a twenty foot tube.
The operator is working on a misconception, while working blind, that their air hose is so powerful, that if there was
any dirt in there, it certainly must have been pushed in to the main line below. This is what they are taught to say to
any customer smart enough to be concerned. I would love to tell you that our tools go all the way through each
branch line with never a snag, but it just isn't so. These lines can be made of metal and have dampers that get in the
way or poorly connected joints which catch the tools and may also have sharp bends which can not be negotiated or
be made of flex pipe which has ridges which a tool can become stuck on and preventing the tool from sliding
forward. This happens all the time. All we can do is the best we can do and get as far a particular branch design will
allow. So what happens when their air line encounters one of these situations? First the operator will remove the
tool as nothing happened and move to the next vent, knowing the customer has no idea how far the tool went in,
weather they were watching or not. What happened out of sight is that any debris which was being moved, is now
forever in and concentrated, out of sight and reach of any further cleaning methods, deep in to the branch line. They
will then move the negative air hose to the other side and go back through your entire home again with the same
IT GETS WORSE
Now the operator will be moving to the lower end. The idea here is that some of the dirt they moved from the branch
lines may have made it in to the main (1). What they want to believe, or want you to believe, is that they can place a
tool at the far end through a one inch hole, and blow the contents of the main in to the vacuum air stream
There are so many problems with this I don't know where to begin
Some mains have a layer of internal insulation like a carpet. Dirt and debris stick to this like pet hair on clothing. It is
nearly impossible to clean well, and any extra debris that got pushed in to it is going to stay there forever. Just like
with the upper section it will not be any trouble for the technician. They will quickly go through the motions. Neither
they nor you can see anything any way.
Next they are going to insert the clean out tool from the far end through a one inch hole ( 3 ). The semi rigid rod
system will go in to the main at about a 30% angle and ride along the top of the main until gravity brings it
downward. It will miss about eight feet of floor which is where the dirt is mostly laying. Like a magician's act it would
look fine from the out side. The rods are being pushed in and there is a lot of noise.
When the air rods do get up to the vacuum hose, some loose dirt may be forced past the vacuum and fall in to the air
handler located just a foot or so behind the vacuum. Next, any dirt located after the vacuum will certainly fall in to the
Next, they drill another one inch hole on the opposite side. If they push dirt from that side and attempt to "bridge" the
air handler they will certainly drop all of that dirt in to it as well before it could reach the vacuum air stream.
There are several other types of main lines the proper procedures will not be known or followed for these either.
They simply have one method and it all depends on uneducated customers not knowing what they are seeing.
It is not unusual for the same flexible air lines from the top end to be used in the lower portion. These lines are
incorrect and just curl up in side the mains and again it might look from the outside that they are going in and down
through the main. As I said there are so many problems that I really can't hit on them all.
Go to Q and A Page
Typically a Company will prefer to quickly explain their service using simple phrases such as, "we have the most up to
date equipment" Or "our highly trained technicians"... You will need real information to make a good decision.
Thanks again for your time.
Owner / Operator
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Residential Air Duct Cleaning Service
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