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Posted by udarrell on July 29, 2006, 11:59 am
use_a_hammer@yahoo.com wrote:
>Is there a difference in the airflow between a Merv 7 -vs- Merv 11?
>
>These are the filters http://www.airguard.com/pleated.html I'm talking
>about in case brand makes any difference. I'm looking at the "DP Max"
>(merv 7) vs "Powerguard" (merv11)
>
>I see they have an efficiency rating, whatever that is. Does a Merv 11
>restrict more air than a Merv 7?
>
>
A higher static pressure will restrict more of the airflow.
>I'm looking for good airflow and a "HEPA type" filter combined.
>
>
You need to know the air velocity through the filter then look at the
initial resistance or pressure drop.
Hopefully you return air & filter grille were sized so you have 300-FPM
rather than 500-fpm or more!
One for example has .26 pres. drop at 300-fpm but .54 pres. resistance
at 50-fpm air velocity through the filter!
Most residential blower systems are rated at .50-ESP External Static
Pressure.
When the filter begins loading at 500-fpm you will have a big drop off
in airflow!
- udarrell
--
Air Conditioning's Affordable Path to the "Human Comfort Zone Goal"
http://www.udarrell.com/air-conditioning-total-heat-enthalpy-latent-heat.html
For HVAC Techs:
http://www.udarrell.com/ac-trouble-shooting-superheat-subcooling.html
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