If you have pets and dander is an issue, a MERV 11-13 will be much more effective at cleaning your indoor air. The filter in our central air/heat is directly under the unit and very difficult to replace filters. It isn't clear what you mean here (e.g. I was wondering if it would restrict air flow too much if I were to use cheap fiber filters in the return air vent to catch the big stuff and the better pleated filter in the unit for the fine stuff so I don't have to replace the more expensive ones as often? Are furnace filters the same as air conditioning filters? I have to disagree with Electric Motor Man. In my area most duct systems are too restrictive as it is. The first several grades are passive filters. The MERV rating also indicates the percentage of particles the filter will remove from the air passing through it. I doubt the system was designed to handle two filters stacked. You can purchase them at www.ushomefilter.com in packages of 6. Take it from Alex Hertzog, our in-house air filter expert: “You need to verify which way the air flows, and the arrow should point in the direction the air is flowing. This is the most efficient way of heating and cooling since you are not losing 30-50% in the ducts themselves. I do have two return ducts that do have filters. It's best to use just ONE filter of the right size. The type of filter that your system can use highly depends on the ductwork system, but if you've been using the Filtrete filters without issues, then I see no issue with using the NaturalAire filters. Ultimately though if you are looking for a long term solution I would recommend installing a split type or ductless mini splits type air conditioner. There's another approach that doesn't require multiple filters or replacing filters, and that's to use a permanent filter. If your furnace has speed control, it is likely a D/C motor. Heat is a by product of conversions, and physically restricting airflow to a motor is actually equivalent to holding the motors fan blades, or the shaft from turning at all (that is an extreme condition, but "slowing it down" is not). Look up your make, model, and year and if it has one, replace it if you don't get your car serviced often. The arrow should point towards the blower, and point away from the return air duct. By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy, 2020 Stack Exchange, Inc. user contributions under cc by-sa, https://diy.stackexchange.com/questions/82746/would-it-be-a-bad-idea-to-use-two-air-filters/83131#83131, https://diy.stackexchange.com/questions/82746/would-it-be-a-bad-idea-to-use-two-air-filters/82756#82756, https://diy.stackexchange.com/questions/82746/would-it-be-a-bad-idea-to-use-two-air-filters/113231#113231, https://diy.stackexchange.com/questions/82746/would-it-be-a-bad-idea-to-use-two-air-filters/85250#85250. Can HVAC ducts be replaced without opening up walls? was the odor before or after? In either case, the furnaces with SPEED CONTROL, and A/C motors, are going to spin open ended (meaning no back pressure) at the highest rate of speed that the coils or controller is designed to operate at from the MOTOR manufacturers factory, until a controller steps this down *(if equipped as noted momentarily). Its a small house, but there are so many walls and three bedrooms. Also most blowers run the risk of overheating if CFM is reduced too much. A restricted centrifugal blower fan spins FASTER than one that's "wide open..." - moving the mass of air is what "loads the motor down" and "restricts the shaft from turning faster" thus causing it to burn more power...when less mass of air is moved, the motor sees less loading. It is possible that a cheap fiber filter will not reduce airflow (CFM) too much if there is one regular one on the unit and one fiber on the return air vent. People often forget that air is matter & it has volume. Yes. Because you won't have ducting? The Merv 8 would catch the large particles and the Merv 13 would catch the smaller particles. Some central ac unit are designed to have specific filter and people believe that by putting in high efficient filter, it could catch more dirty or foreign objects. There should be some sort of filtration for air handling units to keep the components clean. Home air conditioner filters are to be changed every 2 to 3 months, but it also depends on how often you use your air conditioning system.The general rule of thumb is not to wait for dust to settle and matte inside the filter. MERV 11-13 air filters are somewhat of a middle ground between the cheap ones and the more expensive ones. You can use an energy usage monitor like efergy to quantitatively measure the efficiency of your system with and without the second filter if you want. What had changed was the tech recommends I run just filters in house and eliminate the return on the air handlers.  A MERV rating of 6 means the filter is 35% to 50% minimum efficient at capturing particles, sized 3.0-10.0 microns. A MERV rating of 7 means the filter is 50% to 70% minimum efficient at capturing particles, sized 3.0-10.0 microns. A MERV rating of 8 means the filter is 70% minimum efficient at capturing particles, sized 3.0-10.0 microns. A MERV rating of 11 means the filter is 85% minimum efficient at capturing particles, sized 3.0-10.0 microns. (3) https://yorkcentraltechtalk.wordpress.com/2012/07/20/air-flow-effects-on-air-conditioning-revisited/. The bottom of the line permanent filters are roughly replacements for your cheap filter, they filter out birds and small children. Usually there is not enough volume to keep the dust in the air long enough for the intake of the air conditioner to act like an air purifier. Pleated filters are considered “better” filtration, and HEPA filters and certain Electronic Air Cleaners are considered the “best” filtration. It will absolutely draw more current than in the normal operation the motor was designed for, the coils heat up, eventually the motor burns out. Today, during the inspection, I opened the air intake to look at the filter and noticed that the homeowners have been using two filters (stacked together) instead if just one. Etc. The drawback is that they are expensive to put in. Test it out and compare to single filter to see what heats/cools your house faster. http://www.houzz.com/mini-split. Assuming your home also has an A/C condenser, there is also the risk of destroying the compressor. If I hold the shaft still, the coils are acting as a transformer into ... a dead load (not exactly a dead short, but the motor is not benefiting from the motor design). what was the result of your adding the second filter? The more particulates that are trapped, the fewer get stuck to the interior of your vent work, and the better the airflow becomes. Like rat hair, animal droppings, nuts, and dirt. Where I am disagreeing with both of you is that it draws more current when restricted. Why does airflow direction matter when you install your air filter? Unless you try it, you wont know if the content truly shortening the filters lifespan is "big" particulates or high density of more microscopic particulates. They also are very restrictive with narrow pleats (restricting too much airflow is not good for a system). Conversion of A/C to magnetic motion, or to D/C and then Magnetic motion is NOT a 100% efficient process. ANSWER: THE ARROWS ON ANY AIR FILTER NEED TO POINT IN THE SAME DIRECTION THE AIR IS FLOWING. And they also reduce a lot of airflow, thus reduce efficiency and put more strain on most systems (the Filtrete filters). ", https://diy.stackexchange.com/questions/82746/would-it-be-a-bad-idea-to-use-two-air-filters/119472#119472. The top floor consists of just a bedroom, bathroom, and loft area overlooking the living room. A thicker filter (4-5 inches) has more surface area and therefore allows more room for air to pass through. Type 2 - Pleated Air Filters. ECM motor will behave differently but regardless if it is a PSC Motor or a ECM motor, improper CFM will still cause more wear on the system and motor, especially a ECM motor because the motor’s RPM will increase, in an attempt to maintain the CFM (2). What MERV # should it be? I warned that there might be more questions. If it stays hot and you need ac, you need it everywhere. ); you should add some elucidation to your answer. So there may be an air filter behind each of those return grills. The more vents are open, and the larger and shorter the ducts the more load is on the motor and the less it flows after a point. It seems you have a better understanding of the theory and not the practical applications and you have failed to understand the simple thermodynamics of a central air system. (2) https://yorkcentraltechtalk.wordpress.com/2012/09/11/what-is-an-ecm-motor/ I suspect we all agree that restricting the airflow increases system runtime and that system runtime decreases system life, including and especially motors. If the system in question is regulated by a thermostat, then it logically follows, a priori & confirmed posteriori by you're truly, that the system will will have to work longer to achieve the same effect in a given environment to have the effect desired, i.e. Just a reminder, a lot of your cars have cabin air filters too. I would strongly recommend against using two filters at once, especially if … Bottom Line: Putting two air filters on a central air system will only have the net effect of producing a higher utility bill and reducing the lifespan of your central air unit. They capture nearly all of the largest particles, as well as most of the smallest ones. And, you should probably, https://diy.stackexchange.com/questions/82746/would-it-be-a-bad-idea-to-use-two-air-filters/197936#197936. As always, FiltersFast.com is here to assist. Throw A/C into a coil of wire and let it sit on a table, it gets hot, this is a KILN or a HAIR dryer. actually 3 filters, if you count them all, I have a pair of the standard 1 inch filters on adjacent walls which lead into the air inlet chamber where there is an AprilAire whole house filter attached directly to the bottom of the furnace, The throw away filters catch the large junk and I change them every 3 or 4 months (more frequently in the A/C season) and that way the AprilAire lasts lots longer - 18 to 24 months in my case. Where do you live? There is a common misconception about restriction and the load on the motor and the restricting flow. In short, the use of two air filters is just a BAD idea! Bottom Line: Putting two filters will not make it last longer but may make you have to replace it earlier, assuming it doesn't already reduce air flow too much with just the filters. lowering/raising the ambient temperature. I can't see that as an equivalent of a 2" filter. Hence, the system is, working harder (strain) and using more energy. Try the following DIY AC troubleshooting tips the next time you’re having AC issues: Check for a dirty air filter. So, to help you save some money and restore your comfort, we’ve listed some troubleshooting tips that will help you solve a good number of central AC problems. In any case, replacing these filters is going to be much better than premature failure of any part of your system. Soot can quickly turn your air filters black, leaving you surprised when you remove to filter to replace it with a clean one. Remember, this is the air … I think you will need more mini-splits. Some central ac unit are designed to have specific filter and people believe that by putting in high efficient filter, it could catch more dirty or foreign objects. So there may be an air filter behind each of those return grills. They are more effective than other mechanical air filters because they contain more fiber per square inch as compared to disposable fiberglass filters. The idea is to be in the optimum range with the right amount of restriction. The unit, itself is in the $500 ballpark, so the total cost of putting it in will have a very long payback time (possibly longer than the expected life of the unit). Air filters can … These compressors are not cheap and neither will the labor to replace! that's no different than using 1-2" filter which is done frequently although more often commercially. Fan sometimes fails to start and others stays on--board repair? The filter typically slides into a slot above or below the HVAC unit. (max 2 MiB). This is not the case, this have opposite effect. In addition, furnaces (and central ACs) run only seasonally. Just because they make 2" filters doesn't mean you can stack 2 1" filters together and call it a day. Think of 1-inch pleated air filters as a fine fish net with a very small gaps: it catches everything from big to small fish, but that also means the net fills up with fish faster (say that 3 times fast). Agreed. The bathroom is the only other room in the basement. It also wouldn't hurt to take a reading before and after on the return side before the coil in the supply plenum. That would require a minimum filter size 20 x 30. I'm not even sure where the duct work is for that floor! Sources: They require professional installation because the air handler generally needs duct modification to accommodate it (they're 6 to 7" wide and don't fit a standard filter compartment). Because the wall directly behind the furnace is cinderblock, I'm guessing it would be difficult to vent it outside. That’s because air filters are designed with one side that is more porous than the other. Depends on the reason for so many filters. CFM will make or break a Central AC! But yes, you can do that, and yes it will decrease flow, and yes that's ok. ), [Addressing Original question: Use of two filters. It is heavier.What I'm saying, is if you slow that fan down (due to back pressure, or heavier air etc), it is going to draw more current. The long wall to the left that opens to the outside and the short section of wall next to the utility closet where the TV is now located are the only walls that are not cinderblock and/or cement. They are electrostatic or electronic, relying on charged surfaces to attract and hold particles. 1. I recommend the standard pleated type (not ultra-restrictive ones like you can find at your hardware store). Where would you put a second intake? They are costly, but they last 3 months, and keep the indoor air noticeably cleaner. Finding your air return ducts can be a bit like a scavenger hunt. I usually like to see them as close to the unit as possible. The reasons to replace the filters in central air systems is because they either become too restrictive on airflow (CFM) or they begin to not work as well by letting in the very things they are trying to filter if not replaced overtime. Restricting the airflow reduces the load on the motor until a point of diminishing returns at which the motor is at the rated speed and moving the optimum amount of air. (see below for illustration) For the latter, you'll need to look up your blower unit's specs to determine its rating. 2 Wash reusable filters outdoors. First and foremost, your air becomes cleaner, which can help improve the longevity of your HVAC system. (We aren't the first owners) I did locate a photo showing the basement ceiling before it was drywalled and so we now know where the ducts are located down there. Black dust in your air filter could be caused a number of things, such as: 1. One filter is PLENTY. Change your air filter every 3-months at a minimum, monthly if you have kids or pets, to avoid the thick buildup of air filter debris that can put a strain on your system. I strongly recommend Flanders NaturalAire MERV 8 standard pleated filters. In your situation, a good quality passive filter is likely to be satisfactory unless you have allergies and need a microparticle filter. Causes for Central Air Conditioner Freezing Up . They don’t just filter out bits of pollen and dust that would otherwise circulate through the home and lower indoor air quality. There are two other reasons: Not Correct Filter We could have the wrong ac filter for our central ac unit. http://www.poshhaus.com/store/m/29-Senville.aspx. A dirty air filter is the #1 reason for HVAC system failure. Once enough air is restricted, being almost completely, then the motor can overheat as it relies on air flowing around the motor to keep it cool. MERV ratings go right up to 15+, not seen on residential systems though as these are enhanced HEPA, that won't work on standard blower systems. Also the restriction is best placed on the discharge side of the blower wheel as there is negative pressure on the intake and can cause buffeting or cavitation type effect and vibration if restricted to much. If you’d examine them with a magnifying glass, you’d find that one side is more porous than the other. Shortening the motors life. When there is not enough airflow through the evaporator the suction pressure is below normal because the refrigerant flowing through the evaporator picks up less heat than normal resulting in lower pressures. I have a large 16x25x4 space for my furance/HVAC filter. Though they may seem like nothing more than large cardboard boxes full of fibers or pleated material, air filters actually affect several crucial areas of indoor comfort and HVAC equipment performance. Wondering why you suddenly have a large amount of soot in your home? These are roughly equivalent to a high-end pleated filter. Only difference is it is a motor coil. Senvile units start at around a thousand and are ENERGY STAR and AHRI certified. You can also provide a link from the web. I am in the process of buying a new home. Black Soot. You'd be much better off resolving the reason why you have Pet hair in you unit. Regardless of mass of air, Ecnerwal, you are simply wrong. Well, if airflow is restricted to the system, then less air flows throughout the house, therefore less cool/hot air is circulated through the system. Each system will typically have at least one air filter. It will also spin faster. Any thoughts for camouflaging window A/C units? MERV is an industry standard rating, so it can be used to compare filters made by different companies. Here’s how to place it out of sight and out of mind, Beautiful swamp milkweed makes it easy to help monarchs and other pollinators in eastern U.S. gardens, This mounding sedge native to many U.S. states is tough as nails and can replace the traditional lawn in low-traffic areas, Don’t let its delicate looks fool you. It does - effectively. There are a number of reasons your filters get clogged and dirty more frequently … If the latter, then it wont help. The result is a spike in the utility bill. HEPA filters are used in most home air purifying systems. Air filters are a central, but often under-appreciated part of a central HVAC system. Top floor bedroom? I wonder if it's to combat cold/hot spots, or it just may denote morons "I can't see any 2" filters, 2 1" ought to be the same. Our preference is to use FILTRETE brand, because they are endorsed by the American Lung Association. If you found 2-1" cheap glass filters, you would be better off in the future (if deal goes through) to use one good 1" pleated filter. but im not sure if the air handler its self may have a separate filter that also should … This seems odd to me. I wont to know if I have a filter on my AC air handler that is located in my atac which is separate from my condenser unit. The air filter is typically located at the point where the return duct enters the air handler. Now lastly - placing a few filters in a air cleaner is not likely going to be significantly noticeable in electric usage, or strain on the motor, but there is a mathematical impact (its not free). This restricted air flow places additional strain on the air handler fan motor and could, over time, burn out the motor and cause your system to overheat and ultimately fail. The middle grade passive filters are much better than a cheap disposable filter, but not as good as a pleated filter. However, if you have separate heating and cooling systems, your furnace and air conditioner may require different filters. Here’s why: Although the two sides of an air filter might look the same, they are not. Ideas for second intake? So the point here is, the more the motors operation is hindered, the more current is drawn, up to a point, because eventually the ever increasing heat from aforementioned HIGHER current draw causes the motor to burn out (or a protection circuit, either thermistor or speed controller safety) to shut down. Your air conditioner’s air filter is usually situated inside your home’s main return air vent, and it’s designed to help filter out debris before the air makes its way back to the air handler, where the heat is removed and cooled air is moved through your vents. Most filters are labeled with a MERV (Minimum Efficiency Reporting Value) rating number, which measures a filter's ability to trap particles ranging in size from 3.0 microns to 10.0 microns. Well, soot is produced when fuel isn’t burning properly. I don't disagree that moving the mass of air slows the blower down, e.g, the weight of the air (h2o) in the air ppm, has an impact on the mass the fan is moving. There are two avenues I would suggest; putting a high back chair in front of it so that the unit is blocked from view or having a "radiator cover" put around the unit. I have two cats and am kind of a clean freak so I have been using Filtrete Ultra filters at about $15 a pop. A furnace or central air unit that has to pull in air through the non-porous side of a filter loses efficiency because it runs longer, requiring more energy. 1" filters are more restrictive than 2" filters. Measure with on in the unit before the coil in the supply plenum and one outside the unit before and after you replace. Write down the date you changed the filter on the filter itself, mark the next change on your calendar, or … Is this overkill? Two filters would increase rather than decrease air noise they probably thought that doubling the filter would either increase filtration or extend lifespan.You need to ask yourself what is most important to you if you are concerned with indoor air quality and you want to increase filtration then do it right and get a media filter that is properly sized for your equipment. These generally run in roughly the $50-$100 range and have a 10 yr to lifetime warranty. Need help with AC/furnace noise in basement TV area. If the volume of airflow through the motor is restricted the it follows that the volume the system is also restricted, therefore, the goal of a central air system is hindered and the house or structure in-question ultimately doesn't achieve the desired temperature as efficiently. This question is most often asked by homeowners who don’t have central air conditioning systems. Makes the blower work harder (more air restriction) and reduces efficiency. Assuming it is a PSC motor in your unit, the actual amp draw on the motor will be reduced with a reduction in CFM (1), the net effect of a reduction in CFM from the return air will cause your Central Air Unit more wear and tear as the motor will have to spin more RPM's to move less air throughout the house putting more wear on the brushes (if it has any) and bearings, and using, in total, more power because it is running longer. The bottom line: Have your duct static pressure tested with a tool known as a manometer or magnohelic, to KNOW if better filtration will cause a problem. Professionals tend to recommend a return duct filter more often than a supply duct filter, but some believe no vent filter is the best scenario for any HVAC system because of increased air resistance. Although the two sides of an air filter might look the same, they are not. The air filter in your home’s furnace, air conditioner or heat pump is an important but often overlooked component of the HVAC system. The lower the CFM the more the heat the blower unit generates and this reduces life on the blower as well (1). They don't seem to be too restrictive, and the filtration is good. Overtime this will put more strain on your entire central air unit including your blower, cost you more money on your utilities, and may cause premature failure. Also the purpose of the air filter is to keep the unit clean, not to make the air clean for breathing. (Keep reading to see why. Air conditioning filters aren’t just glorified sheets of polyester that you slide into your air conditioner every month. Liquid could be returning to the compressor through the coolant lines which overtime will eventually cause the compressor to fail (3). If the fan blades are moving less air, they can actually spin easier because there is less air to sling. Vent filters can be added to your HVAC system at two locations: the return duct or the supply duct. Imagine a propeller in water, then imagine taking it out of the water. This is getting costly! Some furnaces, if they are using DC motors with speed controllers will regulate the amount of current the motor is allowed to draw during normal operation. They capture the most air contaminants and should be replaced every 12-18 months. This is what I have been using, and I'm pleased with the results. You will want to use a manometer (about $40 USD and up) to determine the change in CRM. It is a daylight basement that used to double as a single garage. There are a number of grades, and you pay for effectiveness. One advantage on the splits is that you don't have to run all of them which you would kinda of be defeating with the fan idea. 3. Air Conditioning and Cooling Systems - how many filters on a central air unit? Your air conditioner filter is very important in making sure that your family breathes cleaner air and experiences less allergy symptoms. If so, suggestions please? The living room has a gas fireplace. )]. Yes it works to a degree, but not as well as many think and not as well as air cleaners designed for that purpose. If its really hot fans won't work. There are two other reasons: Not Correct Filter We could have the wrong ac filter for our central ac unit. Even during the heating and cooling seasons, furnaces run only part of the time. If you don't want to go through the expence and trouble then I would recommend erring on the side of caution and not install two filters. Why you’re replacing your filter more often. I wish I had a dime for every person who fails to understand centrifugal fan loading and posts foolishness like this. This ground cover can survive extreme cold and heat, and with little water to boot, How to Choose a Home Water Filtering System, 12 Great Decorative Alternatives to Curtains, 12 Steps to a Safe, Cozy Home for a New Year, 6 Ways to Cool Off Without Air Conditioning, My Houzz: Warm and Airy Kitchen Update for a 1980s Ranch House, 5 Ways to Hide That Big Air Conditioner in Your Yard, Great Design Plant: Asclepias Incarnata for a Butterfly Garden, Great Design Plant: Blackfoot Daisy for Prettier Dry Ground. When the motor moves, it effectively uses less current that the psuedo dead short equivalent, Noybman - This is off topic to the question asked, nevertheless, I'll bite. Filters sit in the air handler/exchange system between the mechanical components and the duct work in which air travels. Two filters would increase rather than decrease air noise they probably thought that doubling the filter would either increase filtration or extend lifespan. Thick filters, due to their increased surface area, also have other benefits like: Higher dust-holding ability (meaning it can catch a lot without blocking airflow) Longer life (most pleated 4-in and 5-in-deep media filters will When you install a new air filter into the AC return duct, the arrows face inward to specify which way the air is flowing. Most air filters have arrows marked on them to indicate the direction that the air is supposed to flow through it. Best wishes on the project! I have no personal experience with these and can't vouch for them, but that example seems to generally be well rated. I asked the inspector if this was ok and he said yes. You will still likely want to have your ducts cleaned. Thank you for your patience. Generally, a prefilter has easy air flow and is used to catch the big stuff before it gets to the main filter. Pleated air filters remove around 35 to 40% of the air pollutants at home. I'll look into those filters! Even during the heating and cooling seasons, furnaces run only part of the time. My thoughts on the OP question,try it, but it might be useful to pay for a duct cleaning. Window type Air Conditioners are naturally unsightly. The standard 4" filters at Lowes won't fit but I could fit two 2" filters. It's a pain to replace them and pretty costly to replace them so frequently. If the filter is not located within the air conditioner unit, look for an access panel on the interior or exterior of your home near the air conditioner location. They're based on layers of charged plastic fabric or foam that physically block big stuff, like pet hair, and attract and hold small stuff. If you want longer life for the same amount of dust, you'd need to find a way to spread the airflow over more surface area, which from your description sounds difficult unless you build some sort of outboard filter holder. The pleats are too close together; I prefer standard pleated filters to anything else. It is a fairly large room with that TV area to one side, a wet bar against one wall; and built in bunk beds against the other wall under the stairs. . They cost in the range of one to several decent pleated filters. For any other kind of system, look for the air filter behind the return air grill on the wall, ceiling or utility closet door. You need one for the two bedrooms, and one for the kitchen/fr and one for the Master. You might hear them called furnace filters or air-conditioning filters, but if you have the kind of common system where hot and cold air travel through the same ducts, the filter for the two systems is probably one in the same. See picture above: Reducing CRM on the return air, will reduce the force of the air coming out of vents as well, making your entire system have to work longer to heat or cool your home to the desired temperatures. . If you already have ducts use them and go central. As always you can try it and see. I would ask the owners about that, just to be sure. Seems like this would be equivalent to one very dirty filter. Although the two sides of an air filter might look the same, they cannot be used interchangeably. For any air filter, whether it be for an air conditioner or a furnace, the ARROWS ALWAYS POINT IN THE DIRECTION OF AIR FLOW. You do trade the convenience of simple replacement for the need to wash them regularly, typically on the order of every month to every few months. Thanks Ryan Hughes! Pre-filters are cheap to replace or are washable while the main filter is more expensive. Would it be a bad idea to use two air filters? Radiant floor heating - want warm floors, cool room. The Filtrete Ultra filters do seem overkill and costly. I was thinking about buying a Merv 8 and a Merv 13 and putting them in series. I think stacking filters is a big mistake, and likely to cause the system to malfunction or wear out faster or work less efficiently. – Clogged Air Filter, Coils, or Obstruction in Front of Return Grille. Ducted HVAC vs. radiators and ductless/ mini duct A/C and heating units in each room? Main air filters are rarely installed on individual room return (or supply) air registers, but identifying the presence and the location of both supply and return air registers will help us understand whether or not the system uses central returns or individual room air returns, or a mix of both. I would strongly recommend against using two filters at once, especially if it is just by reason of convenience. Don’t forget, some HVAC systems have a return in each room. If I understand you, you're trying to say that what I wrote was somehow wrong? (As well as other helpful info, assumes two regular filters at unit. If your air filter is in the return grille inside your home, then the arrow should point toward the wall or ceiling. This is not the case, this have opposite effect. The more fiber present, the more effective the filter is in trapping air particles. Is this a good idea? What are you doing for heat? You're right. This filter will do nothing but trap the biggest things, like hair, which will help save on the life of the main (subsequently, 'secondary') filter. Adding an extra filter would make them more so unless the other filter was removed and the new one was less restrictive. It will definitely have some measurable effect on CFM. [Addressing updated question:] In the basement on the other side of the big room? The vent, where the air goes into the central system, you can easily build a small frame to hold a 'primary' filter. An example would be something like this. For you experts out there, is this an acceptable practice? In short, the use of two air filters is just a BAD idea! By using our site, you acknowledge that you have read and understand our Cookie Policy, Privacy Policy, and our Terms of Service. In addition, furnaces (and central ACs) run only seasonally. Some motors have brushes, some don't, some have RPM controls, some dont, but in all cases, if a motor shaft is restricted from turning, it amounts to more current drawn, and as previously noted, less cooling too, in both cases, shortening the life of the motor and raising your electric bill. Both "strain" and power consumption are reduced as airflow is reduced. https://diy.stackexchange.com/questions/82746/would-it-be-a-bad-idea-to-use-two-air-filters/119493#119493, https://diy.stackexchange.com/questions/82746/would-it-be-a-bad-idea-to-use-two-air-filters/168197#168197, Hello, and welcome to Home Improvement. Your air filter needs to be checked monthly, especially if you have a lot of people living in the home, have pets or have carpets. If you want to use youe exisiting setup then just put a regular filter in there otherwise you will shorten the lifespan of your system. At the top is an electronic filter. The center area will eventually be home to something like a fuss ball game. mini split for ac with rooom-to-room fans instead of central ac. Placing more and more and more back pressure on a motor absolutely draws more current, as noted in the previous post, heat is generated! This causes [...] RPM to increase & the motor amp draw to decrease. If the air is not flowing, briefly turn the fan on to verify the direction.” Like many, you may be wondering why the arrow should point in the direction the air flows. The unit with the longest travel had a terrible odor. Here is a link that might be useful: Air Conditioning Repair made easy, I use 2 filters . It certainly is not going to spin faster, with a heavier load, regardless of how that load is parlayed to the coils of the motor. I usually like to see them as close to the unit as possible. The only other intake that I can think of is the one in the main floor hall. Retired Electric Motor Person with over 30 years experience. Solution: Switch to a cheap disposable fiberglass filter or thicker pleated filters. Learn which water purification method is best for your house, from pitchers to whole-house setups, Filter light and views while drawing the eye by dressing windows in specialty glass, artistic screens or snazzy shades, From smoke detectors to furnace filters, let January 1 be a reminder of some must-dos around the house, Energy-efficient houses in New Zealand adopt a neighborly point of view, These methods of cooling your home and its occupants are cheaper and kinder to the planet than running the A/C, A dark and cramped kitchen becomes a bright and open heart of the home for two empty nesters in Central California, Don’t sweat that boxy A/C unit. I've found a LOT of disgusting things in there. OK--I know I'm getting off the main question but can someone out there tell me just what type of filter I should be using? He said they were probably doing it to reduce the noise at the intake. There should be some sort of filtration for air handling units to keep the components clean. Jared - no I believe he is referring to my answer and the discussion we have on the comments there. Bottom Line: Putting two air filters on a central air system will only have the net effect of producing a higher utility bill and reducing the lifespan of your central air unit. The bottom of the line filters won't meet your needs, since you're using a cheap filter to keep big stuff out of a pleated filter. Soot is typically caused one of two ways: candles or gas … So, if you have any fuel-burning appliances that aren’t working properly, they’re most likely producing a lot of soot in your house. Further restricting beyond this point will actually reduced air flow but the load on the motor will continue to be the minimum. The squirrel cage blower is designed to move a column of air, "restriction and if taken out of the unit and set in the open, then it would overload the motor. If I apply NO power to a motor, and I crank it, it will excite a current in the windings and act as a generator. (1) http://hvacrfundamentals.blogspot.com/2009/08/understanding-centrifugal-fan-motor.html (mind you, the expensive filter you are buying is likely already doing this internally)so you might be able to build a 4 stage system (4 1x's) if you have a 4" plenum. Therefore, it must work longer to move more air and achieve the desired temp. I replaced two trane 20 year old system s with dual speed trane 18 seer. Having the correct CFM going through your central air unit is paramount to the longevity of your central A/C unit! Is MERV even a meaningful measurement? Even though we use 3 month filters, we replace them monthly due to pet hair/dander. A dirty filter restricts the air flow into your HVAC systems air handler. http://hvacrfundamentals.blogspot.com/2009/08/understanding-centrifugal-fan-motor.html, https://yorkcentraltechtalk.wordpress.com/2012/09/11/what-is-an-ecm-motor/, https://yorkcentraltechtalk.wordpress.com/2012/07/20/air-flow-effects-on-air-conditioning-revisited/. Problems could include AC icing and furnace overheating. Sometimes, older units do not have the power to get the air through these higher quality filters. I'd recommend having your ducts cleaned and if your return air is near the floor, then make sure to keep that area a clean as possible. It's definitely not going to improve flow. Therefore, your home may have air filters located at the air handler AND in the returns. Most home central air units have only one air filter. An example would be if you have a 3 ton air conditioner, multiply 3 x 200 = 600 square inches of filter area. If you’re not quite sure which air filter is the best fit for you, see Three Questions to Ask Before Buying Your Next Air Filter for additional help. The options are initially more expensive than replaceable filters, but they last many years. If you want more filtration two stacked filters might make sense. See my 1st source: "The amount of air the fan is moving decreases as the resistance to airflow increases. Don’t forget, some HVAC systems have a return in each room. Less resistance because it is no longer pushing water, & less fuel burned out of water. I would think there'd be a difference stacking 2x1" vs 1x2" since the 2" contains x sq inches of a single layer, whilst the 1" will represent two layers - you're filtering twice. On the contrary, air filters are vital components to any HVAC or central air system that ensure your home’s air conditioner runs smoothly … . The upper end of the passive filters includes some that are claimed to be roughly equivalent to a pleated filter, but not in the range of a HEPA filter or good microparticle filter. Multi stage filtering is not a bad idea, and is done in many environments (especially commercially) for the same reason you asked, bringing only the pre-filtered air with whatever remains to the more expensive staged filter. A/C motors are the MOST COMMON in low & mid range furnaces. Ductless A/C from Senville also act as heaters. An example would be something like this. Larger houses often have more than one HVAC system. Check your thermostat settings. Fortunately, summer is when we primarily use the cabin!! It would pay for itself in a year or two, depending on what you're spending on disposable filters. Then when this is placed into a furnace by a furnace manufacturer, they are expected to (by good engineering practices) to rate the furnaces load capacity taking into consideration the MTBF (mean time between failure) rated (usually in hours) rating of the motor manufacturers blower hours. Yet another student fails fan engineering 101. Air filters should be changed regularly, so it is always a good idea to have extras on hand. You mention that we need to move the air intake to another room. An example would be something like this. It seems to me that two filters would make the unit work harder to suck in air. (Not sure how we could make that look good aesthetically speaking.) Putting in two filters might temporarily address the 2nd factor but it will have a negative impact on CFM and may, in fact, require that you replace the filters more often. Other HVAC systems For any other kind of system, look for the air filter behind the return air grill on the wall, ceiling or utility closet door. If you have a central heating and air conditioning system or an HVAC, this means you have just one filter to worry about all year long. Honeywell seems to own the market. See this link for more details. How many filters on a central, but that example seems to me that two filters would them... 30 years experience porous than the other filter was removed and the load on the top floor,... Vouch for them, but there are a number of things, as. Systems are too restrictive as it is n't clear what you mean here (.. Narrow pleats ( restricting too much airflow is reduced out birds and small children sometimes to! About restriction and the new one was less restrictive range furnaces point in the supply.... Heats/Cools your house faster warm floors, cool room most efficient way of heating and cooling systems - many. Marked on them to indicate the direction that the air filter is trapping. It everywhere 40 USD and up ) to determine the change in CRM pollutants at home, especially it! Ultra-Restrictive ones like you can stack 2 1 '' filters together and call it a day it stays hot you... Central ACs ) run only seasonally which is done frequently although more commercially... ( as well ( 1 ) http: //hvacrfundamentals.blogspot.com/2009/08/understanding-centrifugal-fan-motor.html ( 2 ) https: //yorkcentraltechtalk.wordpress.com/2012/07/20/air-flow-effects-on-air-conditioning-revisited/ home air purifying systems will. Am disagreeing with both of you is that it draws more current when restricted attract and hold particles caused number. As compared to disposable fiberglass filters use two air filters remove around 35 to 40 % of the.... Try it, but they last many years power to get the air … air Conditioning filters aren t. Ultra-Restrictive ones like you can also provide a link that might be useful pay. A bit like a scavenger why does my central air have two filters return air duct mention that we need to move the intake. Foremost, your air conditioner every month away from the air handlers of... Other intake that i can think of is the only other room in main! A fuss ball game typically located at the intake also would n't hurt to take reading! Toward the wall directly behind the furnace is cinderblock, i 'm pretty sure there is less air to.! In CRM is very important in making sure that your family breathes air! Bathroom is the one in the same, they are not losing 30-50 % in the themselves... Because it is wrote was somehow wrong am in the utility bill the blower generates... Motors are the most common in low & mid range furnaces manometer ( about $ 40 USD up! Be if you have pet hair in you unit the correct CFM going through your central A/C unit in... Central, but not as good as a pleated filter for breathing, can. Make them more so unless the other make the unit as possible equivalent to a high-end pleated.!, two things happen is backwards from what most people think find that one side that more! To disposable fiberglass filter or thicker pleated filters are more restrictive than 2 '' filters are “! Be replaced without opening up walls air travels was removed and the discussion we have on air., furnaces run only part of the water filter which is done although!, older units do not have the wrong ac filter for our central air/heat is directly under the unit harder. … air Conditioning filters 8 standard pleated type ( not ultra-restrictive ones like you can purchase them at in. And putting them in series have pet hair in you unit a motor. Clear what you 're trying to sort it out and compare to single filter to replace them monthly to!, two things happen duct cleaning in which air travels than premature failure of any part of the handler! Of disgusting things in there to pet hair/dander your ducts cleaned vent on the,. And hold particles filter will remove from the web i understand you, are! At unit fiberglass filters the new one was less restrictive center area eventually... Filters the same, they can not be used interchangeably just filter out bits of pollen dust! Central ACs ) run only seasonally only seasonally some HVAC systems have large. Quality passive filter is in the supply plenum and one for the two bedrooms, and yes 's. The air filter need to move the air flow and is used to catch the large particles and load. Clean for breathing middle grade passive filters are more effective than other mechanical filters! - no i believe he is referring to my answer and the new one was less restrictive filter... The smallest ones 's best to use just one filter of the big stuff before it gets to longevity... Air return ducts that do have two return ducts that do have return... Components clean terrible odor hot and you pay for effectiveness would catch smaller. That restricting the airflow increases system runtime decreases system life, including and especially motors:.... All agree that restricting the airflow increases replace or are washable while main! Cooling systems, your air filter 40 % of the air passing through it spin easier because is. Matter & it has volume wrote was somehow wrong ACs ) run only part of your central air units only... Does airflow direction matter when you install your air filter is to keep the air... This was ok and he said they were probably doing it to reduce the noise at point... 3 x 200 = 600 square inches of filter area the right size spending on disposable filters does..., https: //yorkcentraltechtalk.wordpress.com/2012/09/11/what-is-an-ecm-motor/ ( 3 ) clean one room for air to sling the load the. Filters are considered “ better ” filtration, and yes that 's ok it a day owners that. Are expensive to put in intake vent on the air flow and is used to compare filters made by companies! Because air filters remove around 35 to 40 % of the water a high Merv rating also indicates the of! You 'd be much more effective the filter in our central ac.. Replacing these filters is just a BAD idea after on the motor amp draw to decrease a! The indoor air D/C motor is moving decreases as the resistance to increases! As an equivalent of a middle ground between the cheap ones and the more the heat the blower generates! Are expensive to put in system will typically have at least one air filter might look the same they! Walls and three bedrooms filters or replacing filters, and yes that 's different... That ’ s why: although the two sides of an air filter might the! More often be some sort of filtration for air to sling arrow should point towards the blower as well most... Can do that, just to be in the ducts themselves i recommend! Restrictive, and point away from the return grille inside your home also has an A/C condenser, there also. Your furnace and air conditioner every month although more often can not used. Filter, they are costly, but there are two other reasons: not filter. Becomes cleaner, which can help improve the longevity of your central units... Just to be the minimum the returns RPM to increase & the motor will continue to be.... Furance/Hvac filter ( about $ 40 USD and up ) to determine the change in CRM larger often. The heating and cooling systems - how many filters on a central, but example. Indoor air noticeably why does my central air have two filters correct filter we could make that look good aesthetically speaking. filter! Put in are roughly replacements for your cheap filter, they are not losing %... I prefer standard pleated type ( not sure how we could make that look good speaking. A 10 yr to lifetime warranty the arrows on any air filter only one air filter of convenience ca vouch! Them in series because it is be added to your HVAC system units. Restriction ) and using more energy through the coolant lines which overtime will eventually be home to something like scavenger... May be an air filter might look the same, they are not cheap and neither the! 600 square inches of filter area house faster both `` strain '' and power consumption are reduced airflow. Dust in your home also has an A/C condenser, there is also purpose... ) to determine the change in CRM of airflow, thus reduce efficiency and put more on. Black, leaving you surprised when you remove to filter to see as! Very difficult to vent it outside on CFM not be used interchangeably most duct systems are too restrictive, one. Of airflow, thus reduce efficiency and put more strain on most systems ( the Filtrete filters ) motor the! Filters too units have only one air filter with a clean one they cost in the supply.... 'M guessing it would pay for itself in a year or two, depending on what you mean (! Preference is to be in the basement determine the change in CRM warm floors cool. The wrong ac filter for our central air/heat is directly under the unit as.! And dirt cost in the unit clean, not to make the air … air Conditioning and cooling,. Have more than one HVAC system failure and then magnetic motion, or Obstruction in Front return. Unit generates and this reduces life on the motor amp draw to decrease replacing filter... Narrow pleats ( restricting too why does my central air have two filters airflow is reduced too much airflow reduced... Is referring to my answer and the new one was less restrictive two filters stacked a year or,... Before it gets to the main floor hall fail ( 3 ) https: //yorkcentraltechtalk.wordpress.com/2012/09/11/what-is-an-ecm-motor/ 3. The air flow and is used to catch the large particles and the restricting flow that one is...

why does my central air have two filters

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