Chicago HVAC News

A maze of heating and air conditioning ducts runs inside the walls and floors of 80 percent of American homes. As the supply ducts blow air into the rooms, return ducts inhale airborne dust and suck it back into the blower. Add moisture to this mixture and you’ve got a breeding ground for allergy-inducing molds, mites and bacteria. Many filters commonly used today can’t keep dust and debris from streaming into the air and over time sizable accumulations can form — think dust bunnies, but bigger.

To find out if your ducts need cleaning, pull off some supply and return registers and take a look. If a new furnace is being installed, you should probably invest in a duct cleaning at the same time, because chances are the new blower will be more powerful than the old one and will stir up a lot of dust. Professional duct cleaners tout such benefits as cleaner indoor air, longer equipment life and lower energy costs. Clean HVAC systems can also perform more efficiently, which may decrease energy costs, and last longer, reducing the need for costly replacement or repairs. Cleaning has little effect on air quality, primarily because most indoor dust drifts in from the outdoors. But it does get rid of the stuff that mold and bacteria grow on, and that means less of it gets airborne, a boon to allergy sufferers.

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Most houses with forced-air furnaces have a standard furnace filter made from loosely woven spun-glass fibers designed to keep it and its ductwork clean. Unfortunately, they don’t improve indoor air quality. That takes a media filter, which sits in between the main return duct and the blower cabinet. Made of a deeply pleated, paper-like material, media filters are at least seven times better than a standard filter at removing dust and other particles. An upgrade to a pleated media filter will cleanse the air of everything from insecticide dust to flu viruses.

Compressed, media filters are usually no wider than six inches, but the pleated material can cover up to 75 square feet when stretched out. This increased area of filtration accounts for the filter’s long life, which can exceed two years. The only drawback to a media filter is its tight weave, which can restrict a furnace’s ability to blow air through the house. To insure a steady, strong airflow through the house, choose a filter that matches your blower’s capacity.

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Tuning up the distribution side of a forced-air system starts with the blower. The axle should be lubricated; blades cleaned and lower motor checked to insure the unit isn’t being overloaded. The fan belt should be adjusted so it deflects no more than an inch when pressed. Every accessible joint in the ductwork should be sealed with mastic or UL-approved duct tapes. Any ducts that run outside the heated space should be insulated. On a hot-water system, the expansion tank should be drained, the circulating pump cleaned and lubricated and air bled out of the radiators.

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Fueled by gas, electricity, or oil, a forced-air distribution system is just what the name implies. Air is forced from the furnace through ducts to registers in various rooms. Besides warming the air, the blower system that distributes the warmed air also returns the cold air to the furnace so it can be rewarmed and distributed to the rooms again.

A forced-air system is also efficient for distributing cool air from a central air conditioner with the same ducts, registers, and blower. There is little that can go wrong with a forced-air system. The big problems typically include noise and blockage of airflow, usually caused by dirt or by furniture or draperies blocking the registers. Forced-air systems should be cleaned and maintained regularly. Floor registers are slip-fit into ducts or are held by retaining screws on the frame of the register. Wall and ceiling registers are also held in place by retaining screws on the frame of the register. Duct joints are usually slip-fit and held with sheet-metal screws or duct tape. The ducts are supported by wire or metal strap hangers nailed or screwed to wooden framing members such as studs and rafters. All of these parts are easy to disassemble. Lay them out in order as you work so you’ll be able to reassemble them properly.

A problem can arise with this type of system in which the temperature of different rooms varies widely.

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Most of us take heating and cooling for granted. We expect our heating systems to keep us warm during the winter, and we depend on air-conditioning to keep us cool during the summer.

When the house is cold in winter or hot in summer, the natural reaction is to call for professional service. Fortunately, there is an alternative. You can cut service costs drastically and keep your heating and cooling systems working efficiently by doing some maintenance and quick fixes yourself. But first, it’s important to know how the basics of how heating and cooling systems function.How Heating and Cooling Systems Work

All climate-control devices or systems have three basic components: a source of warmed or cooled air, a means of distributing the air to the rooms being heated or cooled, and a control used to regulate the system (e.g., thermostat). The sources of warm air, such as a furnace, and cool air, such as an air conditioner, in a house often use the same distribution and control systems. If your house has central air conditioning, cool air probably flows through the same ducts that heat does and is regulated by the same thermostat. When a heating or cooling system malfunctions, any of these three basic components may be causing the problem.

Both heating and air conditioning work on the principle that heat always moves from a warm object to a cooler one, just as water flows from a higher to a lower level. Furnaces and heaters put heat into the air to make your home warmer; air conditioners remove heat to make your home cooler.

All heating and cooling units burn fuel. Air conditioners use electricity. Most home heating systems use gas or fuel oil; other systems use electricity. The heat pump — an electrically powered climate control unit — both heats and cools air. In summer it extracts heat from the air inside your home. In winter it pulls heat from the air outside and uses this heat to warm the air inside.

When the furnace is turned on, it consumes the fuel that powers it, whether it be gas, oil, or electricity. As fuel is burned, heat is produced and channeled to the living areas of your home through ducts, pipes, or wires and then is blown out of registers, radiators, or heating panels. Older systems use the heat they produce to heat water, which in turn heats the air in your home. These systems use a boiler to store and heat the water supply, which is then circulated as hot water through pipes embedded in the wall, floor, or ceiling.

When an air conditioner is turned on, electrical power is used to cool a gas in a coil to its liquid state. Warm air in your home is cooled by contact with the cooling coil, and this cooled air is channeled to the rooms of your home through ducts and out registers or — in the case of room air conditioners — directly from the unit itself.

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We replaced our old heat pump with a new energy efficient model recently. The system uses the original ducts. When we start our system after it has been idle for several days we notice what seems to be a mildew smell coming from the ducts. After a while the odor goes away. The old heat pump didn’t seem to do this.

I have sprayed disinfectant into the air return and into the area around the condensing unit with not much success. We have owned the home - built in the 1980s - for four years built and, as far as I know, the ducts have never been cleaned. We lived in our other house for years and never had the ducts cleaned.

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Most people are now aware that indoor air pollution is an issue of growing concern and increased visibility. Many companies are marketing products and services intended to improve the quality of your indoor air. You have probably seen an advertisement, received a coupon in the mail, or been approached directly by a company offering to clean your air ducts as a means of improving your home’s indoor air quality. These services typically — but not always — range in cost from $450 to $1,000 per heating and cooling system, depending on the services offered, the size of the system to be cleaned, system accessibility, climatic region, and level of contamination.

Duct cleaning generally refers to the cleaning of various heating and cooling system components of forced air systems, including the supply and return air ducts and registers, grilles and diffusers, heat exchangers heating and cooling coils, condensate drain pans (drip pans), fan motor and fan housing, and the air handling unit housing.

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