First item to check is to make sure your filter is properly sized for your furnace. Ensure that the filter completely fills the holding area, with gaps at top, bottom or sides. Also the filter should be thick enough to seal off any avenues for air to bypass the filter. Another item to check is your owners manual for the furnace and check that you have the right style of filter for your furnace. Some people buy universal re-usable filters that might provide too much resistance for the modern high-efficiency furnaces used today. If no manual is available check on the internet for manufactures site and look up specifications for model of furnace you have. If no specifications are available, send them an email, most companies gladly provide information on requests from customers. Clean or replace your disposable furnace filter periodically during the winter--check the filter monthly. Brush and vacuum the heat exchanger surfaces every year, if recommended by your owner's manual. Before the heating season, clean the blower blades and seal any air leaks in ducts with several wraps of duct tape.

A little maintenance goes a long way toward keeping your forced-air equipment working properly. Start by cleaning or replacing the filter. With forced-air furnace systems, air returning to the furnace's blower first passes through an air filter designed to catch dust and debris and help clean the air before it's recycled to your home. On new homes, check all your ducts by removing grills and vacuuming any debris that you can reach. If extremely dirty, notify builder and have him clean the ducts. This is only possible on new construction.

A good furnace filter can help reduce allergens but isn't designed to significantly improve air quality in your home. For that, you'll need a special air filter (talk to a heating specialist about this).

When typical filters become clogged with debris, they cut down on a furnace's efficiency and, over time, can cause parts to wear out faster. Change filters quarterly or sooner if they look dirty. Pleated fabric filters are a good, inexpensive choice for reducing dust and allergens.

Here's how to change a replaceable filter:

1) Turn off the power to the unit.

2) Look for the door or panel that conceals the blower; sometimes this is marked "Filter." Lift this door or panel off of its holding hooks or unscrew its retaining screws to remove it.

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3) Standard filters are mounted next to or under the blower motor. Newer furnaces have the filter installed on exterior of furnace on supply side. A good installation will have a metal cover over side of filter to prevent air leakage. Remove cover and slide the filter out along its tracks. Check to see whether it is a disposable filter or intended to be cleaned and replaced--this should be marked on the filter's edge, along with directions for cleaning if applicable. If it's a disposable filter, its size will probably be printed on the frame's edge also. Make a note of its size.

4) Buy a replacement and slide it back into place, noting that arrows stamped on the side indicate the proper direction of airflow; be sure you face these in the proper direction. If your smoke detectors or carbon-monoxide detectors start going off after cleaning your filter, you have installed the filter facing the wrong direction. Remove and reverse filter, this will resolve your detector alarm problem. More home improvement articles are available on diy.napoleon.cc website.