Article In NADCA's Duct's Tales publications

Technology focus
What technology to use?
Robotics - Compressed Air Nozzles – Brush Systems?

Since the beginning of the 1990’s the debate and discussion between manufacturers and contractors on what type of technology to use and which one is best suited to clean ventilation systems has been a never-ending story.  It is very difficult to answer that question due to the fact that HVAC systems are designed in various ways and each type of technology have their own advantage in certain applications.  If you are to decide what type of technology to purchase, you have to sit down and figure out the following

To answer these questions is important in order to know where your company will be five years from now.  It is also important to know these answers when you decide what type of technology you are to invest in.

Duct-work design.
The design of ventilation systems will always be a problem for duct cleaners due to the fact that the ideal duct-work does not exist. 

What you see on Trade Show and Exhibition demonstrations is in most cases a section of the ductwork that is exposed in the most favorable way.

Obstructions and size/shape changes.
Duct-work under realistic conditions, contains many obstructions & changes of size and shape.  In most cases you will find obstructions inside the duct-work such as, turning vanes, splitter dampers, sensors, air-deflectors, VAV boxes, heating/cooling coils and volume dampers etc. that will effectively limit the use of robots and brush systems. The small air-nozzles will however easily be able to pass through these obstructions in most cases without problem. 

The changes of size and shape of the duct-work creates problems for robot and brush systems. When the duct-work change shape or size from 3ft to 10” (or vice versa) the brush/robot operator must do the following: 

 Insulated, Fiberboard or Flex ducts.
Ductwork cleaning is all about effective and complete surface agitation, which in insulated fiberboard ductwork can be a problem. Both brushes, robots and air nozzles can easily “tear up” the insulation, fiberboard or the flex ducts during the cleaning process.  However, new designs of the 75-100 Cfm Air Knife Nozzles have been able to eliminate most of these “tear up” problems during the cleaning process.  The addition of special developed and designed anti-microbial coating features via these nozzles take care of sealing the insulation and fiber board after the cleaning phase are completed. 

It is in most cases less expensive to replace flex ducts compared to cleaning.  The removal and replacement procedure allows the operator to get access to the duct-work, which eliminates the need of cutting numerous access holes.  This saves money for labor and the cost of multiple access doors. 

Vertical Risers and branches.
Anyone using common sense will understand the problem robots will experience when vertical risers are to be cleaned.  In most cases it will be very difficult to use robots! Also branches that usually are designed at a 90 degree angle from the main duct-work, in addition 3-4” above the bottom of the main duct and finally in most cases with a totally different size and shape, make the use of robots almost impossible. Are these conditions something a duct cleaner rarely finds?  Absolutely not, this type of conditions exists in 95% of all duct-work installed.

Re-contamination problems.
The best method to avoid re-contamination of the facilities to be cleaned is to use a method that sets the ventilation system under negative pressure during the cleaning phase.  This is commonly used by brush, robot, and air whips, skipper balls and compressed air knife methods. 

However, every time you remove the cleaning tool from the duct-work in order to move the tool to a new access hole or part of the duct work, you have a possible risk of contaminating the surrounding area. 

When using small air nozzles and air knife nozzles the risk of contamination is minimal compared to brushes and robot systems.  The reason is simply that the brushes and the robots are covered with the dust and debris, which they are supposed to clean out.  This debris will eventually be released to the surrounding areas while moving and inserting them to the new access hole.  Also the need for many access holes by robots and brushes multiply the likelihood of contaminating the air. 

“Don’t forget that your customer wants you to clean and disinfect his ventilation system, not to move the problem from the duct-work into the working or living areas”.

Sanitizing & coating/Painting
In some cases sanitizing and (or) coating/painting the inside of the duct-work is necessary.  Different types of EPA Registered sanitizing fluids and anti-microbial coating materials are available on the market today.

The methods to insert these chemicals into the duct-work is however different.

I believe that most experts agree on the method to sanitize the duct-work from the inside, is the one to recommend.  

Quality of work performed
The quality of work performed is depending on several factors, including:

The most important factor is an experienced project manager, also factors as education and NADCA Certification of the operators will determine the quality of the work performed. The best equipment in the world can not help a project manager or operator, who has no other intention then to make a “quick buck” on the job.  The equipment factor is only measurable when used by quality minded contractors and their operators.  In general the different compressed air nozzles are superior compared with brushes and robots (as earlier described) and for reasons, such as the fact that they reach all areas of the duct surface (including corners) where brushes and robots are unable to clean.  But whatever type of technology you will use, there will always be areas of the ventilation system that must be cleaned by hand. And again, the quality thinking of the contractor and his operators are the real key to obtain a high quality standard and end result.

Video inspection of ductwork
Robot Systems are probably the most effective way to inspect the inside of duct-work.  Although the robot method is very time consuming, the detailed result and ability to zoom in desired spots and areas of the duct-work are excellent.

Remote Video Inspection System that are mounted on flexible rod’s with internal cable is however an acceptable solution.  The time to inspect the duct-work is greatly reduced due to the flexibility of this type of systems.  The quality of the video screen pictures as well as the video tapes is very sharp and detailed in order to get evidence on the conditions of the duct-work.  A very important factor is of course also that the cost for a robot inspection system normally is approximately ten times higher than a conventional Video Inspection System using flexible rod with internal cable.

What type of customer?

Customer
The types of equipment you need to service different types of customers are of course not the same for a residential customer as for an industrial or commercial customer.

 Residential.
To service the residential market your type of technology will be basically as follows:

Limited effectiveness!

Comments:  The time savings in set-up time and cleaning time when using compressed air compared to robots or brushes are in most cases overwhelming.  The reason is that residential duct-work is small in size and the access to the duct-work is usually via the basement and registers in the living areas.  

To cut big access holes to be able to access the duct-work when using robots or brushes takes time.  Also to get the robot or the brush from the basement to the 1^st and 2^nd floor (without cutting additional access holes) is almost impossible. 

Light Commercial
The light commercial market opens up a limited use of brushes and robot system in addition to Air Whips, Skipper balls and high volume Air Knife Nozzles.  You need to invest in a bigger dust collector (vacuum) in order to maintain the negative pressure in the somewhat bigger duct-work.

To service the light commercial market your type of technology will be basically as follows:

Comments:  You need more experienced project managers with the ability to read complex blue prints and having good planning skills.

 Commercial/Industrial
When you enter this field of IAQ remediation the need for experienced professional individuals become critical.  The same thing becomes important when choosing type of equipment.  Due to the size and complexity of the duct-work, all types of low airflow technology become impossible to use. The only air pressured technology that is able to tackle this type of vent systems is the high pressured air knife systems. 

 Robots and brush systems can in most cases not handle the diameter and size of this type of duct-work.  

 The high airflow air knife nozzles has for almost 10 years been proven to handle all types of commercial and industrial ventilation systems. This technology has also been able to clean high tech systems used in “dust free” environments like the computer industry (chips and semi conductor plants) also the highly complicated Medical and Pharmaceutical industry has been successfully cleaned by the high pressure air knife technology.  

 The reason is of course the flexibility, power and “clean operations” that this technology uses during the cleaning process.  Also factors like the sanitizing & coating features make this type of technology preferable when cleaning this type of duct-work and complex ventilation systems.

 To service the commercial/industrial market your equipment needs will be different from time to time, depending on what kind of facility you are to clean. 

 Comments:  You will need well educated HVAC engineers and project managers with excellent management skills to handle this type of projects.  

 Special equipment
When cleaning special projects that involves proven or suspected contamination of viruses, bacteria or other harmful contaminants it is recommended to use more effective filtration devices together with the dust collectors (vacuums).  During this type of operations a normal HEPA Filter (99,97% at .3 micron) is not enough.  It is recommended that you use anti-microbial treated (VLSI graded) ULPA filters (99,9995% at .12 micron).  These filters capture particles such as viruses and bacteria in the size range between .3 and .12 micron. 

Even using HEPA grade filtration will risk the spreading of diseases, viruses and bacteria throughout the facility you are cleaning. 

The only other method to avoid contamination under this type of circumstances is to set up all dust collectors (vacuums) outside the facility in a non-accessible and secured area, similar to procedures used in asbestos remediation.

Conclusion
My input in this debate is based on more then 10 years of experience from the after-fire restoration and ventilation cleaning market on a global basis.  It is also based on feed back from our licensees in 25 countries who on an ongoing basis contribute their experience from the field and keep me updated on new developments in the IAQ Field. 

It is up to everyone to make his own decision on what he wants to accomplish with his IAQ business and what type of equipment he is going to use.  There are several good products available on the market as well as several “bad” products out there. 

My advice is to sit down and analyze your company, who your current customers are and who your customer will be in the future.  Also think about what kind of services you intend to provide the market in the future. Are you willing to be a part of a franchise or licensing network, or are you a “lone warrior”? This analysis of your business and were you want to end up will make it easier to make the right decision on how to move forward. 

And don’t forget that the best decisions are usually the ones you make by “gut feeling” and by using “common sense”.

Goran B. Andersson
President of Collom Enterprises Inc. a manufacturer and distributor of a wide range of patented duct cleaning equipment, based out of Buffalo, New York. USA