The Minimum Efficiency Reporting Value, also known simply as MERV, measures the performance of air purifiers, specifically large purifiers intended to clean an entire house or building. Large, whole-house purifiers are not evaluated in the same manner used to measure the effectiveness of small, portable air cleaners, which are sometimes given Clean Air Delivery Ratings (CADR) instead. Whole house and building air purifiers usually receive MERV ratings of between 1 and 16, though the upper limit is sometimes extended to 20. Common residential air purification systems tend to fall within a narrower range. Higher numbers translate to more effective air filtration. According to the online encyclopedia Wikipedia, "The scale is designed to represent the worst case performance of a filter when dealing with particles in the range of 0.3 to 10 micrometers." Particle Size Removal Efficiency Particle Size and Typical Contaminant Typical Air Filter Type < 0.3 μm Virus (un attached) Carbon Dust Sea Salt All combustion smoke - - - - 0.3-1 μm Bag Filters Box filters - 1-3 μm Pleated filters Box Filters - - 9 - 8 - - 3-10 μm Pleated filters Cartridge filters Throwaway 7 - - 6 - - 5 - - 4 - - > 10 μm

(Table Data Source - United States Environmental Protection Agency) The MERV rating system was initially created by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (or ASHRAE for short) in 1987. However, this evaluation system was based on older methods that date back to 1968, when ASHRAE issued "Standard 52," the first formal testing standard for filters. crc air sensor cleaner halfordsAccording to an article by engineer Donald Newell, the purpose of the Standard has not changed since its early days, and is designed to determine the following attributes of air filters:air duct cleaning duluth ga MERV ratings measure only the first quality, however. air duct cleaning sunnyvaleThe MERV rating of an air cleaner is determined according to updated standards set by the ANSI/ASHRAE Standard 52.2-1999.

Air cleaners are given MERV ratings based on the results of a series of tests. Simply put, the process works as follows: After this is done, the process is repeated five more times, so that there are ultimately six measurements for each of the twelve categories. The MERV number is assigned based on the worst result. Hence the "minimum" in "Minimum Efficiency Reporting Value."Of particular interest is the column detailing what types of pollutants are filtered out at each level. Precise technical details will be less important to the average customer than an answer to the question, "What MERV ratings are acceptable for my home?" The United States Environmental Protection Agency provides some information on this matter. "Medium efficiency filters with a MERV of 5 to 13," it states, "are reasonably efficient at removing small to large airborne particles. Filters with a MERV between 7 and 13 are likely to be nearly as effective as true HEPA filters at controlling most airborne indoor particles."

Furthermore, the EPA adds that "medium efficiency air filters are generally less expensive than HEPA filters, and allow quieter HVAC fan operation and higher airflow rates than HEPA filters since they have less airflow resistance." HEPA (High Efficiency Particulate Air) filters are the top-of-the-line air filters. Most homes are not capable of having whole-house HEPA filtration systems installed without extensive modification. Therefore, the EPA's recommendation of filters with a MERV rating from 7 to 13 is something that potential customers should keep in mind. The National Air Filtration Association gives a roughly similar answer. The highest range it recommends for residential systems is 9-12; higher numbers are said to be suited for hospitals or commercial buildings rather than homes. An air cleaner's MERV rating is based on its ability to filter out undesirable particles from the air. Not all indoor air pollution is particle-based, however. Gasses contribute significantly to pollution as well.

The ability of an air purifier to remove particles is not predicative of its ability to remove gasses, so the MERV rating is not helpful in this regard. Newell's article cautions that air filters given the ASHRAE test "are likely to perform worse than predicted because of various installation conditions." This is known as the "installation effect." Therefore, it is important to remember that MERV ratings are assigned based on a purifier's performance in carefully controlled testing conditions, and not the "real world." And finally, as stated above, MERV ratings are only relevant to large air cleaners intended to affect whole buildings. Common small portable air cleaners do not have MERV ratings. The MERV rating system is a helpful way to describe the capabilities of different large air cleaners. It is determined through rigorous testing and is gives the worst-case performance of the filter, so the MERV number is not inflated. No one should forget to consider MERV ratings when shopping for such cleaners.

There are, however, other factors to consider as well, so it would be a mistake to think that buying the right air filtration system is a simple matter of picking the unit with the highest MERV.Schaal Heating and Cooling, Your Source for Professional Air Conditioning & Heating Services in Des Moines, IA The number to call for exceptional air conditioning and heating services in Des Moines, IA is ours. Not only do the professional HVAC technicians at Schaal Heating and Cooling excel in the installation and replacement of heating and air conditioning systems, but they also offer exceptional repair and maintenance services in order to keep those systems functioning as well as possible. Dial our number, and we’ll help you to live in year round comfort. Of course, working with HVAC systems is only a part of what we do. We also offer comprehensive water heater and indoor air quality services as well. Whether you need a brand new geothermal system installed, or you just want to have your water heater annually serviced, we are the professional technicians that you can count on to have the job done right.

Schaal Heating and Cooling provides air conditioning and heating services near Des Moines, IA and the surrounding areas Modern air conditioning systems are now capable of cooling homes with greater reliability and efficiency than ever before. This will only be the case, though, if you schedule your air conditioning installation, replacement, repair and maintenance services with qualified professionals. If you are reading this, you are well on your way toward doing so. Contact us today to discuss your air conditioning options with a knowledgeable professional. We have the information that you need to choose your AC with confidence. Geothermal heating and cooling systems are growing more and more popular these days. Their draw is pretty easy to understand, once you understand how it is that geothermal works. Geothermal systems utilize heat pump technology to offer users both heating and cooling capability with just one system. The heat is drawn from the ground in the winter, meaning that you won’t have to worry about low air temperatures negatively impacting your geothermal system’s heating output.

Let us set you up with a great geothermal heating and cooling system. Even if you love the cold winter season, you must be able to heat your home successfully and efficiently. That is only going to be the case if you schedule your heating services with professionals that you can count on to get the job done right. No matter what type of heater you may choose to use in your home, you can trust our qualified heating technicians to install and service that heating system with the utmost skill and care. Call now to get the heater that you need in your home. Our access to immediate, consistent hot water throughout our homes is truly one of the greatest luxuries that we enjoy as modern homeowners. Make sure that your water heater is of the right size and design for your home and personal user preferences, and that it is in great shape for working properly. We are more than happy to install and service your new water heater for you, as well as to replace an old, inefficient or unreliable model.