Category: Understanding Ventilation Systems

Planning for Air Conditioning Installation

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If you are planning on installing an air conditioner before the weather heats up, it is important to have the air ducts cleaned before the air conditioner is installed.  Having the air ducts cleaned before the air conditioning is installed will prevent numerous avoidable problems from occurring.

Prevent a Dust Out

When central air conditioners are installed, numerous modifications are made to the furnace cabinet and supply trunk line.  Trunk lines are the main intake and distribution lines of an HVAC system.  Because of the volume of air that is circulated through trunk lines, they are often the dirtiest points of a ventilation system.  Modifications to the trunk lines disrupt and loosen debris on the walls of the trunk lines.  If the air duct are not cleaned prior to installation there is a high probability of drawing debris into your newly installed HVAC components or blowing the loosened dust and debris within your home.

Prevent Fouled Air Conditioning Coils

Home central air conditioning systems draw air from the return air vents; and blow the air through evaporative coils located above the furnace to chill the air.  To a large degree, the energy efficiency of an air conditioner is dependent on the cleanliness of the evaporative coil. When evaporative coils become fouled, they cause a number of problems:

  • Decrease heat transfer: Evaporative coils are made of tiny fins designed to absorb the heat from the air, when dirt or debris enters the coil fins, it acts as an insulator preventing efficient heat transfer.
  • Decrease airflow: Debris can build within the coil face preventing air to freely flow through the coil.  Fouled air conditioning coils negatively affect your HVAC system during the heating season as well.
  • Clogged drain pans: As evaporative air conditioner coils absorb heat from the air, they condensate moisture which flows from the air conditioning system through a drain pan.  Moisture and debris clogs the drain of the air conditioner.
  • Coil Freeze: Loosened debris within the air ducts causes air filters to load prematurely, and fouls evaporative air conditioner coils. Coils typically freeze and fail due to low air flow.

Plan and Prepare

When planning your air conditioner installation, budget air duct cleaning in your installation cost.  Coordinate the air duct cleaning to be performed before the installation of the air conditioner.  Clean air ducts will provide numerous long term benefits.

NADCA Energy Research Study

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For decades the National Air Duct Cleaners Association (NADCA), has been educating consumers on the process and benefits of air duct cleaning. Currently there is research study underway to measure the correlation between energy pressure drop and energy savings.

NADCA Energy Research Study

In February 2008, NADCA entered into a partnership with the Colorado University to conduct a research project that will provide members with a tool for estimating the energy savings associated with HVAC cleaning and restoration projects. The research project was also commissioned to develop a field-testing protocol for NADCA members that will facilitate collection of data to provide broader support for linking HVAC cleaning and restoration to energy savings.

Current Findings and Test Results

NADCA presented the current results of the test at the 2010 Annual Meeting.  Comparisons were made by testing air flow rates when the filter, furnace, and evaporative air conditioner coil were fouled and again when the components were clean.

It was found that a dirty filter increased the filter pressure drop, system pressure drop and reduced the air flow of the ventilation system.

Surprisingly, a clean furnace and evaporative air conditioner coil increases initial energy consumption, but lessoned the amount of time that the furnace an air conditioner had to operate to achieve the desired room temperature. Though there was initial higher energy consumption, there was a net gain in overall energy efficiency.

While further data and testing is required, the current the findings show that proper exchange rate and selection of the furnace filter, routine cleaning of the evaporative air conditioner coil, and sealing of air ducts offer the greatest benefits to energy savings.

Further Testing Underway

Currently NADCA is receiving further test results from companies engaged in the assessment, cleaning, and restoration of HVAC systems.  These test results are being sent to the University of Colorado for further interpretation.

Air Pollution in Energy Efficient Homes

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Air sealing the building envelope is one of the most critical features of an energy efficient home.  As new homes grow increasingly tighter to achieve ever higher levels of energy efficiency, the potential for indoor air pollution also increases.

Modern Construction

During construction, there are hundreds of penetrations through a typical home’s exterior. These gaps and holes are often incurred during framing, and from penetrations for wiring, plumbing, and ducts.  Air leakage accounts for 25–40% of the energy used for heating and cooling in a typical home.  To make a home energy efficient, these gaps and holes are closed and insulated to prevent the loss of conditioned air.

Indoor Air Quality Concern

Good indoor air quality is achieved by reducing or eliminating sources of indoor air contamination and providing sufficient fresh air through the heating and ventilation system.  While older homes were not energy efficient, they typically did not have problems with indoor air quality because they allowed for fresh air to freely circulate within the home.

As new homes grow increasingly tighter to achieve ever higher levels of energy efficiency, potential indoor air pollution also increases since many conventional building materials emit volatile organic compounds like formaldehyde.  While energy efficiency is important, gains in energy efficiency, especially in new homes, should not come at the expense of deterioration of indoor air quality and corresponding adverse health impacts.

Source Elimination and Control

The best way to address indoor air pollution is through aggressive source elimination and control.  Pollution should be prevented or reduced at the source whenever feasible.

  • Building materials:  If you are having the home constructed or remodeling your home select materials that do not emit volatile organic compounds.
  • HVAC System: Make sure your HVAC system distributes the minimum level of outdoor air throughout the home using whole-house mechanical ventilation.
  • Sealing Air Ducts:  Sealing ducts can help improve indoor air quality by reducing the risk of pollutants entering ducts and circulating through your home as well as preventing the loss of conditioned air.
  • Air Duct Cleaning: Ventilation systems distribute the air you breathe. Have the air ducts and HVAC system professionally cleaned to remove construction debris and pollutants.
  • Monitor use of household cleaning supplies:  Some household chemicals can be extremely dangerous.  Choose environmentally safe cleaning supplies, and make sure that the area is well ventilated.
  • Check exhaust systems:  Make sure exhaust fans are clean and unobstructed. Exhaust systems are responsible for removing moisture, odors, fumes, and carbon monoxide.

Top 10 Ways Homeowners Can Ensure Good Indoor Air Quality

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Ensuring good indoor air quality is easy once you have an understanding of the components that effect your homes environment.  Using the steps below, perform a quick checklist to improve your indoor quality.

Setting the Standard for Indoor Air Quality

ASHRAE, the American Society of Heating, Refrigeration and Air Conditioning Engineers developed Standard 62.2, Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings.  The standard, which is widely accepted by green builders, state and local around the counties, defines the roles of and minimum requirements for mechanical and natural ventilation systems and the building envelope in order to provide acceptable IAQ in low-rise residential buildings.

10 Steps to Ensure Good Indoor Air Quality

  1. Vent bathrooms, kitchens, toilets and laundry rooms directly outdoors.  Use energy efficient and quiet fans.
  2. Avoid locating furnaces, air conditioners and ductwork in garages or other spaces where they can inadvertently draw contaminants into the house.
  3. Properly vent fireplaces, wood stoves, and other hearth products; use tight doors and outdoor air intakes when possible.
  4. Vent cloths dryers and central vacuum cleaners directly outdoors.
  5. Store toxic or volatile compounds such as paints, solvents, cleaners, and pesticides out of the occupiable space.
  6. Minimize or avoid unvented combustion sources such as candles, cigarettes, indoor barbecues, decorative combustion appliances or vent free heaters.
  7. Provide operable windows to accommodate unusual sources or high-polluting events, such as the use of home cleaning products, hobby activities, etc.
  8. Use sealed-combustion, power-vented or condensing water heaters and furnaces.  When natural-draft applications must be used, they should be tested for proper venting and should be located outside the occupied space when possible.
  9. Put a good particle filter or air cleaner in your air handling system to keep dirt out of the air and off your ductwork and heating and cooling components.
  10. Distribute a minimum level of outdoor air throughout the home using whole-house mechanical ventilation.

Source: ASHRAE Standard 62.2 Ventilation and Acceptable Indoor Air Quality on Low-Rise Residential Buildings, and 2001 ASHRAE Handbook, Fundamentals, Chapter 26, Ventilation and Infiltration.

Air Duct Cleaning Tools

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Qualified air duct cleaning contractors employ a variety of different power, pneumatic and hand tools when cleaning air ducts.  While there are numerous types of equipment used in the air duct cleaning industry, the job site to a large extent, defines what air duct cleaning tools will be used.

Breaking Contaminants Loose

Properly cleaning HVAC systems requires removing the sources of contamination from the walls of the air ducts.  Just as there are numerous types and sizes of air ducts, they are numerous air duct cleaning tools used to loosen debris from the walls of the air ducts.

  • Mechanical Agitation: Mechanical air duct cleaning tools are typically brushes powered through an electric motor, and are generally used for sheet metal air ducts.  Mechanical air duct cleaning tools are primarily used for more aggressive cleaning applications.
  • Pneumatic Agitation: Pneumatic air duct cleaning tools utilize compressed air to agitate debris from the walls of the air ducts.  There are numerous pneumatic air duct cleaning tools that can be used such as air whips, compressed air nozzles, or skipper balls.  Pneumatic air duct cleaning tools are primarily used to clean sensitive materials such as internally lined fiberglass air ducts, fiberglass duct board, and flex line air ducts.
  • Hand-brush & Contact Vacuuming: When accessible, hand brushing and contact vacuuming with a HEPA filtered hand vacuum is always the most effective method of cleaning.

Collection of Contaminants

A vacuum is the most commonly used air duct cleaning tool in the air duct cleaning industry.  The most important consideration for every ventilation cleaning project is the prevention of cross contamination. During air duct cleaning, the entire HVAC system is placed under negative pressure (vacuum) to collect loosened debris and prevent the spread of contaminants.  There are two main types of collection devices:

  • Truck Mounted Vacuums: Truck Mounted Vacuums are gas powered vacuums that are powered through the PTO of an operating vehicle.  The amount of vacuum typically ranges from 10,000 – 15,000 cfm.  Because of the high volume of air the Truck Mounted Vacuum draws, they have a high propensity for drawing vehicle exhaust and contaminants within the workspace.
  • Portable HEPA filtered Vacuums: In most instances, portable HEPA filtered vacuums are the most effective vacuum collection device.  HEPA filtered vacuums have a high velocity of vacuum draw allowing for greater lift of the debris and can often be brought to the contaminant source.  HEPA filters prevent contaminants from being dispersed from the vacuum exhaust and prevent the potential of cross contamination.

Fiberglass Air Duct Liners | A Serious Indoor Air Quality Concern

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Most commercial air duct systems are internally lined with fiberglass duct liners.  Deteriorating fiberglass duct liner is a very common cause for indoor air quality complaints and adverse health effects.

Fiberglass Duct Liner

Fiberglass internal duct liner is commonly used in many commercial heating, ventilation, and air conditioning (HVAC) system.  Fiberglass duct liner provides sound attenuation by dampening noise from HVAC equipment, and sound from adjacent office spaces.  Fiberglass duct liner provides thermal insulation for air ducts, preventing the air ducts from losing expensive conditioned air.

Fiberglass Duct Liner Deterioration

Over time internal fiberglass duct liner is exposed to varying degrees of air turbulence, temperature and humidity.  These environmental changes take its toll on the duct liner, breaking down its primary seal.

The primary seal is a black gritty coating on the surface of the duct liner which locks down the fiberglass fibers.  Deteriorated primary coating migrates through the ventilation system depositing within HVAC components and eventually entering the indoor air.

After the primary seal has fully deteriorated, it allows raw fiberglass fibers to be exposed to the airstream.  Turbulent airstreams wick the raw fiberglass fibers through the ventilation system, creating additional deposits within HVAC components and exposing building occupants to raw fiberglass fibers.

Health Effects of Fiber Glass Fibers

Health effects from exposure to fiberglass can be different depending on the fiber size and type of exposure.  Fiberglass, at a minimum, is an acute physical irritant to the skin, eyes, and upper respiratory tract.

  • While no long-term health effects should occur from touching fiberglass. Rashes can appear when the fibers become embedded in the outer layer of the skin.
  • Eyes may become red and irritated after exposure to fiberglass as occupants touch horizontal surfaces with deposits of fiberglass fibers, and rub their eyes.
  • Soreness in the nose and throat can result when fibers are inhaled. Asthma and bronchitis can be aggravated by exposure to fiberglass.
  • Temporary stomach irritation may occur if fibers are swallowed.

How Can Fiberglass Air Ducts Be Repaired?

If caught in the early stages of deterioration the internal fiberglass duct liner can be repaired.  Fiberglass duct liner can be resurfaced with an encapsulate specifically designed for HVAC systems.   Initially a commercial air duct cleaning needs to be performed to remove the foreign debris from the air duct surface to ensure for a proper bond.  After the air duct system is cleaned, the encapsulate is applied to the air duct surface locking down the fiberglass fibers.

If the internal fiberglass lining to too deteriorated, the lining must be removed and replaced.  If the damage is localized,  new internal internal insulation can be installed within the ducting.  If the damage is extensive, consider removing the damaged insulation and wrapping the air ducts with an external fiberglass insulation.

Prevent A Dryer Vent Fire

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A clothes dryer works by forcing hot air through a turning drum. Wet clothes placed in the drum are then dried by the moving hot air. It is possible for a full load of wet clothes to contain as much as one and a half gallons of water from a typical load of laundry.  Lint is created from the clothes as the water is removed and the clothes dry.  Overtime as air passes through this exhaust line the lint collects in the screws, bends and elbows and walls of the air duct.

Inspect the Type of Air Duct Attached to the Dryer

Most manufacturers specify the use of a rigid or corrugated semi-rigid metal duct, which provides maximum airflow. Flexible plastic or foil type duct can more easily trap lint and is more susceptible to kinks or crushing, which can greatly reduce the airflow.  Replace plastic or foil, accordion-type ducting material with rigid or corrugated semi-rigid metal duct.

Fire Hazard

Clothes dryer fires account for about 15,600 structure fires, 15 deaths, and 400 injuries annually. Fires can occur when lint builds up in the dryer or in the exhaust duct. Lint can block the flow of air, cause excessive heat build-up, and result in a fire in some dryers.

Air Flow Restriction

New construction trends now situate wash­ers and dryers in nontraditional areas of the house, such as upstairs bedrooms, hallways, bathrooms, kitchens, and closets. These new sites generally require longer dryer vents, and a higher probability for air flow restriction.

Dryer Vent Maintenance and Safety Tips

Proper maintenance for clothes dryers involves removing the lint from the traps, vents, and surrounding areas of the dryer.

  • Never operate your clothes dryer when you are not home or while you are sleeping.
  • Clean your lint trap before or after every use.
  • Install a proper screen to the outside exhaust to prevent animals from entering the dryer vent.
  • Do not push your dryer too close to the wall as it may cause crimps or bends in the air duct.
  • Periodically have the dryer vent professionally cleaned.

Smoke and Fire Damaged Air Ducts

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An air duct system is very efficient at spreading smoke.  When a fire occurs, the entire HVAC system will be contaminated, to a lesser or greater degree.  It is likely that the air duct system will distribute smoke damage well beyond the area of the fire.

Smoke Damage from an Active Air Duct System

Unfortunately, a forced air ventilation system is rather effective at spreading smoke damage.  Smoke is drawn into return air vents, through the furnace components, and distributed throughout the home or building through the supply air ducts.  If the HVAC system was operating at the time of fire, the return air side will be the most contaminated.

Passive Air Duct Smoke Damage

Even if the heating and ventilation system is not in use, there is a natural or passive air movement throughout the ventilation system.  If the air duct system wan not in operation during the fire, the return and supply air ducts closest to the fire will be the most contaminated.

Absorption of Odors

Smoke is naturally attracted to metal surfaces and is corrosive in nature.  As the smoke enters the air ducts it will cling to the steel, and will absorb into the debris within the air duct system.  A ventilation system has to be thoroughly cleaned in order to remove smoke damage.

Odor Oxidizer

After the ventilation system has been cleaned, an odor oxidizer is applied within the air ducts.  An odor oxidizer naturally breaks downs the odor causing chemicals of the smoke damage.

Encapsulation

In some instances of extreme smoke damage, air ducts will need to be encapsulated to remediate the smoke damage.  After the air ducts are cleaned, an encapsulates approved for use within HVAC systems is applied uniformly throughout the ventilation system.

Green Air Duct Cleaning


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Green air duct cleaners employ advanced methods and materials specifically for green cleaning.   They make an extra effort to not allow any dust to escape outdoors or indoors, and only use natural cleaning products.

Clean & Maintained Air Duct Cleaning Equipment

Green air duct cleaning companies ensure that equipment is cleaned and maintained to prevent introducing contaminants into the home or business.  HEPA vacuums require routine inspection to ensure that the filter is properly sealed and operating at peak performance.  HEPA filtered vacuums to prevent dust from being re-released into the air.

No Dust Escapes

No dust should enter your home or be released outside during the air duct cleaning process. Green air duct cleaning companies use source removal cleaning procedures to mechanically agitate and HEPA vacuum debris from the wall of the air ducts.

Green Cleaning Products

Cleaning solvents are needed to clean debris air vent vent registers and furnace components.  Only non-toxic, biodegradable, non-corrosive, non-flammable, environmentally safe cleaning products are to be used.

Limited Use of Sanitizers

Sanitizing agents should  ONLY be used if there is microbial problem. Any sanitizer used in the HVAC system must be specifically registered by the EPA or other applicable regulatory agency for the use in HVAC systems.

Never Use Scented Sprays

Green air duct cleaning companies never use scented spays within air ducts.  A proper cleaning of the air vents will remove the debris harboring the odor.  Scented sprays mask odors, and can potentially cause an adverse reaction to home or building occupants.

Understanding Indoor Air Pollutants

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A host of different biological, gas, and particulate pollutants can affect the indoor air quality.  The types of contaminants and the amounts that are suspended in the air determine air quality.

Biological Air Pollutants

Biological pollutants are or were living organisms. While all of us are exposed to biological pollutants in one form or another, the effects on our health depend upon the type and amount of biological pollution and the individual person.  Two conditions are essential to support biological growth – nutrients and moisture.  Keeping an area clean and dry is the best method to prevent biological air pollutants.

Common biological air pollutants:

  • Pet Hair & Pet Dander
  • Mold
  • Dust Mites
  • Pollen
  • Cockroach parts

Chemical & Gas Air Pollutants

Chemical and gas pollutants are the most hazardous of all air pollutants as they are often odorless, tasteless and invisible.  Ensuring proper exhaust, using building products with low levels of volatile organic compounds, and prohibiting smoking indoors are the best methods for preventing chemical and gas air pollutants.

Common chemical & gas pollutants:

  • Carbon Monoxide
  • Radon
  • Smoke
  • Building Materials with volatile organic compounds

Particulate Air Pollutants

Particulate air pollutants are particulates that have the ability to become air born when disrupted. The size of particles is directly linked to their potential for causing health problems. Particles that are 10 micrometers in diameter or smaller are of greatest concern because they can pass through the throat and nose and enter the lungs.  Good house keeping and construction containment practices are the best methods for lowering particulate air pollutants.

Common particulate air pollutants:

  • Drywall
  • Fiberglass
  • Concrete
  • Carpet fibers
  • Sawdust