Ductwork

Duct Leakage

One of the most important systems in your home, though it's hidden beneath your feet and over your head, may be wasting a lot of your energy dollars. Your home's duct system, a branching network of tubes in the walls, floors, and ceilings, carries the air from your home's furnace and central air conditioner to each room. Ducts are made of sheet metal, fiber glass, or other materials.

Unfortunately, many duct systems are poorly insulated or not insulated properly. Ducts that leak heated air into unheated spaces can add hundreds of dollars a year to your heating and cooling bills. Insulating ducts that are in unconditioned spaces is usually very cost effective. If you are buying a new duct system, consider one that comes with insulation already installed.

Ducts - Out of Sight, Out of Mind

The unsealed ducts in your attics and crawl spaces lose air—uninsulated ducts lose heat, wasting energy and money.

Sealing your ducts to prevent leaks is even more important if the ducts are located in an unconditioned area such as an attic or vented crawl space. If the supply ducts are leaking, heated or cooled air can be forced out unsealed joints and lost. In addition, unconditioned air can also be drawn into return ducts through unsealed joints. In the summer, hot attic air can be drawn in, increasing the load on the air conditioner. In the winter, your furnace will have to work longer to keep your house comfortable. Either way, your energy losses cost you money.

Duct Cleaning

Should you get your house ducts cleaned?

A hot air furnace heats and distributes air through its ducting system.The ducts are usually made of sheet metal and are most obvious in your basement, where they hang from the floor joists.The return, or cold air, ducts bring air to the furnace, usually collecting it centrally in the house. The return air trunk duct is the big rectangular duct along the basement ceiling that enters the bottom of the furnace. The supply, or warm air, ducting usually exits from the top of the furnace. It starts with a trunk duct on the basement ceiling.The individual supply ducts, in round or smaller rectangular sheet metal, branch off the trunk duct and go to each room, where they terminate in a floor or wall register. Over time, dust and debris will collect in these ducts, particularly in the return air ducts.You may be wondering whether it would be worthwhile to have these ducts cleaned.

Duct cleaning is a major industry. As a homeowner, you may be regularly solicited to have your heating ducts cleaned on a regular basis. Claims are made that duct cleaning will:

• provide you with better indoor air quality (or IAQ),
• reduce the presence of house molds and allergens,
• get rid of house dust,
• result in more airflow and better delivery of warm air, and/or
• reduce energy costs.

What can duct cleaning do for you?

Duct cleaning can clean your ducts. Thorough, professional duct cleaning will remove dust and debris - pet hair, paper clips, children's toys, and whatever else might collect down there. Ideally, the inside surface will be shiny and bright after cleaning. Duct cleaning may be justifiable to you personally for that very reason: you may not want to have your house air circulated through a duct passage that is not as clean as the rest of the house. However, duct cleaning will not usually change the quality of the air you breathe, nor will it significantly affect airflows or heating costs.

In the 1990s, duct cleaning research conducted by Canada Mortgage and Housing Corporation (CMHC)1,2 and the US Environmental Protection Agency (EPA)3 tested house and duct performance before and after cleaning. Researchers observed little or no discernible differences in the concentrations of house airborne particles or in duct airflows due to duct cleaning. This is because ducts are just metal passages.They cannot create dust. Most household dust comes from outdoor dust that has been tracked in or blows through windows or other openings. Dust is also created by human skin and hair shedding, pet debris, fibres from carpets, clothes, bedding, hobbies etc. In fact, as you walk around in your house you raise a small cloud of dust particles wherever you go. Dust will be present in one form or another whether you have clean ducts or not.

Householders often expect an efficient furnace filter will remove airborne dust. CMHC has tested the effectiveness of furnace filters in reducing household dust. While some very good filters effectively clean the air in the ducts, they do not create a dust-free environment in your house because of all the dust sources mentioned above. A good filter will help keep your air-conditioning coil, furnace heat exchanger, and supply ducts from accumulating circulated dust.

When does duct cleaning make sense?

There are several situations when duct cleaning could make sense (although there is little research data to support this).

• If you have a problem with water in your ducts, this may result in mold growth in the duct. In this situation, solve the water problem first, clean and disinfect the ducts where mold growth has occurred, and have the rest of the ducting system cleaned as well. In some cases, it may be necessary or more cost effective to simply replace the affected duct areas.
• If you are moving into a newly constructed house, and have doubts about the diligence of the construction crew, duct cleaning can be useful. Drywall dust, fibreglass pieces, and sawdust have no place in ducts. Duct cleaning will also catch the odd occurrence where lunch bags or soft drink cans have fallen or been swept into ducting. For similar reasons, duct cleaning may be advisable for older houses following major renovations.
• If you are having trouble with furnace airflow, a duct cleaning could reveal significant blockages. Have the ducts cleaned before you embark on more expensive duct replacement or rerouting to solve an airflow problem. Cleaning of furnace and air conditioning components (e.g. furnace fan blower, air conditioning coil, humidifier, furnace heat exchanger, etc.) has been shown to make some difference in duct air flow.
• If you look in the return air registers and see an accumulation of debris in the duct below, you may want to have it removed. CMHC research showed that return air ducts, which are relatively big and have slow moving air, are generally far dirtier than the supply ducts.You should be able to accomplish much of the return air duct cleaning with a household vacuum cleaner after removing the register grill. For example, households with hairy pets or forgetful young children may find it necessary to inspect their return air ducts more frequently. Do not expect any difference in airflow or house air quality after this cleaning.