Annual filter changes?

MTC

I'm a landlord, and learned long ago to never trust tenants to maintain the air filters on the gas furnaces/AC air handlers, so I do it myself. I generally use FPR5 (about MERV8) 1" filters that fit the existing filter slots on my furnaces. Looking to do better than the cheapo dead cat catchers, but not trying to provide super high grade air quality for my tenants.

I'm looking to change things up a bit, at least when I am already having a furnace swapped out - but might just convert them all to simplify my life. My goals are:

1. Decent (but not excessive) filtration for tenant and to protect equipment from build up

2. Annual replacement, as I do it for all my units to make sure it gets done, and want to simplify my maintenance.

3. Low static pressure drop to prolong life of equipment.

4. Relatively easily accessible and not crazy expensive media replacements. Don't mind ordering them online.

I think something like Merv 8, or maybe as high as 11, 4-5 inch media, and oversizing it to give even more filtration area to extend lifespan/reduce static drop as the months go on. Would get at least as good, if not better, filtration than I have been. If my furnace would normally have say a 16x25x1 filter and it gets replaced about every 3 months, and I go to a 20x25x4.5ish (thinking Honeywell F100 line), that would be about 25% more surface area on the nominal size, plus more than 4x on the thickness… should get me safely to a year, right? That should also be a huge static pressure drop when new, and still quite good at end of filter life. I pay about $20/year now for the cheap filters - I can get these Honeywell for $26/ea in 5 packs, or the FilterBuy version for about $22/ea if I buy 6 at a time - so cost is plenty close enough, but I only have to do 1/4 of the filter changes, and my time has value. Also, standardizing filter size to this larger filter would just make life easier.

Does this seem about right to you guys? I'd have to buy the new filter frames, and have the ductwork customized to make it all fit, but that one time cost would be worth it to me to meet the above goals.

Any different media filtration systems you think are a better option for these goals?

HVACNUT

Middle of the road would be a 4 inch Merv 8. A high Merv would be too restrictive without oversizing and duct modifications. Not just to accept the filter cabinet, the whole duct system.

ECM or PSC blower motors?

It's nice that your thinking about your tenants air quality but do they have a qualified tech who will show up at 2 am in February when there's no heat?

leonz

Don't your tenants deserve cleaner air?

How many air changes occur per hour?

Why not just keep your air cleaner to begin with more frequent filter changes and better media to begin with to keep your tenants happier and provide healthier air?

How often do you have the air ducts video inspected, vacuum cleaned, scraped and or treated with ultra violet light?

By the time you change the filter frame size and deal with the cost of labor and additional sheet metal cost and air flow differences-meaning slower air speed at the filter you would have paid for in plenum humidifiers or portable floor model humidiers for each tenant, better air filters and Dwyer Mark II air meter guages mounted on a wall near the furnaces and away from the combusition chamber and Dwyer plenum probes placed in the air stream in the intake plenum and postive pressure gradient plenum of each furnace to monitor air flow velocity/pressure gradients before and after the filter media to tell you when the filters need to be changed.

Having a larger plenum fan installed has its share of problems with smaller ducting.

I grew up with forced air heat in my later growing up years and I hated it because of the dust and sinus trouble.

My thoughts as a homemowner.

STEVEusaPA

I just go over and change them myself. Simple cheap filters. The filters only job in these cases is to protect the blower/blower wheel. Not my job to provide purified air as a landlord. Then can plug in their own appliance that they think may work magic for them.
Don't think, or let anyone tell you, a better filter 'cleans' or 'purifies' the air. That's a whole different set up.

leonz

From my experience as a homeowner the older Orec Air Cleaners work very well and provide cleaner air by moving it through the eletrostatic precipitator grid in the air cleaners air flow along with the ozone generator.

The original Orec Design had a very thick blue fiber prefilter that cleaned the air of particulates before the air flow passed through the electrostatic precipitator grid in the housing.

JUGHNE

As a landlord for about 40 years, I see an advantage to changing/checking the air filters myself, often monthly.

This gives you a legitimate reason to visit and inspect your investment property.

If the tennents know that you might show up monthly the place may be cleaned up a little more often.

Walking thru the unfinished basement lets you check for leaking plumbing from above.

Some will not report a drip under a sink or WC, thinking the landlord will blame them for it.

There have been surprises.😮

leonz

My brothers have good tenants and have no issues and they take care of whatever needs to be taken care of.

MTC

https://forum.heatinghelp.com/discussion/comment/1744459#Comment_1744459

Yeah, I've been looking at the Honeywell F100 cabinets, which are 4 3/8" actual - sometimes called 4, sometimes called 5". Standard 1" filters are usually about 3/4" actual, so that alone should be almost 6x the surface area, assuming same number of pleats (but I think the 4" media does have fewer pleats, so probably not quite that much improvement). Wish they would all publish the total surface area of filtration and a static pressure drop to compare with others…

The F100 cabinet comes with a MERV 11, but I'd probably go to 8 with replacements to keep static drop under control and extend life between changes. I do have a manometer, so might just monitor static conditions a bit and test it out with the 11 and see from there. The cost difference between the 8 and 11 is almost nothing, so if it holds up well for a year w/o much additional pressure drop, could be worth keeping with the 11. Given that I have 1" MERV 8 filters now that should probably be changed monthly, but in reality its more like quarterly, that should be a big improvement to static pressure on its own. If I can also increase the filter size from 16x20 and 16x25 on a number of them, up to 20x25, I'll also gain a ton of surface area there, so should be at minimum about 6x the total surface area of what I'm currently doing.

Not sure if they're all ECM motors yet, but def the newer ones. As older ones get replaced, will certainly become ECM. Its more likely that I would have this change done during a furnace swap anyway - need to swap at least one this spring, so trying to figure that

As I said, I'm looking to provide decent air quality, not go crazy. I also want to keep my fans and coils from clogging up with dust, so it seems like MERV 8-11 is reasonable without going crazy. If I already have to tear apart the ductwork and reconfigure it to fit a new housing, might as well upsize it at the same time. The media is about the same cost for smaller or larger sizes within the 4", so why not. If its done right, it should make the system more reliable, not less - hence me trying to make sure my plan will actually accomplish this goal. I might consider doing it and swapping every 6 months instead if it seems like its necessary, but my goal is to have a filter that can last a year for an apartment without pets, smokers, etc (almost all of mine, other than a couple inherited tenants that are still here). My units are very nice, and my tenants generally take care of them well, so I'm less concerned with abuses, and more willing to offer better than absolute minimum for them on things like air quality - without going overboard.

MTC

https://forum.heatinghelp.com/discussion/comment/1744473#Comment_1744473

I'm generally an overly generous landlord, but this is just sillyness. What I'm trying to provide is far better than most homeowners have. Do you think said tenants want to pay me more for providing exceptional level air quality?

Keep what air cleaner? They currently have a crappy 1" filter like most houses. I would be making their situation better than the already higher than most provide standard I'm giving them.

You seem to have bought into a bunch of snake oil there.

If you have people who can provide all those services for the few hundred that this would cost, please send me their contact info.

There would be no larger fan, just a larger media cleaner, which would slow the velocity through the filter and reduce the hit to static pressure. All of that is a good thing for both equipment and tenant. It also helps make up for often inadequate duct sizing, as the filter is often as much static pressure loss as the entire ducting system.

MTC

https://forum.heatinghelp.com/discussion/comment/1744481#Comment_1744481

Yeah, I do too, just looking to not have to do it as often, while also easing the stresses on the equipment, etc. Also, I have a vacation rental that is 8 hours away, and the managment costs are kind of stupid high, so if I could just swap it annually when we visit, that would be ideal.

I don't mind providing a little better air if cost isn't crazy and if its also helping to prevent build up issues on my blower, AC coil, etc. MERV 8 to 11 seems to be decent for that - they can add air purifiers as they desire, like you say. I run a room HEPA purifier in our living room at my house, as our heat is radiant floors and the extra filtration in winter is nice.

MTC

https://forum.heatinghelp.com/discussion/comment/1744599#Comment_1744599

I can see that reasoning. I do try to stop by at least every couple months and take a look around the basement/common areas. All of my local properties I can do that w/o any notice to the tenants, so I just do it on a whim. I do also have a couple vacation rentals out of state, one with a forced air system… I'd like to just swap the filter, flush water heater out, do a pest treatment, etc quickly once a year when I visit there, rather than rely on my local managment to actually get these things done.

My tenants are generally pretty high end, and my units are mostly completely redone with new plumbing, etc, so not usually too many surprises and they will usually tell me if anything is off. But I do agree it's good plan to stop by and check periodically…

MTC

https://forum.heatinghelp.com/discussion/comment/1744668#Comment_1744668

Agree with the general idea that it's not my responsibility to provide hospital grade air quality to tenants. Also do not agree with your general attitude towards tenants. Most of that is your choice as a landlord - where you buy properties, how well you update and maintain them, how well you screen your tenants, etc. I almost never have any issues like this, and generally have excellent tenants that love living in my units and don't want to leave - the vast majority that leave my units are getting married/moving in with significant other, buying a house, or moving out of town for work. Have had some move from one of my units to another to get larger space but not leave me as a landlord. You get out what you put in in this business.

MTC

https://forum.heatinghelp.com/discussion/comment/1745181#Comment_1745181

Your description only confirms my point. I have many landlord friends/associates, and have seen some things. In almost every case, I can point to where the landlord went wrong when something crazy like this comes up, plus a few just silly things that tenants didn't know any better but were trying. And my landlord friends who operate more like I do, much like me, have almost zero problems like this.

That's not to say you can spend infinitely and expect a return - of course not. But you do get back based on what you put in, and I can tell from your pictures, the way you talk about tenants, the things you expect of them, and the results you're getting, that you do not operate anything like I do. Your choice, but a lot of those results are things you should have expected rather than just complaining about the poor tenants you put in your places.

Anywhoo, I'm not providing crazy air filtration. I'm providing decent, better than average for a rental. And I'm looking to benefit myself and prolong my equipment life as well. Much more interested in productive input on my proposed plan than a tirade against tenants… anyone have more input on that?

GGross

@MTC

I am not sure if the larger/thicker filters would need replacing less often. In my experience I replace them at similar intervals to the thinner ones. I think some of the concern that a few might have with putting in thicker filters is that they are by default just a bit more restrictive to airflow, and so if they are not changed out in a timely manner they could get plugged a bit and cause your furnace some problems. I think that either route you take you are doing a great job. I used to rent from someone who refused to do any upkeep, and tried to bill me for the lack of maintenance when we moved out, so you are already leaps and bounds above many.

I would maybe add that the thinner filters, being overall less expensive, would make it cheap enough you could change them out more often, which could be seen as a benefit since minor issues can often go unnoticed and the more you get to see the property the more likely you may be to see an issue before it becomes a problem. But if you are able to get the thicker ones at a reasonable price, maybe you can stop by for a filter inspection the first year instead, to determine the correct interval to change your new filters

Thanks for being an active involved landlord, and sorry to see your thread get derailed here

Larry Weingarten

Hi @MTC , Hopefully I'm not derailing things, but have you looked into electrostatic air filters? Here's a site that compares HEPA and electrostatic without a bias, as they make both types. An interesting thing they found was far less initial pressure drop with electrostatic, and the unit can just be cleaned rather than replaced. https://www.lakeair.com/hepa-vs-electrostatic/#:~:text=The HEPA Air purifier in the Maxum has,it and therefore has a lower pressure drop.

Yours, Larry

EdTheHeaterMan

Annual filter changes?

was the title of this post, and it struck me as being a little sarcastic. I don't know of any air filter that recommends anything less than 2 times a year, most are on a monthly or 90 day recommendation. So My question to @MTC is, Why do you want to do it once a year? Sounds like every other year might be OK if you can get a large enough filter in there. All you need is to get a 1000 ft roll of filter paper and connect it to a motor with a reduction gear. Have the paper connected to a paper shredder on the receiving end of the filter as it rolls out a little over 1 foot per day. A new sheet of Merv 8 daily would be most efficient

MTC

GGross said:

@MTC

I am not sure if the larger/thicker filters would need replacing less often. In my experience I replace them at similar intervals to the thinner ones. I think some of the concern that a few might have with putting in thicker filters is that they are by default just a bit more restrictive to airflow, and so if they are not changed out in a timely manner they could get plugged a bit and cause your furnace some problems. I think that either route you take you are doing a great job. I used to rent from someone who refused to do any upkeep, and tried to bill me for the lack of maintenance when we moved out, so you are already leaps and bounds above many.

I would maybe add that the thinner filters, being overall less expensive, would make it cheap enough you could change them out more often, which could be seen as a benefit since minor issues can often go unnoticed and the more you get to see the property the more likely you may be to see an issue before it becomes a problem. But if you are able to get the thicker ones at a reasonable price, maybe you can stop by for a filter inspection the first year instead, to determine the correct interval to change your new filters

Thanks for being an active involved landlord, and sorry to see your thread get derailed here

I think you may be referring to something different than I am. Thicker filters of the same MERV rating offer drastically lower pressure drop and have drastically more filter area to allow for longer life with less pressure drop than thinner ones. Rough math - assuming same number of pleats (which is not usually the case, but just for simplicity sake), a nominal 1" filter is about 3/4" thick. The Honeywell F100 media is 4 3/8" thick. If same number of pleats, that would be almost 6x the filter area with no increase in air flow, contamination, etc, nor is the filter more restrictive.

I'm also looking to standardize my filter size up to a 20x25. Most of my furnaces currently have 16x20, 16x25, and I think one is already 20x25. So that increase in size at the filter would add a lot more media, while also slowing down the airflow rate since its going through a larger cross section of duct at that point, reducing pressure drop even further and extending life before clogging that much more.

I get the point of monthly-ish inspections. I do try to stop by my properties fairly often, but I have a couple of scenarios. My local ones I pop in a little more often, but often 3-4 months might go by, which the little 1" filters are not great for that. I have pretty great apartments which attract pretty great tenants, and for the most part, they're really good about letting me know if anything is off. The other scenario I have, and one of the places I really want to try to make this work, is a vacation rental I have 8 hours drive away. I'm usually there once a year over my kids spring break, and our management company is crazy expensive for general maintenance stuff. If I could get that one down to 1 change per year, or maybe 2, then I could do the one change, along with a bunch of other annual basic maintenance stuff for a few hours every year when I'm already there. If it seems like it needs more than that, could have the management do it once in the fall. Either way, should be getting really solid filtration and keeping the pressure drop way lower to protect the expensive HVAC equipment there, with minimal hassle/cost.

MTC

Larry Weingarten said:

Hi @MTC , Hopefully I'm not derailing things, but have you looked into electrostatic air filters? Here's a site that compares HEPA and electrostatic without a bias, as they make both types. An interesting thing they found was far less initial pressure drop with electrostatic, and the unit can just be cleaned rather than replaced. https://www.lakeair.com/hepa-vs-electrostatic/#:~:text=The HEPA Air purifier in the Maxum has,it and therefore has a lower pressure drop.

Yours, Larry

Hi Larry,

I have experimented with them a bit in the past. And I have one in my own home. I find the process of cleaning them a little more arduous than I expected (its not bad, but enough that even at home, I tend to put it off far too long - will be even worse at the apartments). Also, I'm not looking for HEPA air cleaning, just a decent degree of filtration with low pressure drop, and easy maintenance. So, if I was able to retrofit all the furnaces with the same 20x25x5 media cabinets, I could order a set of them in bulk, drive around while doing other routine maintenance on all the units, and swap them all in seconds. Save on purchase by buying all same size in quantity from Filterbuy, and just easier for me overall.

I do agree that if you're looking for really high level air cleaning, electrostatic is probably the way to go, but not sure that it works well for my specific goals in this case.

MTC

EdTheHeaterMan said:

Annual filter changes?

was the title of this post, and it struck me as being a little sarcastic. I don't know of any air filter that recommends anything less than 2 times a year, most are on a monthly or 90 day recommendation. So My question to @MTC is, Why do you want to do it once a year? Sounds like every other year might be OK if you can get a large enough filter in there. All you need is to get a 1000 ft roll of filter paper and connect it to a motor with a reduction gear. Have the paper connected to a paper shredder on the receiving end of the filter as it rolls out a little over 1 foot per day. A new sheet of Merv 8 daily would be most efficient

Despite your sarcasm, I'll respond in seriousness. The very Honeywell filters I'm talking about here, say they are rated for up to 12 months. And that is assuming you have it sized normally to the furnace. If you were to take a furnace that operates with a 16x20x1 filter and put in a 20x25x5 filter, you have increased the cross sectional area of the duct at the filtration point by over 50%, which means even a 1" filter would be operating with more than 50% more filtration surface area, plus the velocity through the filter would drop significantly, which reduces pressure drop even more than just the extra surface area. Then multiply that by almost 6 (using simplified assumption of same number of pleats - which to be fair is usually not the case) for the added thickness. So we're at about 9x there, without even factoring the reduction in air velocity, which is a substantial effect. I don't know how to do that math, but probably gets you up to about 12x with that factored in. Apply this to your original filter with anywhere from 1-3 month rated life, and annual doesn't seem so far fetched.

Compare to Honeywell saying their 16x20x5 model lasts up to 12 months (would assume ideal conditions, no pets, etc), and apply the more than 50% increase by going up to 20x25, and then apply the reduction in air velocity, and under reasonable conditions, it seems like 12 months is viable.

lkstdl

MTC, you are on the right track with the larger filter area. From the Energy Vanguard article The Path to Low Pressure Drop Across a High-MERV Filter:

Filter Area = 2.0 square feet (or more) for each 400 cfm of air flow.

You can also use return filter grilles, in which the filter lives at the start of the returns rather than in the plenum just before the furnace, making it easy to double or triple your filter area. Could be a good solution if there's not much space by the furnace. I haven't seen them in 4" depth though.

For the fan coils in our artist studios, we actually use 4 separate (in parallel) 20x20x4 MERV filters. The additional ducting and filter holders is a one time cost, and if it lets us run quieter and with less fan energy and more leeway as filters start to clog, in my mind its a good investment.

pecmsg

The filter in your system is to protect the system, not replace the vacuum cleaner. 

If you do not want to change it monthly get a 5” media filter Properly installed in the return duct. 

ChrisJ

pecmsg said:

The filter in your system is to protect the system, not replace the vacuum cleaner. 

If you do not want to change it monthly get a 5” media filter Properly installed in the return duct. 

My system actually has filter grills, with no filters in them.
I originally planned on two 12x12x1 filters, a 10x10x1 filter and a 14x30x1 filter. Some time during this, I realized the pressure drop across 1" filters and decided to shoehorn a AirBear 25x20x5 in by the air handler.

Sometimes the 20x25x5 filter lasts all summer. Sometimes it doesn't.
But, I have no doubt it was a better move than all of the smaller 1" filters as far as pressure drop. I also didn't like how the filter grills had openings all over where air would bypass the filter with no easy solution.

leonz

Hello ChrisJ,

I have mentioned this previously, but investing in a pair of Dwyer Mark II Manometers with the Dwyer probes mounted near the furnace to monitor the forced draft air flow before the air filter and a second Dwyer Mark II Manometer with a Dwyer probe after the filter will tell you immediately when a filter needs to be changed as the air pressure in in front of the filter will be greater and after the filter the air pressure will be lower.

By just looking at the water pressure reading you will know what condition your air filters are in.

ChrisJ

leonz said:

Hello ChrisJ,

I have mentioned this previously, but investing in a pair of Dwyer Mark II Manometers with the Dwyer probes mounted near the furnace to monitor the forced draft air flow before the air filter and a second Dwyer Mark II Manometer with a Dwyer probe after the filter will tell you immediately when a filter needs to be changed as the air pressure in in front of the filter will be greater and after the filter the air pressure will be lower.

By just looking at the water pressure reading you will know what condition your air filters are in.

I have a Dwyer Magnehelic plumbed in.

And honestly, for this application you do not need the probes. Any fitting will get more than close enough of a reading since you're going by change rather than an actual number.

While I have a 0-1" Magnehelic plumbed across the entire air handler + filter, A 0-.05" one plumbed just across the air filter would work fantastic and I see no need for two manometers for this application.

leonz

I was only going by what the Dwyer people mentioned in using 2 of them.

ethicalpaul

Well they do sell manometers after all LOL

MTC

lkstdl said:

MTC, you are on the right track with the larger filter area. From the Energy Vanguard article The Path to Low Pressure Drop Across a High-MERV Filter:

Filter Area = 2.0 square feet (or more) for each 400 cfm of air flow.

You can also use return filter grilles, in which the filter lives at the start of the returns rather than in the plenum just before the furnace, making it easy to double or triple your filter area. Could be a good solution if there's not much space by the furnace. I haven't seen them in 4" depth though.

For the fan coils in our artist studios, we actually use 4 separate (in parallel) 20x20x4 MERV filters. The additional ducting and filter holders is a one time cost, and if it lets us run quieter and with less fan energy and more leeway as filters start to clog, in my mind its a good investment.

Thanks Luke, this is helpful. Got me down a rabbit trail of energy vanguard articles, once again. Been down that road many times, haha.

I struggle with their assertion that you just use the nominal area of the filter. I could maybe see this in terms of initial pressure drop, if that's your only concern, but it can't hold up like that for long. Surely that 1" and 4" thick filter that might not have a big initial pressure drop difference are going to be an entirely different story quite quickly. And I guess that's ok if you plan to replace monthly, but I'm not sure that many people are consistent about that. So I'd like to see the same comparision, somehow fairly done after a certain amount of loading, or after being exposed to exact same conditions for its rated lifespan, etc. This would probably need to be done in a controlled lab-like setting to get any accuracy. Then we could look at both of those numbers and get some sort of average pressure loading on the system. Going only on initial drop seems short sighted to me, particularly as someone interested more in low maintenance/longevity than in high performance filtration.

2 sq ft per ton (in AC terms) seems difficult for a normal home system. One of the properties I'm looking at doing this filter change on (the next one, so most focus on it right now), has a 2.5 ton AC. Its probably oversized, but the return ducting does not go to the 2nd floor, so the system has other problems to overcome... Using the 400cfm/ton estimate, that means I need 2.5 x 2sq ft, or 5 sq ft of nominal filter area. I could see that on a 1" filter, but seems excessive on a 5" (4 3/8" actual, based on the proposed Honeywell F100 media). In heating mode, the new furnace going in is 1200cfm max flow, so even worse. 6 sq ft of filter is hard to achieve at the furnace in most installations. And this isn't a big house...

This particular house has floor returns, so don't think filters there would work out well... too much junk falling on them, and it would look terrible through the return grills, if you could figure out a good way to mount them in there in the first place. Several of my other rentals also have floor returns - common in my area with lots of older homes that were usually later retrofitted with forced air.

I might consider converting my home ducted mini split to this, but I do have 4 returns in it, so not overly simple. One of them is also quite high, over a stairwell, so access would be challenging.

I do have another place in mind for this kind of upgrade in the near future, where it might be the best solution (one large, easily accessible return grill. I'll have to look more into filter grill options for that place. I was gearing up to redo the main return trunk to make room for an F100 or similar... this might be sufficient instead and easier, but not sure if there's enough depth to not restrict air flow in the process. I'll take a look next time I'm down there.

MTC

pecmsg said:

The filter in your system is to protect the system, not replace the vacuum cleaner. 

If you do not want to change it monthly get a 5” media filter Properly installed in the return duct. 

That is precisely what I'm suggesting, just looking at ways to extend its life even further for ease of maintenance across numerous rentals. If I go oversized and 5" thick, trying to determine if its feasible to get filter life of 1 year under normal (no pets, smoking inside, etc) circumstances. Seems feasible if done right.

MTC

ChrisJ said:

pecmsg said:

The filter in your system is to protect the system, not replace the vacuum cleaner. 

If you do not want to change it monthly get a 5” media filter Properly installed in the return duct. 

My system actually has filter grills, with no filters in them.
I originally planned on two 12x12x1 filters, a 10x10x1 filter and a 14x30x1 filter. Some time during this, I realized the pressure drop across 1" filters and decided to shoehorn a AirBear 25x20x5 in by the air handler.

Sometimes the 20x25x5 filter lasts all summer. Sometimes it doesn't.
But, I have no doubt it was a better move than all of the smaller 1" filters as far as pressure drop. I also didn't like how the filter grills had openings all over where air would bypass the filter with no easy solution.

I'd be curious as to your actual results if you tried swapping to the 3) 1" filters. If it is indeed true that initial pressure drop isn't much different on a thicker filter than a thinner one, then in theory, you should have less drop with the like 25% greater surface area of the 3 filters. But they'd plug up faster and need to be replaced often, or the drop would quickly become worse.

The large amount of air gaps in the filter grills is an interesting point. They do seem to be a lot leakier than a good media filter at the furnace.

ChrisJ

MTC said:

ChrisJ said:

pecmsg said:

The filter in your system is to protect the system, not replace the vacuum cleaner. 

If you do not want to change it monthly get a 5” media filter Properly installed in the return duct. 

My system actually has filter grills, with no filters in them.
I originally planned on two 12x12x1 filters, a 10x10x1 filter and a 14x30x1 filter. Some time during this, I realized the pressure drop across 1" filters and decided to shoehorn a AirBear 25x20x5 in by the air handler.

Sometimes the 20x25x5 filter lasts all summer. Sometimes it doesn't.
But, I have no doubt it was a better move than all of the smaller 1" filters as far as pressure drop. I also didn't like how the filter grills had openings all over where air would bypass the filter with no easy solution.

I'd be curious as to your actual results if you tried swapping to the 3) 1" filters. If it is indeed true that initial pressure drop isn't much different on a thicker filter than a thinner one, then in theory, you should have less drop with the like 25% greater surface area of the 3 filters. But they'd plug up faster and need to be replaced often, or the drop would quickly become worse.

The large amount of air gaps in the filter grills is an interesting point. They do seem to be a lot leakier than a good media filter at the furnace.

If you look at an air bear filter and the housing they sell it has foam gaskets.
Each filter comes with new gaskets on two sides. The bottom I don't think has any as it just sits flush, but the lid has a beef foam gasket.

I'd expect a new 5" filter to have less drop than a new 1" filter as there's a lot more media to pass through because it's corrugated. If that's the proper term.....

MTC

ChrisJ said:

MTC said:

ChrisJ said:

pecmsg said:

The filter in your system is to protect the system, not replace the vacuum cleaner. 

If you do not want to change it monthly get a 5” media filter Properly installed in the return duct. 

My system actually has filter grills, with no filters in them.
I originally planned on two 12x12x1 filters, a 10x10x1 filter and a 14x30x1 filter. Some time during this, I realized the pressure drop across 1" filters and decided to shoehorn a AirBear 25x20x5 in by the air handler.

Sometimes the 20x25x5 filter lasts all summer. Sometimes it doesn't.
But, I have no doubt it was a better move than all of the smaller 1" filters as far as pressure drop. I also didn't like how the filter grills had openings all over where air would bypass the filter with no easy solution.

I'd be curious as to your actual results if you tried swapping to the 3) 1" filters. If it is indeed true that initial pressure drop isn't much different on a thicker filter than a thinner one, then in theory, you should have less drop with the like 25% greater surface area of the 3 filters. But they'd plug up faster and need to be replaced often, or the drop would quickly become worse.

The large amount of air gaps in the filter grills is an interesting point. They do seem to be a lot leakier than a good media filter at the furnace.

If you look at an air bear filter and the housing they sell it has foam gaskets.
Each filter comes with new gaskets on two sides. The bottom I don't think has any as it just sits flush, but the lid has a beef foam gasket.

I'd expect a new 5" filter to have less drop than a new 1" filter as there's a lot more media to pass through because it's corrugated. If that's the proper term.....

I totally agree. I was referring to some of the info in the links provided above, that say that initial drop is actually not much different between similar filters of the same size, but different thicknesses. I find that hard to believe, but it is apparently true. I'd still opt for thicker for less maintenance... but if that is true, the 1" filters with about 25% greater nominal surface area should actually provide lower initial static drop. Doubt it would hold up long, and who wants to change 3 filters every month?

I'm considering the Honeywell, which might not be quite as air sealed, but still looks fairly tight. How did you end up picking the Air Bear?

ChrisJ

MTC said:

ChrisJ said:

MTC said:

ChrisJ said:

pecmsg said:

The filter in your system is to protect the system, not replace the vacuum cleaner. 

If you do not want to change it monthly get a 5” media filter Properly installed in the return duct. 

My system actually has filter grills, with no filters in them.
I originally planned on two 12x12x1 filters, a 10x10x1 filter and a 14x30x1 filter. Some time during this, I realized the pressure drop across 1" filters and decided to shoehorn a AirBear 25x20x5 in by the air handler.

Sometimes the 20x25x5 filter lasts all summer. Sometimes it doesn't.
But, I have no doubt it was a better move than all of the smaller 1" filters as far as pressure drop. I also didn't like how the filter grills had openings all over where air would bypass the filter with no easy solution.

I'd be curious as to your actual results if you tried swapping to the 3) 1" filters. If it is indeed true that initial pressure drop isn't much different on a thicker filter than a thinner one, then in theory, you should have less drop with the like 25% greater surface area of the 3 filters. But they'd plug up faster and need to be replaced often, or the drop would quickly become worse.

The large amount of air gaps in the filter grills is an interesting point. They do seem to be a lot leakier than a good media filter at the furnace.

If you look at an air bear filter and the housing they sell it has foam gaskets.
Each filter comes with new gaskets on two sides. The bottom I don't think has any as it just sits flush, but the lid has a beef foam gasket.

I'd expect a new 5" filter to have less drop than a new 1" filter as there's a lot more media to pass through because it's corrugated. If that's the proper term.....

I totally agree. I was referring to some of the info in the links provided above, that say that initial drop is actually not much different between similar filters of the same size, but different thicknesses. I find that hard to believe, but it is apparently true. I'd still opt for thicker for less maintenance... but if that is true, the 1" filters with about 25% greater nominal surface area should actually provide lower initial static drop. Doubt it would hold up long, and who wants to change 3 filters every month?

I'm considering the Honeywell, which might not be quite as air sealed, but still looks fairly tight. How did you end up picking the Air Bear?

I honestly don't remember.
I think it was at Supplyhouse.com and seemed like a lot of people liked their products so I went with it.

Though, I honestly thought the initial pressure drop ratings on a 1" thick MERV 8 were much higher than a 5" thick MERV 8.

Larry Weingarten

Hi @MTC , As you mentioned Energy Vanguard, how about writing Allison Bailes and asking for/suggesting a blog post on this topic? Share this thread. He's a very thorough researcher and sees things that others may miss. Then you can school all of us!

Yours, Larry

MTC

ChrisJ said:

MTC said:

ChrisJ said:

MTC said:

ChrisJ said:

pecmsg said:

The filter in your system is to protect the system, not replace the vacuum cleaner. 

If you do not want to change it monthly get a 5” media filter Properly installed in the return duct. 

My system actually has filter grills, with no filters in them.
I originally planned on two 12x12x1 filters, a 10x10x1 filter and a 14x30x1 filter. Some time during this, I realized the pressure drop across 1" filters and decided to shoehorn a AirBear 25x20x5 in by the air handler.

Sometimes the 20x25x5 filter lasts all summer. Sometimes it doesn't.
But, I have no doubt it was a better move than all of the smaller 1" filters as far as pressure drop. I also didn't like how the filter grills had openings all over where air would bypass the filter with no easy solution.

I'd be curious as to your actual results if you tried swapping to the 3) 1" filters. If it is indeed true that initial pressure drop isn't much different on a thicker filter than a thinner one, then in theory, you should have less drop with the like 25% greater surface area of the 3 filters. But they'd plug up faster and need to be replaced often, or the drop would quickly become worse.

The large amount of air gaps in the filter grills is an interesting point. They do seem to be a lot leakier than a good media filter at the furnace.

If you look at an air bear filter and the housing they sell it has foam gaskets.
Each filter comes with new gaskets on two sides. The bottom I don't think has any as it just sits flush, but the lid has a beef foam gasket.

I'd expect a new 5" filter to have less drop than a new 1" filter as there's a lot more media to pass through because it's corrugated. If that's the proper term.....

I totally agree. I was referring to some of the info in the links provided above, that say that initial drop is actually not much different between similar filters of the same size, but different thicknesses. I find that hard to believe, but it is apparently true. I'd still opt for thicker for less maintenance... but if that is true, the 1" filters with about 25% greater nominal surface area should actually provide lower initial static drop. Doubt it would hold up long, and who wants to change 3 filters every month?

I'm considering the Honeywell, which might not be quite as air sealed, but still looks fairly tight. How did you end up picking the Air Bear?

I honestly don't remember.
I think it was at Supplyhouse.com and seemed like a lot of people liked their products so I went with it.

Though, I honestly thought the initial pressure drop ratings on a 1" thick MERV 8 were much higher than a 5" thick MERV 8.

Gotcha, yeah Supplyhouse is decent. They sell a bunch of brands of media air cleaners. I wish there was more real data out there about pressure drops across filters, and then a standardized way to test them for pressure drop at a set loading point, so we could make better decisions as consumers.

I did too... and kinda still do, TBH. But Allison Bailes is very respected, so if he's claiming that studies show not a drastic difference in general, on initial pressure drop... have to believe there's something to it. I still would choose the thicker media just for longevity and easier maintenance. There's no way a 1" doesn't plug up much faster than a 5" using same basic filter media... and thereby have higher pressure drop when loaded.

MTC

Larry Weingarten said:

Hi @MTC , As you mentioned Energy Vanguard, how about writing Allison Bailes and asking for/suggesting a blog post on this topic? Share this thread. He's a very thorough researcher and sees things that others may miss. Then you can school all of us!

Yours, Larry

Not a bad idea. I might just have to do that.

JakeCK

All this talk of furnace air filters and such while I'm sitting over here like this:

lkstdl

Take a look at the test data (attached) -- these are from FilterBuy.com.
It only shows initial, not 'aged'.
You can see that the total media area doesn't increase linearly with depth because the pleat count decreases.
In this particular case the 4" has just 21% more filter media than the 2".
Maybe there is a market opportunity for someone to offer a 4" filter with a higher pleat count?

ChrisJ

lkstdl said:

Take a look at the test data (attached) -- these are from FilterBuy.com. It only shows initial, not 'aged'. You can see that the total media area doesn't increase linearly with depth because the pleat count decreases. In this particular case the 4" has just 21% more filter media than the 2". Maybe there is a market opportunity for someone to offer a 4" filter with a higher pleat count?

Those are also MERV 13 which has no business on any residential system.

Do they have numbers on MERV 7 or 8 and how does a 1" compare to a 4"?

JakeCK

ChrisJ said:

Those are also MERV 13 which has no business on any residential system.

Do you have any data or sources to backup that claim?

dko

JakeCK said:

ChrisJ said:

Those are also MERV 13 which has no business on any residential system.

Do you have any data or sources to backup that claim?



NAFA application guide. Merv 13 is just overkill requiring more frequent changes for general residential use.

But since COVID, organizations including ASHRAE are recommending to install minimum MERV 13. I mean, they do have to cover their butts too.

JakeCK

That is an incomplete chart of the performance of various merv levels.

https://www.epa.gov/indoor-air-quality-iaq/what-merv-rating

12

0.30-1.0 greater than or equal to 35%

1.0-3.0 greater than or equal to 80%

3.0-10.0 greater than or equal to 90%

13
0.30-1.0 greater than or equal to 50%

1.0-3.0 greater than or equal to 85%

3.0-10.0 greater than or equal to 90%

Now let me tell you something about allergies, which I suffer from. Many of the things that can set off allergic reactions are smaller than 2 microns, and the smaller they are the deeper they can penetrate into the body. For example pollen can range from 200 microns to as small 2 microns, pet dander is generally 2.5 to 10 microns but both can be considerably smaller once they have had time to break down in the environment. And then there is all the crap in the air that we breath that is in the inner cities. Cleveland is an old rust belt city, you know the city that is known for a burning river despite not being the only polluted city that had river fires. And that stuff is still around in the air, soil, and water...
In the warmer months when I can have the windows open I put a couple of box fans blowing in with a single 1" merv 13 20x20" filter on them, this actually pressurizes the house enough that I can feel warm air on a cool night pushing out of cracked open windows downstairs. And then there is the large four filter fan. Look up Corsi-rosenthal filter, it can outperform a HEPA filter for a fraction of the cost. Running these makes the difference between eating Claritin for 4-5 months of the year and walking up being able to breath with out drugs. There is also the benefit that when my 5 year old brings something home from school it reduces the chance of him giving it to everyone in the house, considerably. And when COVID protocols were in effect at work it mean't I didn't burn all of my PTO because of the sniffles.