(This is part of an ongoing series where we will post answers to the most frequently asked questions we receive from our customers.)

We get this question all the time.  Which way should the arrow be pointing in when I install my Honeywell air filter in the air cleaner cabinet.  Well, the most direct answer is: In the direction of the air flow.  Simple enough, right?  The next question is always...well, how can I tell which way the air is flowing?  No problem, lets get down to it.  Your Honeywell air cleaner will always be installed on the return side of your system (air handler/heat pump, air handler/air conditioner, furnace, etc.)  If it is not then you have a big problem.  So lets assume your air cleaner is installed correctly.  Your system has a return side and a supply side for air distribution to and from your home.  Your ducts or the metal tubing is what allows for that air flow.  When operational, your heating and cooling system uses a fan motor to pressurize the duct system.  This has the effect of pushing air from your indoor unit through the duct work and depositing it at the supply register locations in your home (usually small rectangular or circular metal grills in the floor or ceiling).  This is referred to as the supply side.  It also has the effect of pulling or sucking air from your home back to the unit through separate and distinct duct work.  These grills that suck the air back are usually much larger than supply registers and are typically found in the walls or ceilings. This is referred to as the return side.  It is on the return side that your air cleaner is installed.  And as the air returns from your home it is filtered and then passes through your unit, conditioned and pushed into your living space as warm or cool air.  So that arrow on your filter should always be pointed towards or in the direction of your indoor unit.