MERV stands for Minimum Efficiency Reporting Value. MERV is a numerical value given to furnace filters in order to identify its filtering abilities. This is now an international industry standard set up by the committee that oversees the furnace filter industry. This standard is used for determining a furnace filter's ability to capture and hold dirt and dust in specific size ranges. Some furnace filter manufacturers such as 3M use their own rating system, which is not approved as an industry standard. Average Particle Size Efficiency in Microns 3.0 - 10.0: less then 20% 3.0 - 10.0: 49.9% 3.0 - 10.0: 84.9% 1.0 - 3.0: 50% - 64.9%3.0 - 10.0: 85% or greater 1.0 - 3.0: 80% - 89.9%3.0 - 10.0: 90% or greater 0.3 - 1.0: 75% - 84.9%1.0 - 3.0: 90% or greater 0.3 - 1.0: 75% or greater A human hair is 20-40 microns in size. MERV ratings are determined by adding particles of varying sizes (1-12) into a controlled testing environment.

The particles are added upstream of the test filter and a laser particle counter samples the air before it enters the furnace filter and after it leaves the furnace filter. The two particle counts are compared to calculate the Particle Size Efficiency of the tested furnace filter. Once this is determined, a MERV Parameters chart is used to determine the MERV rating. MERV ratings range from 1 - 16 and measurements are in microns. Some of the common particles related to MERV ratings are pet dander, insecticide dust, smog, dust, viruses, wood, tobacco smoke, spores, bacteria and pollen.ac unit best Some of the most common furnace filters found in residential use only have a MERV rating of 1 to 4.new ac unit not working Often times these furnace filters are not assigned a MERV rating.how much a new ac unit cost

These are typically disposable panel type filters and do not do a good job of filtering the air because they will not stop particles smaller than 10 microns. MERV 5 to 8 rated furnace filters are a better choice and are more commonly found in commercial applications. These furnace filters will collect particles as small as 3 microns and are a good choice for homeowners. Furnace filters with a MERV rating of 9 to 12 are used in commercial and industrial applications and will stop particles in the 1 to 3 micron range. These furnace filters are a great choice for homeowners who want the best dust control possible. When using furnace filters in this group it is important to change them on a regular schedule because if they become heavily loaded with dust they can have a negative impact on equipment performance. What do filter rating scores indicate? The furnace filter performance rating system can be used to compare one furnace filter to another and describes a filter's ability to remove particles from the air.

The HVAC, (Heating, Ventilating and Air Conditioning) industry uses ASHRAE 52.2 testing, which assigns a Minimum Efficiency Reporting Value (MERV). A larger MERV number means better filtration.All residential air conditioners will carry a label showing the unit's cooling output in kilowatts (kW). Every room and every home is different, so we recommend that you get a licensed contractor to visit your home and provide a detailed heat load calculation. Using the calculator below, however, will give you a rough idea of the cooling output you will need: 1. Please select your nearest regional 2. What is the ceiling area of the room you wish to Uninsuladed metal roof overInsulated metal roof overUninsulated tiled roof overInsulated tiled roof overUnairconditioned room over with carpeted floorsUnairconditioned room over with no carpets 3. What is the floor area of the room you wish to Uninsulated suspended timber floor enclosed underInsulated suspended timber floor enclosed underUninsulated suspended timber floor unenclosed underInsulated suspended timber floor unenclosed underUninsulated suspended concrete slab enclosed underInsulated suspended concrete slab enclosed underUnairconitioned room below