QUESTIONS

1. What is air duct cleaning?

Air duct cleaning is more than cleaning air ducts. A more appropriate term to use would be "HVAC system cleaning." The system includes everything in the air stream like all of the registers, grilles and diffusers, the supply ductwork, and the return ductwork. In residential systems it also includes the furnace or air handler. In commercial systems it would also include turning vanes, reheat coils, variable air volume boxes, dampers, etc.

Some surfaces, like the inside of the furnace or air handler, are cleaned via contact vacuuming. Others, like ductwork, are put under negative pressure with a vacuum collection unit and then the accumulated dirt and debris are dislodged with air washing and power brushing tools.

This dirt and debris is collected (using the negative pressure or suction from the vacuum collection unit) and blown (using air washing tools) to the vacuum collection unit. Coils can be cleaned via air washing, contact vacuuming, or with coil cleaning solutions and water.

If microbial contamination is a concern, the system can be cleaned and then sanitized. In some systems there is fiberglass insulation. In many of these systems this insulation has deteriorated over time and must either be replaced or repaired. The ultimate goal is to remove all of the accumulated dirt, debris, and other contamination found in the system. This is called source removal.

The National Air Duct Cleaners Association (NADCA) has developed a list of basic cleaning tasks for residential air duct cleaning. This list includes: visual inspection before and after cleaning; remove, clean, and replace supply registers and return grilles; clean supply ductwork and plenum; clean return ductwork and plenum; install access openings as needed and reseal after cleaning; clean blower motor and assembly; clean airsteam side of heat exchanger; clean secondary heat exchanger; clean evaporator coil and drain pan, wash air cleaner; and replace air filter.

In addition, many contractors also offer system sanitizing, dryer vent cleaning, and installation of UV lights.

NADCA has also published a document called ACR 2006 -Assessment, Cleaning, and Restoration of HVAC Systems. This document is the basis for many commercial cleaning specifications today. These commercial specifications spell out what is required on that project. Typically you need to clean anything in the airstream of the HVAC system.

There are three main types/levels of cleaning used to clean ductwork allowing contractors to achieve source removal of the accumulated dirt and debris.

The first level is air washing only. Air washing is the use of high-pressure air that comes from an air compressor through an air hose to an air nozzle. This air nozzle delivers the streams of high-pressure air, which dislodges the accumulated dirt and debris. The suction from the vacuum collection system and the high-pressure air from the air nozzle move the dirt and debris that has been dislodged from the ductwork into the vacuum collection system.

The next level of cleaning is achieved by using air whips. Air whips are a combination of air washing (high-pressure air) with some agitation from the whips. This is a higher level of cleaning because - in addition to air washing - the whips make contact with some of the interior ductwork.

Again, the suction from the vacuum collection system and the high-pressure air from the air nozzle move the dirt and debris that has been dislodged from the ductwork into the vacuum collection system.

The highest level of cleaning is achieved by power brushing and air washing because it does the best job of removing the accumulated dirt and debris in the ductwork. The brushing does the best job of dislodging the accumulated dirt and debris because it is making physical contact with more of the interior ductwork than the other methods. Air washing after brushing is necessary to help move any remaining dirt and debris out of the ductwork to the vacuum collection system.

An example of different levels of cleaning quality is washing your car. There are car washes that use just high-pressure water with soap and others use high-pressure water, soap, and brushes. Both clean your car but which method gets it cleaner? Brushing gets your car cleaner because it makes physical contact with most of your car. Likewise, brushing cleans ductwork better because it makes physical contact with most of the ductwork.

Like brushing with air washing, contact vacuuming achieves very good cleaning results. Contact vacuuming is done with a HEPA filtered portable vacuum and is the primary method when cleaning air handlers, rooftop units, and furnaces. When this method is used for cleaning ductwork many access openings are required.

2. What equipment is needed?

Let's start with a basic explanation of the different types of vacuum collection systems that are available.

The large truck-mounted units offer lots of suction so you typically do not have to zone off the system. These units sit outside and a large 50- to 100-foot long suction hose is brought into the home or building and connected to the ductwork. You are limited to cleaning residential and one- or two-story commercial buildings with the truck-mounted units. These units are also the most expensive and require the most maintenance.

Trailer-mounted and portable gas vacuum collection systems are less expensive than truck-mounted units, but like them, they sit outside and you bring in the suction hose to connect to the ductwork. Depending on the system, you may or may not have to zone off the system to achieve the suction you need to effectiviely clean. You are limited to cleaning residential and one- or two-story commercial buildings.

Portable electric vacuum collection systems offer the most flexibility in that you can clean virtually any type of building with them, including houses, apartments, condos, light commercial, and commercial. You bring these collectors into the building and position them where you can be the most productive. You zone off and divide up the HVAC system to achieve the suction you need to clean. These units operate on 110 or 220 V, 50 or 60 H, and have HEPA filtration.

The level of cleaning and the level of service the contractor decides to offer will determine what type of specific equipment is necessary.

In generic terms a typical equipment package to inspect, clean and decontaminate HVAC systems will include: a vacuum collection system that puts ductwork under negative pressure (suction); agitation tools used to dislodge accumulated dirt, debris, and contaminants; power brushing system(s); air whip system(s); air washing tools; an air compressor that provides high-pressure air for air washing tools and air whips; a HEPA filtered wet-dry vac used to contact vacuum surfaces; duct accessing tools and service panels used to cut access openings, isolate, and closing access openings; visual inspection system used to show client pre- (existing) and post- (after cleaning) conditions in the ductwork; chemicals and chemical dispensing tools; sanitizer and fogger, coil cleaner, degreaser, etc.; personal safety equipment; and miscellaneous items (hand tools, ladders, drop cloths, etc). Plus you may need a truck or trailer to transport the equipment.

3. What does it cost to get into air duct cleaning?

The cost to get into air duct cleaning will be determined by the type of air duct cleaning you want to offer (residential or commercial or both). Initial cost also depends on the type of equipment you select and the level of cleaning services you want to offer. This cost will range from $8,000 to over $20,000. Equipment suppliers can typically give you several equipment options to choose from that will best fit your needs and budget.

The company offers free copies of its "Blueprint for Success Guidelines." For information on aspects of air duct cleaning, contact 800-597-3955, 952-808-1616, or phaugen@vacsysint.com.

Publication date: 10/02/2006