View Full Version : MERV rating vs airflow
01-09-2011, 01:26 PM
I recently replaced my old EAC with a Merv 8 4" Honeywell pleated media filter. Is there any data out there to determine the comparative airflow restriction between these two filters? I know that the Merv rating indicates particle size capture but I couldn't find any information related to airflow restriction.
Is Merv 8 good enough to protect the HVAC equipment without compromising performance?
01-09-2011, 02:34 PM
MERV 8 is ok.
01-10-2011, 09:37 AM
See attached for info. Not much difference between the two types of filters when they are clean. When the 4" filter gets dirty the pressure drop goes up but do not let it go to 1" before you change. I like the electronic filter myself.
Hope this helps
01-10-2011, 10:41 AM
The Honeywell filter I'm using is 4 3/8" thick. It says 4 inches on the box but other manufacturers call that a 5 " filter. Not sure I understand what you mean by "not letting it go to 1" ". Did you mean don't let it get 3" of dirt in it before changing it? Since this is new to me, I plan on monitoring the filter periodically and changing it well before it gets really dirty. I always keep on top of things like this. I switched from the EAC to this media because I have washed the electronic cells every month for 13 years and I'm sick of doing it! I must admit that the evaporator coil on the 13 year old furnace I just had replaced was amazingly clean. I'm hoping that the media filter will do just as good a job or better. Thanks for your response.
01-10-2011, 11:07 AM
The 1" stated refers to total external static pressures (tesp). This is a measurement of the external pressured acting upon your blower and directly affects airflow. This can be measured by a technician or by equipment permantly installed. Equipment is generally rated at between 0.5 & 0.8" ac (water column). At 1" the system would exceed recommended tesp and airflow delivery would suffer. Here is some info if you are interested:
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