Just like your favorite car, your heating and cooling system needs a regular trip to the mechanic to keep it purring. Without regular servicing, heating and cooling systems burn more fuel and are more likely to break down. With the proper attention, they can keep you comfortable year-round.

Gas-fired furnaces need a yearly professional tune-up. Gas-fired equipment burns cleaner; it should be serviced every other year. A close inspection will uncover leaks, soot, rust, rot, corroded electrical contacts and frayed wires. In furnaces, the inspection should also cover the flue vent, ductwork, dampers, blower, registers, the gas line and the gas meter—as well as every part of the furnace itself.

Next, the system should be run through a full heating cycle to ensure that it has plenty of combustion air and chimney draft. Contractors can use specialty meters to check for sufficient draft and also test the air for carbon monoxide.

Finally, it's time for the down and dirty task of cleaning the burner and heat exchanger to remove soot and other gunk that can impede smooth operation. Indoor and outdoor coils should be cleaned, and the refrigerant pressure should be checked. Low pressure indicates a leak; to locate it, contractors pressurize a refrigerant system and search the system with an electronic leak detector.

The Low Blow

Tuning up the distribution side of a forced-air system starts with the blower. The axle should be lubricated, blades cleaned and blower motor checked to insure the unit isn't being overloaded. The fan belt (if one exists) 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 a UL-approved duct tapes. Any ducts that run outside the heated space should be insulated.

Turn It Up

While thermostats rarely fail outright, they can degrade over time as mechanical parts stick or lose their calibration. Older units will send faulty signals if they've been knocked out of level or have dirty switches. To recalibrate an older unit, use a wrench to adjust the nut on the back of the mercury switch until it turns the system on and, using a room thermometer, set it to the correct temperature. Modern electronic thermostats, sealed at the factory to keep out dust and grime, rarely need adjusting. However, whether your thermostat is old or young, the hole where the thermostat wire comes through the wall needs to be caulked or a draft could trick it into thinking the room is warmer or colder than it really is.

Humidifers

A neglected in-duct humidifier can breed mildew and bacteria, not to mention add too much moisture to a house. A common mistake with humidifiers is leaving them on after the heating season ends. Don't forget to pull the plug, shut the water valve and drain the unit. A unit with a water reservoir should be drained and cleaned with white vinegar, a mix of one part chlorine bleach to eight parts water or muriatic acid. Mist-type humidifiers also require regular cleaning to remove mineral deposits.

Filters

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 ensure a steady, strong air-flow through house, choose a filter that matches your blower's capacity.