The Importance of HVAC Filter Changes

Changing furnace and return air filters is critical to the proper performance of your HVAC system, not to mention your home’s air quality.

Air filters are an often under-appreciated part of a central HVAC system. They don’t just filter out bits of pollen and dust that would otherwise circulate through the home and lower indoors air quality. They also provide a first line of defense against larger objects. But if you don’t change your air filter regularly, it can turn against you.

All the air handled by the HVAC system passes through the air filter at one point or another. As the filter catches more and more of the natural particulate pollution of your home – dust, mold and fungal spores, pet dander, fabric fibers, etc. – the fine mesh through which air passes becomes denser. This means that if you don’t change your air filter regularly, air can’t pass through as readily.

Some results for having a clogged air filter include but not limited to:

  • Clogs generate increased energy consumption –  Because the system relies on the constant recirculation of air, the performance of your heating and cooling system’s blower fan can have a big impact on your home’s energy consumption. The harder this fan has to work to draw air throughout your home, the higher your energy bills will be. In fact, a clogged filter can use 15% more energy, according to the Department of Energy. This inefficiency increases quickly as the filter becomes more and more clogged, or until the filter is serviced.

  • Clogs cause frozen evaporator coils – If your air filter clogs during the summer cooling season, this can cause the evaporator or cooling coil to freeze up because not enough air is moving past the coil to dissipate the condensation that is normally produced during the cooling process.

  • Clogs lead to inadequate heating/cooling – Blower fans push the air through the filter. If the filter becomes too clogged with dust, dander and debris, then the blower has to strain harder to pass the air through a clogged filter. With reduced airflow you can experience hot and cold spots in your home, and it could be difficult to reach your desired indoor temperature levels.

  • Clogs contribute to unhealthy air – A clogged air filter will allow all that dust and debris that should be filtered out to be re-circulated back into your home. This can cause chronic allergies and especially be dangerous for people with asthma or other respiratory conditions.

  • Clogs lead to furnace failure – Likely the costliest result of an improperly changed air filter may be the internal damage it deals to your central air conditioning and heating system.

Overheated Clothes Dryers Can Cause Fires

CPSC Document # 5022

 Updated June 2003 

The U.S. Consumer Product Safety Commission estimates that in 1998, clothes dryers were associated with 15,600 fires, which resulted in 20 deaths and 370 injuries. 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.

 To prevent fires you can:

  • Clean the lint screen/filter before or after drying each load of clothes. If clothing is still damp at the end of a typical drying cycle or drying requires longer times than normal, this may be a sign that the lint screen or the exhaust duct is blocked.
  • Clean the dryer vent and exhaust duct periodically. Check the outside dryer vent while the dryer is operating to make sure exhaust air is escaping. If it is not, the vent or the exhaust duct may be blocked. To remove a blockage in the exhaust path, it may be necessary to disconnect the exhaust duct from the dryer. Remember to reconnect the ducting to the dryer and outside vent before using the dryer again.
  • Clean behind the dryer, where lint can build up. Have a qualified service person clean the interior of the dryer chassis periodically to minimize the amount of lint accumulation. Keep the area around the dryer clean and free of clutter.
  • Replace plastic or foil, accordion-type ducting material with rigid or corrugated semi-rigid metal duct. Most manufacturers specify the use of a rigid or corrugated semi-rigid metal duct, which provides maximum airflow. The 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.
  • Take special care when drying clothes that have been soiled with volatile chemicals such as gasoline, cooking oils, cleaning agents, or finishing oils and stains. If possible, wash the clothing more than once to minimize the amount of volatile chemicals on the clothes and, preferably, hang the clothes to dry. If using a dryer, use the lowest heat setting and a drying cycle that has a cool-down period at the end of the cycle. To prevent clothes from igniting after drying, do not leave the dried clothes in the dryer or piled in a laundry basket.


Carbon Monoxide Fact Sheet

Consumer Protection Safety Commission Document #4466


What is carbon monoxide (CO) and how is it produced in the home?

 CO is a colorless, odorless, toxic gas. It is produced by the incomplete combustion of solid, liquid and gaseous fuels. Appliances fueled with gas, oil, kerosene, or wood may produce CO. If such appliances are not installed, maintained, and used properly, CO may accumulate to dangerous levels.


What are the symptoms of CO poisoning and why are these symptoms particularly dangerous?

Breathing CO causes symptoms such as headaches, dizziness, and weakness in healthy people. CO also causes sleepiness, nausea, vomiting, confusion and disorientation. At very high levels, it causes loss of consciousness and death.

 This is particularly dangerous because CO effects often are not recognized. CO is odorless and some of the symptoms of CO poisoning are similar to the flu or other common illnesses.


Are some people more affected by exposure to CO than others?

 CO exposures especially affect unborn babies, infants, and people with anemia or a history of heart disease. Breathing low levels of the chemical can cause fatigue and increase chest pain in people with chronic heart disease.


How many people die from CO poisoning each year?

 In 1989, the most recent year for which statistics are available, thee were about 220 deaths from CO poisoning associated with gas-fired appliances, about 30 CO deaths associated with solid-fueled appliances (including charcoal grills), and about 45 CO deaths associated with liquid- fueled heaters.


How many people are poisoned from CO each year?

 Nearly 5,000 people in the United States are treated in hospital emergency rooms for CO poisoning; this number is believed to be an underestimate because many people with CO symptoms mistake the symptoms for the flu or are misdiagnosed and never get treated.


How can production of dangerous levels of CO be prevented?

 Dangerous levels of CO can be prevented by proper appliance maintenance, installation, and use:



A qualified service technician should check your home’s central and room heating appliances (including water heaters and gas dryers) annually. The technician should look at the electrical and mechanical components of appliances, such as thermostat controls and automatic safety devices.


Chimneys and flues should be checked for blockages, corrosion, and loose connections.

Individual appliances should be serviced regularly. Kerosene and gas space heaters (vented and unvented) should be cleaned and inspected to insure proper operation.

CPSC recommends finding a reputable service company in the phone book or asking your utility company to suggest a qualified service technician.


Proper installation is critical to the safe operation of combustion appliances. All new appliances have installation instructions that should be followed exactly. Local building codes should be followed as well.

 Vented appliances should be vented properly, according to manufacturer’s instructions.

Adequate combustion air should be provided to assure complete combustion.

All combustion appliances should be installed by professionals.


Appliance Use

Follow manufacturer’s directions for safe operation.

 Make sure the room where an unvented gas or kerosene space heater is used is well ventilated; doors leading to another room should be open to insure proper ventilation.

Never use an unvented combustion heater overnight or in a room where you are sleeping.


Are there signs that might indicate improper appliance operation?

 Yes, these are:

Decreasing hot water supply

Furnace unable to heat house or runs constantly

Sooting, especially on appliances

Unfamiliar or burning odor

Increased condensation inside windows


Are there visible signs that might indicate a CO problem? 

Yes, these are:

 Improper connections on vents and chimneys

Visible rust or stains on vents and chimneys

An appliance that makes unusual sounds or emits an unusual smell

An appliance that keeps shutting off (Many new appliances have safety components attached that prevent operation if an unsafe condition exists. If an appliance stops operating, it may be because a safety device is preventing a dangerous condition. Therefore, don’t try to operate an appliance that keeps shutting off; call a service person instead.)


Are there other ways to prevent CO poisoning?

Yes, these are: 

Never use a range or oven to heat the living areas of the home

Never use a charcoal grill or hibachi in the home

Never keep a car running in an attached garage


CO Detection

Can CO be detected?

 Yes, CO can be detected with CO detectors that meet the requirements of Underwriters Laboratories (UL) standard 2034. 

Since the toxic effect of CO is dependent upon both CO concentration and length of exposure, long-term exposure to a low concentration can produce effects similar to short term exposure to a high concentration. 

Detectors that meet the UL standard measure both high CO concentrations over short periods of time and low CO concentrations over long periods of time. The effects of CO can be cumulative over time 

Detectors sound an alarm before the level of CO in a person’s blood would become crippling 

Detectors that meet the UL 2034 standard currently cost between $35 and $80.


Where should the detector be installed?

CO gases distribute evenly and fairly quickly throughout the house; therefore, a CO detector should be installed on the wall or ceiling in sleeping area/s but outside individual bedrooms to alert occupants who are sleeping.


Aren’t there safety devices already on some appliances? And if so, why is a CO detector needed?

 Vent safety shut-off systems have been required on furnaces and vented heaters sine the late 1980s. They protect against blocked or disconnected vents or chimneys.

 Oxygen depletion sensors (ODS) have also been installed on unvented gas space heaters since the 1980s. ODS protect against the production of CO caused by insufficient oxygen for proper combustion.

 These devices (ODSs and vent safety shut-off systems) are not a substitute for regular professional servicing, and many older, potentially CO-producing appliances may not have such devices. Therefore, a CO detector is still important in any home as another line of defense.


Are there other CO detectors that are less expensive?

 There are inexpensive cardboard or plastic detectors that change color and do not sound an alarm and have a limited useful life. They require the occupant to look at the device to determine if CO is present. CO concentrations can build up rapidly while occupants are asleep, and these devices would not sound an alarm to wake them.


Consumer Protection Safety Commission’s Role

CPSC worked closely with UL to develop a safety standard for CO detectors (UL 2034).

CPSC embarked on an extensive public awareness campaign in 1993 to reach consumers and educate them about CO through the media. Activities included a message from President Clinton declaring the last week of September “CO Safety Awareness Week.” CPSC also developed stories for television, radio, and newspapers, as well as brochures and posters for consumers.

CPSC is proposing that the national model building code organizations include a provision for the installation of state of the art CO detectors in all new residential construction. The proposal calls for installation in sleeping areas, but outside individual bedrooms.

Under CPSC’s proposal, battery-operated units would be allowed only in existing homes, not new construction. Even homes with no permanently-installed fuel-burning appliances would have to install them because CO deaths have been associated with the use of portable kerosene heaters, wood-burning stoves, charcoal grills wrongly used indoors, and auto fumes from an attached garage.

CPSC staff is working with state and local code jurisdictions to incorporate CO detector requirements into state and local legislation.

CPSC is working with the National Fire Protection Association to develop a national installation standard.

CO Detector Requirements in the U.S.

On September 15, 1993, Chicago, IL became one of the first cities in the nation to adopt an ordinance requiring the installation of CO detectors that bear the mark of a nationally-recognized testing laboratory in all new single-family homes and in existing single-family residences that are being equipped with new oil or gas combustion furnaces.

Kingston, NY has approved a code to require the installation of CO detectors in multiple dwellings with four or more dwelling units.

Bel Air, TX requires CO detectors in some single-family dwellings.

The Recreational Vehicle Industry Association (RVIA) requires CO detectors in motor homes made after September 1, 1993. RVIA requires CO detectors in all recreational vehicles that are motorized and in towable recreational vehicles that have a generator or are prepped for a generator. RVIA’s membership includes approximately 90% of all U.S. recreational vehicle manufacturers.


Energy Savings

Allergy Help

Seer Ratings

R-22 Phase Out