Home Climate: Forced Air



Punch! Home Design Software



Forced-air systems are relatively inexpensive to purchase and easy to maintain, making them one of the most popular types of whole- house heating. Because their design includes air ducts throughout the house, you have the option to add whole-house air-conditioning, humidification and air cleaning to the system. A forced-air system contains five main elements: a furnace, a net work of distribution ducts, registers on walls or floors, an exhaust flue and a thermostat. A motor-powered blower circulates air through the system. A few old furnaces still use gravity circulation, which relies on the natural convection created by the buoyancy of hot air and the fact that cold air falls. These systems have larger ducts and no blower.

Homes with ductwork can leak noticeably more air and require more heating and cooling energy than homes without ductwork. The reason is that forced air creates pres sure differences within the house that can draw in outside air, force air out through cracks in the house or pull outside air in through cracks in the house, all of which waste heat.









To make sure your warm-air sys tem works efficiently, clean or replace the filter regularly and follow the furnace tune-up steps on the following pages. Also, be sure your system has enough return ducts—at least one per level. In addition, seal all seams in duct work, and insulate ducts in unheated spaces. For improved comfort, adjust dampers and registers to balance heat distribution. Some furnaces and thermostats allow you to run the blower constantly at a low speed. It costs more for the electricity to run the blower, but your house will be more comfortable and evenly heated, and your burner may run less.

How a furnace works: Components of a furnace (as shown in image above): To supply plenum, Gas line, Distribution duct, Return or cold-air duct, Power switch, Burner, Filter, Blower, Combustion chamber, Heat exchanger.

Above:

How a furnace works. The thermostat sends a signal to the burner located inside the combustion chamber which heats the outside of the heat exchanger. When the heat exchanger gets hot, the blower starts and pulls cool air into cold-air registers, through the cold-air return ducts, to the furnace. The return air goes through a filter to keep the blower clean. The air then passes through the inside of the heat exchanger, where it's warmed, safe from the burner combustion gases, which exit through the exhaust flue. Warm air is carried through the supply plenum and distribution ducts to warm-air supply registers in rooms.

Components of a furnace (as shown in image above): To supply plenum, Gas line, Distribution duct, Return or cold-air duct, Power switch, Burner, Filter, Blower, Combustion chamber, Heat exchanger.
continued...

  Shop for hand tools, power toools, hand tools and equipment.

Special Prices

Challenger Floor Furnace 75000 BTUs

Challenger Floor Furnace 75000 BTUs

∙ 10-year warranty for combustion chamber
∙ 100% safety pilot
∙ Wall thermostat
∙ Pyrex viewing window
∙ Draft diverter to prevent pilot outtage
∙ No electricity required
∙ Manual spark igniter

The COZY Challenger provides warm even heat all winter long through the natural convection of circulating warm air. COZY's scientific design assures a high volume air exchange (as much as three to five times each hour), guaranteeing uniform temperatures from floor to ceiling. The wall thermostat provides maximum comfort and convenience - set it and forget it!

The COZY Challenger features a factory mounted control with built-in pressure regulator and 100% safety pilot. All controls are millivolt/self-energizing, and require no electricity to operate; therefore, there is no need to worry about losing heat during a power failure!

The COZY Challenger occupies no room space and is easily installed between floor joists. The four models are available in four sizes to fit virtually any application. The heavy-duty steel baked-enamel floor register blends perfectly with any flooring composition - hardwood, carpet, or tile!

The Safety Limit Control on a Cozy Furnace offers you two settings to assure proper performance in any winter weather.

Cozy Value Features:
∙ NARROW WIDTH 30,000 BTU MODEL - Installs between a standard 16" center joist without cutting the joist.
∙ CONTINUOUS-SEAM WELDED COMBUSTION CHAMBER - constructed of heavy 18 gauge steel maximizes heat transfer. Warranted for 10 years.
∙ INNER JACKET is suspended with "U" type interlocking brackets and is easily removed for cleaning.
∙ JET TUBE BURNERS are durably constructed of aluminized steel and provide excellent flame characteristics for both Natural and L.P./gas. Slotted-port design eliminates ignition and extinction noise.
∙ 100% SAFETY PILOT/BUILT-IN PRESSURE REGULATOR completely stops the flow of gas in the event pilot flame is extinguished. The built in pressure regulator protects against line pressure surge.
∙ LOW BTU PILOT is durably constructed of stainless steel and provides maximum efficiency during standby.
∙ SAFETY LIMIT CONTROL maintains the lowest possible grill temperature consistent with heating required. Also cycles unit off in the event grill is blocked by a rug or furniture.
∙ WALL THERMOSTAT is standard on all models and provides maximum comfort and ease of operation.
∙ PYREX VISION CAP provides quick, safe visual check of burner and pilot operation.
∙ DRAFT DIVERTER is standard on all units and prevents pilot and burner outage due to downdraft.
∙ MILLIVOLT CONTROL ASSEMBLY - means no electricity is required to operate the unit. Heat is provided - even during a power failure!
∙ MATCHLESS SPARK IGNITION - eliminates the need f




BoAir Furnace and Air Cleaners Filter

BoAir Furnace and Air Cleaners Filter

Furnace filters and electrostatic air filters that are permanent and washable. Many sizes available.




14,000 BTU Natural Gas Direct-Vent Furnace with Wall or Cabinet-Mounted Thermostat

14,000 BTU Natural Gas Direct-Vent Furnace with Wall or Cabinet-Mounted Thermostat

Attractive styling, economical and safe heating comfort with this popular home furnace. Compact, space saving direct-vent heaters feature low cost installation and come equipped with all vent material. Heat only the room you're in while saving fuel costs in unused areas. This furnace's design features a sealed combustion chamber, making it great for garage or workshop heating. No electricity required, great during power outages. It is direct vented with a "Matchless" pilot igniter, automatic thermostat and safety controls.




Filtrete Ultra Allergen Reduction Furnace Filter 20 x 25 6 Per Carton

Filtrete Ultra Allergen Reduction Furnace Filter 20 x 25 6 Per Carton

Filtrete Ultra Allergen Reduction Furnace Filter 20 x 25 6 Per Carton




Monterey Top-Vent Wall Furnace, 50,000 Btu, Natural Gas with Wall or Cabinet-Mounted Thermostat

Monterey Top-Vent Wall Furnace, 50,000 Btu, Natural Gas with Wall or Cabinet-Mounted Thermostat

Select from the leader in combining high-efficiency home comfort with lower heating costs. Easy recessed or surface-mounted installation in homes, schools, cabins, apartments, offices and shops. Great during power outages, no electricity required. Patented, side-relief vent design reduces flue gas temperatures and also reduces operating costs. It is top vented and equipped with an automatic thermostat, safety controls, "matchless" pilot igniter and long-life ceramic-coated combustion chamber.


Learn how to weatherproof your home at homedepot.com  • BEST PRICES on Energy-saving Wood Stoves
A High-efficiency Furnace

High-efficiency Furnaces

Top-of-the-line furnace models can operate at very high levels of efficiency -- 95 percent or more. Their design features a second heat exchanger to draw usable heat from the exhaust gases. The cooler exhaust gas can then be routed through a small vent, often of PVC pipe, through an outside wall -- no conventional chimney is required. They also have a sealed combustion chamber and draw air from the outside, rather than inside. The downside is that the initial cost is greater and extra water-condensate from the exhaust must be piped or pumped to a drain.


Updated: Wednesday, June 22, 2016 14:01 PST