INDIANAPOLIS – We’ve all heard that you’re supposed to inspect and likely change your air filter in your furnace at the recommended times.  So what is the first step?  First thing is to turn down your thermostat so the furnace turns off.  Then to make sure it won’t turn back on while changing the filter, turn off the furnace. There is generally a switch located on the furnace.  If you can’t find that, you can always turn off the breaker for the furnace.

The next step is to locate the filter on the furnace.  It’s generally behind a metal flap near the bottom of the furnace.  Most filter holders are labeled and even have arrows drawn on them to show the direction of airflow, which is key to know when replacing the filter.  Open the flap, read the dimensions of the filter already inside.  Go to the store or order that same size replacement filter online.  Make sure the quality of filter is one the manufacturer recommends.  

Then slide out the old filter and slide in a new one, in the direction indicated by the arrows.  The arrows on the filter will line up with the airflow of the cold air return and furnace.  Most of the time, all you have to do is put the new one in, the same way the old one was taken out.  After replacing the filter, turn your furnace back on.

How often should you change filter?

The next question most homeowners have is how often should you change your filter?  That depends on the type and size of the furnace and filter.

“For a larger 4 or 5 inch filter, you should probably change it every 5 or 6 months.  For a one inch pleated filter, probably every 3 months and your standard one inch filter, we would suggest changing those out once a month,” said Ed Kittle, operations manager for Howald Heating AC and Plumbing

What happens when you DON’T change your filter?

How important are filters?  Here is an example of what happened when someone didn’t use a filter at all. The heat exchanger out of a 3-year-old furnace was destroyed.  The coil was completely plugged up, creating multiple cracks.  That’s an extreme case, but the same thing can happen with clogged air filters.  A furnace needs to be able to intake air and breathe or it will quickly overheat and become damaged.

Don’t forget about the humidifier pad

Now that you know the importance of filters, have you ever had this happen when checking yours?  

My filter wasn’t even a month old, but when I went down to the basement one morning, I noticed there was water all around the furnace and the filter was soaking wet.  The reason had nothing to do with the furnace or the filter, but the humidifier pad, which also needs to be checked regularly.  It had become brittle and was so crusty from hard water that the pad had collapsed inside its plastic frame.  That allowed the water to pour down into the cold air return.  It should have been slowly dripping onto the humidifier pad to deliver humidity to the entire house.  

The cold air return is connected to the air filter, so it was sucking up air into the filter and a lot of water.  That meant there was a ruined filter and a ruined humidifier pad all at once.  The moral of the story, check the humidifier pad often if you have one.

To get to the humidifier pad, open the lid.  They are all different.  Mine was held on by a bolt, which you just turn.  Sometimes they require a screwdriver.  Mine was rusted on, but eventually I got it removed.  Most owners manuals show which type of replacement honeycomb style pads will work for your specific filter.  If you don’t have the manual, just google the model number of your humidifier, to find the correct replacement pads. 

Follow the instructions to remove the pad and put a new one in.  It’s generally just a matter of removing the top plastic bracket to slide out the old pad and slide a new one in.  Put the plastic top piece back on, after sliding in the pad.  The plastic bracket is generally connected to the water tube that feeds the honeycomb filter.  Then reinstall in the humidifier lid or housing and tighten. 

You can also have a furnace technician do most of this for you in a matter of minutes when they are already servicing your furnace.  It’s highly recommended to get a semi annual service to prevent problems.  Those plans will generally cover the service on your furnace and your exterior air conditioning.  Shop around for a reputable company that also have good prices.