Category: Understanding Ventilation Systems

Air Pathways and Indoor Air Quality

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Air pathways are a key component of indoor air quality. Understanding and improving air pathways will greatly improve your indoor air quality.

Understanding Air Pathways

Air flow is created by pressure differentials.  Air flow always flows from higher relative pressure to lower relative pressure.  Air will flow through any available opening (pathway) in an attempt to equalize pressure.  Pathways include windows, doors, electrical outlets, floor drains, heating and cooling systems, and most importantly air ducts.

Air Pathways within a Home

A forced air system works by creating a difference in pressure between the area where the supply registers are located and the area where the returns are located.  As air moves from supply diffuser to return air grill, it is diverted or obstructed by partitions, creating pathways of air movement throughout the home.

How do Air Pathways affect a Home?

Pathways can change from one minute to the next – Opened windows, an exhaust fan, open/closed doors etc… Unintended pathways need to be acknowledged to have a comprehensive understanding of a homes airflow patterns.

Improving Air Pathways

Air ducts are the pathways for energy efficient homes.  With a couple of simple steps you can improve your air pathways.

  • Seal the air ducts to prevent costly, conditioned air flow from being drawn from or escape into unknown, unspecified, or unintended areas of the home.
  • Filter the air by changing the furnace or air conditioning air filter.
  • Make sure that air ducts are not blocked by interior furnishings that prevent their designed use.
  • Have the air ducts cleaned to prevent obstructions in air flow.
  • Use bathroom exhaust fans when using the shower to exhaust moisture.
  • Use kitchen exhaust fans when cooking to exhaust fumes from cooking.
  • Have your HVAC technician inspect exhaust flues when they perform annual HVAC inspections to ensure carbon monoxide is properly exhausted.

Improve Indoor Air Quality by Understanding Air Pressurization

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Several factors contribute to poor indoor air quality that can be easily controlled. Air pressurization greatly affects the indoor air quality of a home or building.

Pressurization

Air flow is created by pressure differentials.  Air flow always flows from higher relative pressure to lower relative pressure.  If more air is supplied to a room than exhausted, the excess air leaks out of the space and the room is said to be under Positive Pressure.  If less air is supplied than exhausted, air is pulled into the space and the room is said to be under Negative Pressure.

Positive Pressure

If a home or building has too much positive air pressure, it will allow for conditioned air to escape the home causing costly energy concerns.

Negative Pressure

Negatively pressurized homes allow for unconditioned and unfiltered air to be drawn within the home or building.  Debris will enter through cracks and crevices, opened doors, windows, etc…

What’s the Ideal Air Pressurization?

It is ideal to achieve neutral to slightly positive air pressurization.  Though there is a slight loss of conditioned air, a slightly positive pressured home will provide comfort and prevent outdoor contaminants from entering the home or building.

ASHRAE Standard 62.1 “Ventilation for Acceptable Indoor Air Quality” requires proper ventilation and a slightly positive pressurization of buildings. Maintaining a small positive air pressure, relative to the outdoors, limits the entrance of outdoor moisture and is a very common strategy to prevent mold and mildew formation in a building.

How Can You Monitor or Control Air Pressurization?

Air pressure can be monitored through an energy auditor.  An energy auditor will use of a blower door & smoke test to determine the location of air leaks.  After the test is performed steps can be made to improve air pressurization.

Several factors contribute to poor indoor air quality that can be easily controlled. Air pressurization greatly affects the indoor air quality of a home or building.

Pressurization

Air flow is created by pressure differentials.Air flow always flows from higher relative pressure to lower relative pressure.If more air is supplied to a room than exhausted, the excess air leaks out of the space and the room is said to be under Positive Pressure.If less air is supplied than exhausted, air is pulled into the space and the room is said to be under Negative Pressure.

Positive Pressure

If a home or building has too much positive air pressure, it will allow for conditioned air to escape the home causing costly energy concerns.

Negative Pressure

Negatively pressurized homes allow for unconditioned and unfiltered air to be drawn within the home or building.Debris will enter through cracks and crevices, opened doors, windows, etc…

What’s the Ideal Air Pressurization?

It is ideal to achieve neutral to slightly positive air pressurization.Though there is a slight loss of conditioned air, a slightly positive pressured home will provide comfort and prevent outdoor contaminants from entering the home or building.

ASHRAE Standard 62.1 “Ventilation for Acceptable Indoor Air Quality” requires proper ventilation and a slightly positive pressurization of buildings. Maintaining a small positive air pressure, relative to the outdoors, limits the entrance of outdoor moisture and is a very common strategy to prevent mold and mildew formation in a building.

How Can You Monitor or Control Air Pressurization?

Air pressure can be monitored through an energy auditor.An energy auditor will use of a blower door & smoke test to determine the location of air leaks.After the test is performed steps can be made to improve air pressurization.

10 Tips to Lowering Dust Within Your Home 


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While you will never be able to completely rid your home of dust.  Here are 10 great tips to reduce the amount of dust and other allergy-aggravating particles from your home.

Establish a Regular Cleaning Schedule

When there are long periods of time between cleanings it makes the work much harder.  Develop a routine cleaning schedule, it will help ensure that the maintenance is routine and that areas are not overlooked.

Remove Shoes

Not only does taking your shoes off at the door save the carpets, it also prevents dirt, dust, pollen, and other debris from getting tracked throughout the house. Use of mats placed inside and out of all entrances will help cut down on dust.

Dusting Techniques

When dusting your home, the goal is to capture the dust, do not use a feather duster, as they only stir up dust. When dusting objects within your home work from the top of the object down using a damp cloth, or an anti-static cloth to capture the dust.

Furniture

Vacuum upholstered furniture weekly.  Most vacuum cleaners come with a hose and attachments to make this an easy task.  Remove all the cushions, and vacuum them separately. Clean the back, sides and make sure to clean underneath the furniture too

Window Treatments

Dust window treatments monthly.  Window treatments can hold a lot of dust which can get released into the air if they are brushed up against or touched.

Carpets

Carpets are the perfect resting spot for dust and pet dander. Vacuum all carpets at least once a week.  Be sure to use high efficiency vacuum bags, low efficiency vacuum bags will allow for fine dust to re-enter the air.

Bedding

Lots of mites and dust get trapped in bedding.  Bedding collects skin flakes, sheds its own fibers and releases dust every time you roll over.  Wash bedding weekly in hot water & don’t forget to vacuum under your bed.

Inspect Your Dryer Vent Exhaust

Once a year inspect your dryer vent exhaust. Your dryer is responsible for exhausting moisture and lint from your clothing, and can potentially be the culprit for dust in your home.  Make sure that the dryer isn’t shoved against the wall, and that the dryer exhaust line is firmly attached.  Clean out your lint trap regularly & have the dryer vent cleaned when needed.

Change Filters on Heating & Air Conditioning Unit

Change the air filters every two months that the heating or air conditioning system is in use.  Use good air filters with a MERV rating between 7 and 11.

Keep Your Air Ducts Clean

Overtime dirt and dust build up within the air ducts.  Dirty air ducts will re-circulate dust within your home.  Typically air ducts need to be cleaned every 3-5 years.

Types of Air Ducts

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Air ducts are used to distribute air through out a building, or to exhaust air outside of a building. The most common are: sheet metal, fiberglass lined, fiberboard, and flex-line air ducts.

Sheet Metal Air Ducts

The most common type of ridged air duct is constructed of galvanized steel or aluminum. They may be round, rectangular, or in the form of a spiral oval.  Sheet metal air ducts are the most durable type of air duct construction, and because their non-porous surface, are the least likely to have mold or biological growth.

Fiberglass Lined Air Ducts

Some sheet metal air ducts air ducts are lined with an external or internal fiberglass duct liner. Fiberglass lining is used to insulate air ducts from heat loss or to avoid condensation in cases where the supply air is very cold, or there is a high ambient humidity in the plenum.  Fiberglass lining also provides sound attenuation, reducing the noise of the HVAC system.

Fiberboard Air Ducts

Fiberboard air ducts are constructed with boards of compressed resin bonded inorganic glass fibers.  They have a foil face on the outside that serves as the air barrier and water vapor retarder.  The interior of fiberboard air duct is sealed to prevent fiberglass fibers from entering the air stream.  Fiberboard air duct also provide acoustical and thermal benefits, and are typically the most inexpensive air duct systems to install.

Flexible Air Ducts

Flexible air ducts are constructed with a spring steel wire helix, encapsulated in a 2-ply, polymer plastic. Flexible air ducts are inexpensive, lightweight, and easy to install.  It is important that the lengths of the flexible air ducts be kept as short as possible as the length of flexible, and numbers bends within the flexible greatly effects system performance.

Care for Your Air Conditioning System

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Air conditioning units require regular maintenance to keep them working at an optimal level. Follow these guidelines to ensure your air conditioner is working efficiently.

Conduct Regular Maintenance

Hire a professional HVAC person to regularly inspect your air conditioning system.  Make any necessary repairs in a timely manner. The longer you put off repairs, the more expensive they can become.

A typical air conditioner service will:

  • Check for proper refrigerant (freon) levels.
  • Check all electrical components and controls.
  • Clean evaporator and condenser coils.
  • Oil motors as needed.
  • Calibrate thermostat.
  • Check filters.

Change Filters

Routinely check and replace filters. Use the highest rated filter recommended by the manufacturer and make sure to install it properly.  There should be no gaps or leaks around the edge of the filter.

Use a Good Thermostat

Control indoor air temperature with a good thermostat. A good thermostat can operate air conditioner to a lower setting saving energy while you are at work, or while sleeping.

Keep Air Ducts Clean

Have your air duct cleaned every three to five years.  Excessive build up of dust and debris in air ducts can cause blocked or limited airflow, reducing the effectiveness of the air conditioner.

Is It Time For You Have The Air Ducts in Your Home Cleaned?

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You may have heard about having your air ducts cleaned, but how do you know if you need to? Here are a few tips to help you decide if the time is right for you to clean you air ducts.

Ask Your HVAC Maintenance Technician

The next time you have your heating or air conditioning unit maintained, ask the technicians opinion about your air duct cleaning needs. Since they are not trying to sell you their cleaning services you will likely get an honest answer.

Inspect Your Air Ducts

Inspecting the condition of the air ducts is relatively simple.  The best place to inspect the condition of the air ducts is at the trunk line.  The trunk line is the large rectangular air duct attached to the furnace, extending overhead across the basement area.  Locate a vent register on the trunk line, and remove it with a screw driver.  Look inside the trunk line with a flashlight and mirror, or take a snapshot with a digital camera.  The trunk line is the central part of the heating and cooing system and will be the best indicator of the systems cleanliness.

Dirty Air Ducts Can Be a Fire Hazard

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All dust can be a fire hazard and regular household dust is no exception. Help keep your home safe by cleaning air ducts and preventing an accumulation of dust.

How is Dust Dangerous?

Accumulated dust can pose a fire hazard, as all dust is flammable. Ignition of dust can happen in two ways, by a spark of energy, or an extremely hot surface.

Fire Hazards in the Furnace

Air within your home is heated through the burners and heat exchanger of the furnace. Burners heat the heat exchanger to an extremely high temperature.  Above the furnace, within the plenum dust accumulates over time and will occasionally drop onto the top of the heat exchanger.  If the amount of debris is large enough, there is a strong potential of a fire within the furnace.

Fire Hazards from the Furnace Filter

Furnace filters are designed to protect the furnace and air conditioner from dust.  If the filter is not changed regularly dust can accumulate to the point that the filter can collapse and be sucked into the furnace cabinet and cause a fire.

Cleaning Air Ducts

The only way to reduce fire hazard from dust is to reduce the amount of dust. Cleaning air ducts is the easiest, most effective way to eliminate dust build up and prevent potential hazards from forming.  Choose a professional air duct cleaning company as improperly cleaned air ducts may actually cause more loose dust to circulate, creating more of a hazard.

Pet Dander Can Affect Your Air Quality

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Pet Dander is one of those microscopic particles found in many homes that can cause allergic reactions and trigger asthma. Here is some more information about pet dander and what you can do to reduce the amount of it in your home.

What is Pet Dander?

Pet dander is not animal hair; it is the tiny bits of skin flakes skin produced by every animal. Many people think they are allergic to cat or dog hair, but most are allergic to dander. Some people are severely allergic to pet dander, while others have less severe reactions.

Where is Pet Dander Found?

Pet dander is found anywhere pets are found. All animals shed hair and skin and leave traces of it behind everywhere the go. Dander is often so small that it can become airborne and reach the tops of surfaces that pets do not go, so just because Fido does not sit on the couch that does not mean that dander cannot be found on the couch. Pet dander can also stick to people’s hair, skin, and clothing that come in contact with animals, their bedding, or places animals have been.

How Do You Control Pet Dander?

Keep pet dander at a minimum by cleaning and dusting frequently. Wash animals and their bedding and brush them outdoors. Offer pets their own place to sit and sleep rather than allowing them on furniture.

What If I am Allergic to Pet Dander?

The best way of controlling allergic reactions is avoidance. If you are unwilling to part with the animal consider the following suggestions:

  • Receive treatment or consultation from an Allergist.
  • Make sure to wash your hands after petting any animal and never rub your eyes.
  • Wear a protective mask and gloves when grooming.
  • Litter boxes should be placed in an area unconnected to the air supply for the rest of the home.
  • Keep pets off furniture.
  • Change clothing worn after grooming or playing with pets.
  • HVAC systems can spread allergens throughout the home, change the furnace filter regularly, and keep the air ducts clean.

5 Tips to Keep You Furnace Efficient 


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To keep your heating bills low, you need to keep your furnace running efficiently. Here are 5 tips to keep your furnace working at peak performance.

Before Winter, Have Furnace Inspected

Before the first use, have the have the furnace inspected by a professional HVAC contractor.  The furnace contractor will inspect the furnace to make sure that the furnace is operating safely and efficiently.

Replace Filters

Replace the furnace filter every 2 months that the system is in use. Clogged air filters make it difficult to for the furnace to draw air. Furnace filters protect the furnace components from dirt which will cause damage to furnace components and dramatically decrease energy efficiency.

De-Clutter the Furnace Area

Keep the area around the furnace clean and clear of clutter. This reduces fire hazard and makes sure the furnace can get all the air it needs for proper combustion.

Use Your Thermostat Properly

If your thermostat is set at a constant temperature, consider setting the thermostat a few degrees cooler at night while you are sleeping, and during the day when you are at work.  Setting your thermostat properly will dramatically reduce your furnace bill.

Keep Your Air Ducts Clean

Nine out of ten HVAC failures are due to dirt and debris accumulation.  Keeping your air ducts clean will reduce the impact of debris build up on the furnace filter and HVAC components.  Have the air ducts professionally cleaned every three to five years.

Easy Tips to Keep Your Ducts Clean

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Keeping air ducts clean can help keep indoor air quality healthy. Follow these simple tips to reduce dust and other build up in your air ducts.

Change Furnace Filters

Routine air filter maintenance is the most effective means of keeping your air ducts clean. Proper selection, routine exchange, and the proper fit of you furnace filter will dramatically extend the longevity of your air duct cleaning.

Perform An Air Duct Inspection

After the cleaning has been performed conduct an air duct inspection.  Thoroughly look over your air ducts for any evidence of leaks, damage, or gaps.  It is important that air is not drawn or delivered to unintended areas.  Most gaps can be sealed with a caulking gun and air duct sealant purchased from your local hardware store.  If the gap or damage is too large, contact an HVAC contractor.

Perform Routine HVAC Maintenance

Contract an HVAC contractor to provide routine maintenance on your heating and cooling system.  Routine maintenance will ensure that your system is running at its peak efficiency, and will prevent debris caused from mechanical neglect.

Limit Dust Indoors

The best way to limit dust in indoor air is to reduce the amount of dust you have indoors. Dust hard surfaces frequently. Use a vacuum cleaner with a good filter and weekly vacuum all carpets and fabric furniture. Wash bedding, pets, and pet bedding, every week. Limit indoor activities that create dust and never smoke indoors.