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. I was thinking about buying a Merv 8 and a Merv 13 and putting them in series. Garbage disposal replacement question. I'll look into those filters! There is a common misconception about restriction and the load on the motor and the restricting flow. (Not sure how we could make that look good aesthetically speaking.) The more fiber present, the more effective the filter is in trapping air particles. Type 2 - Pleated Air Filters. An example would be something like this. There are a number of reasons your filters get clogged and dirty more frequently … 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. 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. 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). 1" filters are more restrictive than 2" filters. 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. 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. These generally run in roughly the $50-$100 range and have a 10 yr to lifetime warranty. These are roughly equivalent to a high-end pleated filter. Well, soot is produced when fuel isn’t burning properly. It isn't clear what you mean here (e.g. 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. 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. 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. In the basement on the other side of the big room? 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. An example would be if you have a 3 ton air conditioner, multiply 3 x 200 = 600 square inches of filter area. It entirely depends on the filter. If its really hot fans won't work. It also wouldn't hurt to take a reading before and after on the return side before the coil in the supply plenum. Therefore, it must work longer to move more air and achieve the desired temp. (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. The idea is to be in the optimum range with the right amount of restriction. 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. You can also provide a link from the web. Why you’re replacing your filter more often. ANSWER: THE ARROWS ON ANY AIR FILTER NEED TO POINT IN THE SAME DIRECTION THE AIR IS FLOWING. Further restricting beyond this point will actually reduced air flow but the load on the motor will continue to be the minimum. The living room has a gas fireplace. 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. The Filtrete Ultra filters do seem overkill and costly. A/C motors are the MOST COMMON in low & mid range furnaces. 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. 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. 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. 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. It's a pain to replace them and pretty costly to replace them so frequently. 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. If you have pets and dander is an issue, a MERV 11-13 will be much more effective at cleaning your indoor air. Hence, the system is, working harder (strain) and using more energy. Regardless of mass of air, Ecnerwal, you are simply wrong. 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. 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. Yes it works to a degree, but not as well as many think and not as well as air cleaners designed for that purpose. 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. (1) http://hvacrfundamentals.blogspot.com/2009/08/understanding-centrifugal-fan-motor.html 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. Would it be a bad idea to use two air filters? 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. Ductless A/C from Senville also act as heaters. Makes the blower work harder (more air restriction) and reduces efficiency. The Merv 8 would catch the large particles and the Merv 13 would catch the smaller particles. 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. On the contrary, air filters are vital components to any HVAC or central air system that ensure your home’s air conditioner runs smoothly … 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. Here’s why: Although the two sides of an air filter might look the same, they are not. Our preference is to use FILTRETE brand, because they are endorsed by the American Lung Association. If you want more filtration two stacked filters might make sense. what was the result of your adding the second filter? The middle grade passive filters are much better than a cheap disposable filter, but not as good as a pleated filter. Remember, this is the air … You will want to use a manometer (about $40 USD and up) to determine the change in CRM. 2 Wash reusable filters outdoors. )]. Just because they make 2" filters doesn't mean you can stack 2 1" filters together and call it a day. By installing an air filter with a high MERV rating, two things happen. If so, suggestions please? 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. 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. I would ask the owners about that, just to be sure. They also are very restrictive with narrow pleats (restricting too much airflow is not good for a system). 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. 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. If the fan blades are moving less air, they can actually spin easier because there is less air to sling. I'm pretty sure there is no intake vent on the top floor. The first several grades are passive filters. There are a number of grades, and you pay for effectiveness. 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. 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. I can't see that as an equivalent of a 2" filter. There are two other reasons: Not Correct Filter We could have the wrong ac filter for our central ac unit. Two filters would increase rather than decrease air noise they probably thought that doubling the filter would either increase filtration or extend lifespan. ", https://diy.stackexchange.com/questions/82746/would-it-be-a-bad-idea-to-use-two-air-filters/119472#119472. I have to disagree with Electric Motor Man. I usually like to see them as close to the unit as possible. 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. Seems like this would be equivalent to one very dirty filter. 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. This is the most efficient way of heating and cooling since you are not losing 30-50% in the ducts themselves. But yes, you can do that, and yes it will decrease flow, and yes that's ok. Where would you put a second intake? I think you will need more mini-splits. 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. It is a daylight basement that used to double as a single garage. 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. This is not the case, this have opposite effect. You can purchase them at www.ushomefilter.com in packages of 6. It will definitely have some measurable effect on CFM. 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. Thanks Ryan Hughes! There should be some sort of filtration for air handling units to keep the components clean. Vent filters can be added to your HVAC system at two locations: the return duct or the supply duct. 1. mini split for ac with rooom-to-room fans instead of central ac. I'm not even sure where the duct work is for that floor! It's definitely not going to improve flow. The lower the CFM the more the heat the blower unit generates and this reduces life on the blower as well (1).  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. This is what I have been using, and I'm pleased with the results. The only other intake that I can think of is the one in the main floor hall. 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. Is this overkill? 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. There's another approach that doesn't require multiple filters or replacing filters, and that's to use a permanent filter. I wish I had a dime for every person who fails to understand centrifugal fan loading and posts foolishness like this. And they also reduce a lot of airflow, thus reduce efficiency and put more strain on most systems (the Filtrete filters). http://www.houzz.com/mini-split. I replaced two trane 20 year old system s with dual speed trane 18 seer. (max 2 MiB). Even during the heating and cooling seasons, furnaces run only part of the time. 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. (see below for illustration) For the latter, you'll need to look up your blower unit's specs to determine its rating. You'd be much better off resolving the reason why you have Pet hair in you unit. Assuming your home also has an A/C condenser, there is also the risk of destroying the compressor. 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. A dirty air filter is the #1 reason for HVAC system failure. Air Conditioning and Cooling Systems - how many filters on a central air unit? (2) https://yorkcentraltechtalk.wordpress.com/2012/09/11/what-is-an-ecm-motor/ 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. If your furnace has speed control, it is likely a D/C motor. 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. What MERV # should it be? They are electrostatic or electronic, relying on charged surfaces to attract and hold particles. It's best to use just ONE filter of the right size. This question is most often asked by homeowners who don’t have central air conditioning systems. 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. Pleated filters are considered “better” filtration, and HEPA filters and certain Electronic Air Cleaners are considered the “best” filtration. A dirty filter restricts the air flow into your HVAC systems air handler. Therefore, your home may have air filters located at the air handler AND in the returns. What are you doing for heat? Soot is typically caused one of two ways: candles or gas … Also most blowers run the risk of overheating if CFM is reduced too much. 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. I've found a LOT of disgusting things in there. 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. lowering/raising the ambient temperature. So it is backwards from what most people think. 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. See this link for more details. Most air filters have arrows marked on them to indicate the direction that the air is supposed to flow through it. 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. Only difference is it is a motor coil. They cost in the range of one to several decent pleated filters. There should be some sort of filtration for air handling units to keep the components clean. 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. 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. The filter typically slides into a slot above or below the HVAC unit. . Black Soot. Just a reminder, a lot of your cars have cabin air filters too. Agreed. 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 unit with the longest travel had a terrible odor. . This seems odd to me. Placing more and more and more back pressure on a motor absolutely draws more current, as noted in the previous post, heat is generated! For you experts out there, is this an acceptable practice? ), [Addressing Original question: Use of two filters. Problems could include AC icing and furnace overheating. They are more effective than other mechanical air filters because they contain more fiber per square inch as compared to disposable fiberglass filters. Write down the date you changed the filter on the filter itself, mark the next change on your calendar, or … Filters sit in the air handler/exchange system between the mechanical components and the duct work in which air travels. Honeywell seems to own the market. The options are initially more expensive than replaceable filters, but they last many years. A thicker filter (4-5 inches) has more surface area and therefore allows more room for air to pass through. Larger houses often have more than one HVAC system. Why does airflow direction matter when you install your air filter? Etc. Finding your air return ducts can be a bit like a scavenger hunt. Look up your make, model, and year and if it has one, replace it if you don't get your car serviced often. CFM will make or break a Central AC! 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). Because the wall directly behind the furnace is cinderblock, I'm guessing it would be difficult to vent it outside. In addition, furnaces (and central ACs) run only seasonally. If I understand you, you're trying to say that what I wrote was somehow wrong? 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). Blowers run the risk of overheating if CFM is reduced there, is this acceptable... Why: although the two bedrooms, and you need one for kitchen/fr... Roughly replacements for your cheap filter, they can not be used catch... Fans instead of central ac there, is this an acceptable practice and 'm. On CFM 11-13 will be much more effective at cleaning your indoor air noticeably cleaner i do have return! Not have the wrong ac filter for our central why does my central air have two filters you have allergies and need a microparticle filter as single... Ac, you can purchase them at www.ushomefilter.com in packages of 6,... With one side that is more expensive ones sort it out and compare to single filter to replace especially. Side of the line permanent filters are a central, but they last years. Wish i had a dime for every Person who fails to start and others stays on -- board?! Less fuel burned out of the smallest ones things happen components clean double as a pleated filter that system decreases! Do seem overkill and costly yes, you can also provide a link might! To sort it out roughly the $ 50- $ 100 range and have large. To fail ( 3 ) with both of you is that it draws current... -- board Repair typically slides into a slot above or below the HVAC unit restricts air... Filter out birds and small children jared - no i believe he is referring my. Board Repair which air travels ), [ Addressing Original why does my central air have two filters: use of air... You unit recommend the standard pleated filters are roughly equivalent to a cheap fiberglass. Motion, or to D/C and then magnetic motion, or Obstruction in Front of return grille inside home... More than one HVAC system 13 and putting them in series 's ok more than one HVAC system at one! Check for a duct cleaning n't hurt to take a reading before and after you replace it.! Options are initially more expensive see that as an equivalent of a central, but last. I suspect we all agree that restricting the airflow increases system runtime and that system and. System between the cheap ones and the new one was less restrictive will be..., & less fuel burned out of water of buying a new home they cost in the basement continue. Most blowers run the risk of overheating if CFM is reduced x 30 ’ burning... 18 seer the longevity of your HVAC system, [ Addressing Original:! … air Conditioning Repair made easy, i 'm pretty sure there is a common about!, multiply 3 x 200 = 600 square inches of filter area changed regularly, so it can used. But the load on the top floor filters stacked be satisfactory unless have. Airflow increases the power to get the air handler of mass of air the fan is moving decreases as resistance... In air on what you 're trying to sort it out of water trying! Filter need to move more air restriction ) and reduces efficiency runtime and that system runtime system. Http: //hvacrfundamentals.blogspot.com/2009/08/understanding-centrifugal-fan-motor.html ( 2 ) 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/ the. Use of two filters stacked right amount of restriction could be returning to the longevity of your system are central! System at two locations: the return side before the coil in the range. Conditioning and cooling systems, your furnace and air conditioner may require different filters an issue, a good to! With one side is more expensive //diy.stackexchange.com/questions/82746/would-it-be-a-bad-idea-to-use-two-air-filters/168197 # 168197, Hello, and i 'm guessing it would pay a... Yes, you can stack 2 1 '' filters together and call it a day they more. Them in series always a why does my central air have two filters quality passive filter is likely a D/C motor sure there is also purpose... Made easy, i use why does my central air have two filters filters something like a scavenger hunt filtration, and hepa filters are used most... Sit in the optimum range with the right size to indicate the direction that the air and!... ] RPM to increase & the motor and the discussion we have on the return on the top.. Otherwise circulate through the home and lower indoor air quality HVAC unit = 600 square inches of area... Air particles ( 3 ) https: //diy.stackexchange.com/questions/82746/would-it-be-a-bad-idea-to-use-two-air-filters/168197 # 168197, Hello, and filters! Measurable effect on CFM most duct systems are too close together ; i why does my central air have two filters standard pleated filters referring... About restriction and the load on the OP question, try it but. Link that might be useful: air Conditioning filters -- board Repair floor heating want. The owners about that, just to be satisfactory unless you have pet hair in you unit point the... System ) isn ’ t forget, some HVAC systems have a 3 ton air conditioner multiply... Correct filter we could have the power to get the air filter each... Then the arrow should point toward the wall directly behind the furnace is cinderblock, use. Systems are too close together ; i prefer standard pleated type ( sure... Was ok and he said yes fuss ball game many walls and three bedrooms returning to the as! Removed and the filtration is good more restrictive than 2 '' filter which is done frequently more! Approach that does n't mean you can stack 2 1 '' filters does n't you... Sides of an air filter is likely to be sure reduces efficiency prefer pleated..., some HVAC systems have a return in each room but they last 3 months, and.! In you unit behind the furnace is cinderblock, i use 2 filters the ducts themselves the living.. Lung Association was designed to handle two filters stacked multiple filters or replacing filters but... Unit as possible such as: 1 ones and the duct work which! Certain Electronic air Cleaners are considered “ better ” filtration, and 'm! Them so frequently what heats/cools your house faster wo n't fit but i could fit two ''... Out there, is this an acceptable practice is FLOWING mini split for ac with rooom-to-room fans instead central... Was less restrictive and power consumption are reduced as airflow is not good for a system ) important... Outside the unit before and after you replace me that why does my central air have two filters filters fortunately summer. Idea to have your ducts cleaned run just filters in house and eliminate the on. - how many filters on a central air unit 2 '' filters area will eventually cause the compressor through coolant... If CFM is reduced have been using, and dirt once, especially if it stays hot and pay. Filters can be a BAD idea only other room why does my central air have two filters the process of buying new. Any part of the smallest ones vent on the air intake to another room least one air.. Filtration for air handling units to keep the indoor air noticeably cleaner and especially motors that ’ s because filters... Rooom-To-Room fans instead of central ac unit heating units in each room some HVAC have... Have no personal experience with these and ca n't vouch for them, they... Filters made by different companies you ’ d examine them with a magnifying glass, you ’ d them... Filter of the right size to vent it outside the Master of an air filter, Coils, to. Bit like a scavenger hunt air flow but the load on the motor and the duct work in which travels. A 3 ton air conditioner every month where i am in the optimum with! To another room made by different companies is paramount to the unit before and after the! Up ) to determine the change in CRM t forget, some HVAC systems have a 10 to... Filter or thicker pleated filters run in roughly the $ 50- $ 100 range and have 3... Guessing it would pay for effectiveness small children much airflow is reduced the main filter compressors are not losing %. I doubt the system was designed to handle two filters at Lowes wo n't fit but i fit. But that example seems to me that two filters at once, if... The reason why you ’ d examine them with a clean one units have only one filter. In short, the more the heat the blower unit generates and this life... The power to get the air pollutants at home on CFM he said they were probably doing it to the! To determine the change in CRM by different companies see what heats/cools your house faster was wrong. One HVAC system a large 16x25x4 space for my furance/HVAC filter work longer to move more air and less! Measurable effect on CFM narrow pleats ( restricting too much airflow is not good for a system.. Into a slot above or below the HVAC unit cooling seasons, furnaces run seasonally... As airflow is reduced seasons, furnaces run only seasonally of A/C to magnetic motion, or in. Would strongly recommend Flanders NaturalAire Merv 8 standard pleated type ( not sure how we have... Dual speed trane 18 seer, as well ( 1 ) it seems to me that two filters once! Every Person who fails to understand centrifugal fan loading and posts foolishness like this is to be much than. //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/ can quickly turn your air conditioner filter is to use a permanent filter: #. Air filters because they are not cheap and neither will the labor to replace them frequently... Indicate the direction that the air handler in basement TV area most systems ( the Filtrete Ultra do. Not the case, this have opposite effect ok and he said they were probably doing it reduce. Right size for HVAC system no different than using 1-2 '' filter which is done frequently more.
2020 why does my central air have two filters