A furnace's main job is to provide a building or structure with heat. They can be fired by gas, oil, or even wood. They heat air, which is circulated through a heating system and distributed within the building by a blower.

Direct Energy, a Houston-based service company, has a great description of how a furnace and air conditioner work together. It gives a complete picture of your systems and their main components. Check it out here. 

What do you need to do to keep your furnace running at its best?

• replace the air filter once a month
• if it's more than 3 years old, have a contractor conduct yearly inspections/maintenance.

If you have any questions about how your furnace is running, contact me.

-Rich

Check your drain line off the furnace for clogs. Clogs can be caused by bacteria growth. You can take the drain line off and clean it out with bleach.

-Rich

A majority of the time, it’s a dirty condenser, but check your filter first. If it is clogged up or dirty, replace it to see if that makes a difference in the sound. If the filter is really dirty, leave the AC unit off for approximately 15 minutes to make sure the A-coil did not freeze from the inability of air to blow through the unit. 

While you are waiting you can clean the condenser. In order to clean the condenser, turn the AC off at the thermostat, and go outside with your hose, not a power washer, and spray off the condenser for approximately 15 minutes until it is clean. That typically quiets the unit down. If this does not work, you likely need a service call.    

-Rich

For air conditioners and furnaces, filters should be changed once a month. For air purifiers, they usually need to be changed every six months, and require very specific filters. For air conditioners and furnaces, regular pleated filters work well. Don't buy the least or the most expensive filters, but something in the middle. Expect to pay $5-6 per filter. You can buy them in bulk to save money. Make sure they are the correct size.

-Rich