Can you tell me why it is so important to install the
air conditioner filter in a certain direction? What
harm, if any, does it do if it’s backwards? My husband
always puts it in backwards.
Now that we’re tuning up our furnaces for winter, let
me assure you that HVAC companies are not just blowing
hot air when they implore you to install filters
fact, they warn that constantly putting them in
backwards like your apparently worser half could
conceivably result in your system blowing no air at all.
the two sides of an air filter might look the same, they
are not. If you’d examine them with a magnifying
glass, you’d find that one side is more porous than
the other. This allows the filter to effectively trap
airborne particles while also minimizing the slowdown of
airflow through your system.
installing your filter backwards, air will have a harder
time flowing through the filter and your air handler
will have to work harder to make up for the loss of
airflow. This could lead to higher utility bills and
possibly damage your furnace or air conditioner. And the
last thing you want is your HVAC system conking out on a
zero-degree night or 105-degree day.
be sure to look for the arrows that are printed on the
sides of the filters because they show you which way the
filters are supposed to be installed. That arrow must
always face toward the furnace and away from the return
duct that carries the air in need of heating or cooling.
Forced air furnaces recirculate air throughout a home,
blowing air (cooled or heated) out while pulling spent
air back in for another cycle.
make the chore next to automatic, you might consider
grabbing a permanent marker and drawing the arrow in its
proper direction on the actual furnace housing or
ductwork. That way you easily can make sure the two
arrows match the next time you change your filter. Dirty
filters are also a drag on the system, so don’t forget
to change them at intervals you’ll find recommended on
my word picture has left you more confused than ever,
you might want to watch a short video at