Thoughts on air filters...

[EOC_Jason]

I was going to get some replacement air filters (just standard 1") since Sam's had some nice Filtrete 1200D 4-packs with an $8 discount... Was comparing price against the usual Filtrete 1085 ones I get at Lowe's...

Of course I started going down the rabbit hole comparing other brands, then reading discussions about air flow restriction, etc, etc... Came across a post mentioning these beauties made by Honewell.

Honeywell (and other brands) make a 3-4" deep filter that will fit in a normal return air grill, assuming you have enough space behind the filter (which I have tons, I measured everything to make sure)....

Looking around I found Accumulair branded models for ~$30 each. Supposedly those are made in the USA.

Anyone have anything positive / negative to say about that style or brand?

Figure if there is no downside I will pull the trigger and get me a pair for my return air grates before I start using the A/C in the summer...

 

[Done That]

I've used 4" media filters for years and really like them. I only need to change mine about every 9 months. Mine go into a metal filter box on the air handler return air, but same idea.

I personally try to stick with about a MERV 10 filtration level, as higher can become too restrictive very quickly and impact the system.

I don't know that brand off hand but doubt you'll go too far afield giving them a try...

 

[yeldogt]

The 4" MERV 11 filters IMO are ideal for new equipment w/ direct drive motors .... especially VS. It's really about protecting the equipment and -- doing some air cleaning.

The old 1" fiberglass are really for belt driven high flow low static oil furnaces -- designed to keep the big stuff out. Many of the 1" High MERV pleated can be very restrictive.

Depending on the house I switch them every 6 months to a year

 

[mrpizza]

I have an air bear box on my system, takes a 20x20x5 media filter. They are good for up to 6 months as the surface area of the filter media is so much greater.

 

[trashmanssd]

I buy 12 packs of Glasfloss MERV 11 filters from amazon. I change my filters every 3 weeks to 2 months depending on how much the system is being used. In the middle of winter or summer I change it every 3 weeks to keep the air flow up when the systems running alot. During spring and fall the system barley runs so I will go 2 months. All in all I go through a 12 pack every year and it cost me 60$ per air handler usually. I also keep a few real cheap fiberglass ones that just catch the big stuff but flow a ton of air for the winter in case we have an arctic blast i will throw one those in for a week to up the air flow to help the system get through those times easier.

 

[2Big2Ride]

Never seen a stepped filter like that, that looks like a great solution to get more filter material into the return air stream. Thanks for sharing.

 

[Crossfire05]

The 4" MERV 11 filters IMO are ideal for new equipment w/ direct drive motors .... especially VS. It's really about protecting the equipment and -- doing some air cleaning.

The old 1" fiberglass are really for belt driven high flow low static oil furnaces -- designed to keep the big stuff out. Many of the 1" High MERV pleated can be very restrictive.

Depending on the house I switch them every 6 months to a year

My two ceiling intakes (1st and 2nd floor) have very cheap 16 x 16 x 1 filters (brown cardboard frames). The frame only accepts a 1 inch depth of filter. What filter would be the best here?

 

[Trey T]

The typical 1" filter, in probably 99% of residential homes, is a double-edge sword. If your concern is dust or health, then you want to spend a lot of money on the high-end filters. However, that will increase the flow restriction (increase in static pressure) and likely to harm your equipment.

My rule of thumb is to get something that's priced in the middle (higher the price, the higher the flow restriction). Otherwise, many conscious HVAC tech will recommend the 4" version to get the best of both world.

I have the 1" and not the cheapest type filter. I'll upgrade to the 4" in the near future.

 

[Crossfire05]

The typical 1" filter, in probably 99% of residential homes, is a double-edge sword. If your concern is dust or health, then you want to spend a lot of money on the high-end filters. However, that will increase the flow restriction (increase in static pressure) and likely to harm your equipment.

My rule of thumb is to get something that's priced in the middle (higher the price, the higher the flow restriction). Otherwise, many conscious HVAC tech will recommend the 4" version to get the best of both world.

I have the 1" and not the cheapest type filter. I'll upgrade to the 4" in the near future.

Is the 4 inch somehow designed to fit in the old frame (where the 1 inch is) or does the frame actually have to be altered? Sounds like a lot of modification to the ceilings. What would be a middle of the road 1 inch? I wonder how effective any of these seal around the edges the way they are made.

 

[Trey T]

No, it can be major modification to the HVAC system. When retrofitting, the 1" filter grille will be left in place w/o any filter, then there will be another filter housing to be installed somewhere near the furnace blower (air handler).

 

[Crossfire05]

No, it can be major modification to the HVAC system. When retrofitting, the 1" filter grille will be left in place w/o any filter, then there will be another filter housing to be installed somewhere near the furnace blower (air handler).

Interesting! I looked at my furnace which is in a closet on the second floor. Looks like a problem doing that. Only 3 inches between the return and the furnace wall. See picture. My wife and I both have allergies and Utah is a dusty place (desert). It would be great to have well filtered air. I suppose under this situation the return air ducts get pretty dirty.

 

[Crossfire05]

I was going to get some replacement air filters (just standard 1") since Sam's had some nice Filtrete 1200D 4-packs with an $8 discount... Was comparing price against the usual Filtrete 1085 ones I get at Lowe's...

Of course I started going down the rabbit hole comparing other brands, then reading discussions about air flow restriction, etc, etc... Came across a post mentioning these beauties made by Honewell.

Honeywell (and other brands) make a 3-4" deep filter that will fit in a normal return air grill, assuming you have enough space behind the filter (which I have tons, I measured everything to make sure)....

Looking around I found Accumulair branded models for ~$30 each. Supposedly those are made in the USA.

Anyone have anything positive / negative to say about that style or brand?

Figure if there is no downside I will pull the trigger and get me a pair for my return air grates before I start using the A/C in the summer...

What is the Merv rating? I know that some HVAC system get affected by anything greater than an 8.

 

[strutaeng]

I've got an Aprilaire setup that I hate. The filters are only sold online and are not inexpensive. They are not standard size.

They are supposed to last 1 year, but every couple of months that I check it the media is clogged with dirt. No cats or dogs inside our house. Their website says that the filter becomes more efficient the longer the furnace runs. This to me is absurd! My return is on the floor, so I image it picks up more dust than in the ceiling.

I'm currently using basic pleated disposable filters that I change every month or so from the big box store and I seem to have much better airflow.

I would like to convert to standard 20x25x4 filters.

 

[EOC_Jason]

What is the Merv rating? I know that some HVAC system get affected by anything greater than an 8.

Merv ratings I've found you can get 8, 11, and 13 IIRC... You have to realize though with the greatly increased surface area you are reducing the amount of static pressure vs a 1"....

Here is a PDF, on the 2nd page they have a schematic of your return air, note how they want 7" of total clearance from the grill. Not an issue for me, my returns are in the ceiling and are at least 20"+ before transitioning to flex-duct.

https://customer.honeywell.com/resources/Techlit/TechLitDocuments/68-0000s/68-3062.pdf

Also one thing I've noted is that they state the max CFM for those filters, but I can't find d*ck on the Filtrete website... I hate companies that make things where you need specs like that but don't post it anywhere or you have to contact and they take a month to get back to you...

 

[larry4406]

No, it can be major modification to the HVAC system. When retrofitting, the 1" filter grille will be left in place w/o any filter, then there will be another filter housing to be installed somewhere near the furnace blower (air handler).

Arrow on filter should be pointed in direction of air flow (toward unit)...

 

[Crossfire05]

Merv ratings I've found you can get 8, 11, and 13 IIRC... You have to realize though with the greatly increased surface area you are reducing the amount of static pressure vs a 1"....

Here is a PDF, on the 2nd page they have a schematic of your return air, note how they want 7" of total clearance from the grill. Not an issue for me, my returns are in the ceiling and are at least 20"+ before transitioning to flex-duct.

https://customer.honeywell.com/resources/Techlit/TechLitDocuments/68-0000s/68-3062.pdf

Also one thing I've noted is that they state the max CFM for those filters, but I can't find d*ck on the Filtrete website... I hate companies that make things where you need specs like that but don't post it anywhere or you have to contact and they take a month to get back to you...

By surface area are you referring to the square footage of the filter itself (mine 16 x 16) or the medium through which the air travels. I would think that if you put in one of the beveled 4 inch units(in your pic) and left the square footage the same it would greatly restrict air flow.

 

[Showkey]

Surprised no has mentioned electronic or electro static filters. The last three home I have owned had them. Wash the prefilter and filter charged element .........when it starts making static discharge noises. Extremely low back pressure.

 

[larry4406]

Surprised no has mentioned electronic or electro static filters. The last three home I have owned had them. Wash the prefilter and filter charged element .........when it starts making static discharge noises. Extremely low back pressure.

I had an April Aire (?) electronic air cleaner with prefilter on my prior home. That was the only treatment. It was not sufficient. I installed filter return grilles as well and ran both. I think the added filters did the work.

 

[EOC_Jason]

By surface area are you referring to the square footage of the filter itself (mine 16 x 16) or the medium through which the air travels. I would think that if you put in one of the beveled 4 inch units(in your pic) and left the square footage the same it would greatly restrict air flow.

The amount of filter area is greatly increased because of the depth. Look how deep the pleats go!

Surprised no has mentioned electronic or electro static filters. The last three home I have owned had them. Wash the prefilter and filter charged element .........when it starts making static discharge noises. Extremely low back pressure.

Yeah, our old house had one. They were great and really do catch a lot more dust than any filter system IMO. But right now I'm not going to re-do my home system right now with one of those. Ours originally was where your filter grill would go but I've also seen some that mount up in the attic near the furnace....

 

[Done That]

Interesting! I looked at my furnace which is in a closet on the second floor. Looks like a problem doing that. Only 3 inches between the return and the furnace wall. See picture. My wife and I both have allergies and Utah is a dusty place (desert). It would be great to have well filtered air. I suppose under this situation the return air ducts get pretty dirty.

Trion Air Bear right angle and its Goodman clone GRAM-2000 are made to help in these tight fit situations. Trion has a data sheet on their website showing how it fits.

 

[Done That]

Their website says that the filter becomes more efficient the longer the furnace runs. This to me is absurd!

Technically its true. As a filter loads up less and less of anything can pass through it, so the efficiency (amount of **** out versus in) does go up. A piece of plywood in there for example is a 100% efficient filter if there is no bypassing on the edges. System may not like it...

 

[Crossfire05]

Trion Air Bear right angle and its Goodman clone GRAM-2000 are made to help in these tight fit situations. Trion has a data sheet on their website showing how it fits.

Not seeing how adding it to the furnace would add to the filters ability. Its still a problem of going to a thicker filter would restrict air flow. The filter earlier in the thread (4 inches) could be retrofitted to a ceiling 1 inch frame. Having two of those in the ceilings of the house would seem to give more flow then one thick filter at the furnace. Confusing comparison here whether its better for the furnace to have one filter close or two filters far.

 

[Crossfire05]

Not seeing how adding it to the furnace would add to the filters ability. Its still a problem of going to a thicker filter would restrict air flow. The filter earlier in the thread (4 inches) could be retrofitted to a ceiling 1 inch frame. Having two of those in the ceilings of the house would seem to give more flow then one thick filter at the furnace. Confusing comparison here whether its better for the furnace to have one filter close or two filters far.

To complicate things my furnace specifications call for a 28 3/8" x 21 1/2" x 3" filter. I have two 16 x 16 x 1 in my ceilings. Wish I knew more about HVAC.

 

[Done That]

To complicate things my furnace specifications call for a 28 3/8" x 21 1/2" x 3" filter. I have two 16 x 16 x 1 in my ceilings. Wish I knew more about HVAC.

Since you have allergies and expressed interest in better filtration you might want to locate a contractor who knows IAQ well and let them educate you and show you some options. Consultations are usually free.

Don't get hung up on where the filters are placed, and how many there are. As others have tried to explain, its all about deep pleats/surface area, plus the Merv rating of the material itself. Then a tech can review your circulator type and cfm settings to make sure the system is moving enough air.

 

[DC73]

I've got an Aprilaire setup that I hate.

There was an Aprilaire Spaceguard filter system installed at my last house. It was 28 years old when I sold the house. It worked very very well and I did only change the filter once per year. When I had the furnace/air handler/AC coil replaced after 26 years of age, the Tech commented that the system had the cleanest interior he had ever seen for one that needed replacing. He also thought the filter might have had something to do with the longevity of the equipment. That house was nearly dust free and required very little effort to manage what dust did accumulate.

Not so at my current house. I use a 2" MERV 12 filter here and the dust I have to manage is a major pain. I'll be looking into another Aprilaire system or equivalent when I get a chance.

DC

 

[rharman]

Surprised no has mentioned electronic or electro static filters. The last three home I have owned had them. Wash the prefilter and filter charged element .........when it starts making static discharge noises. Extremely low back pressure.

We spec'd the Honeywell electric cleaners when we remodeled our house. Eventually, the filter elements conked out. Got a rebuild kit which I recall was just the contacts. Didn't last too long. Switched to the 4" pleated filters that are a direct replacement and never looked back. Good prices on Amazon.

 

[gungatim]

LGR!

 

[Trey T]

I tried the pleated high micron filters once and didn't like the restrictions they caused and having to replace them more often (not to mention the cost).

I just use the std. 1" 16x25x1 from the box store and change them monthly.

The furnace is for heat/AC. I have separate Atmosphere air filtration systems I now use for air quality.

That's a new thing in the residential and light commercial HVAC world. Essentially, you'll have two intakes like a car (outside and recirculate modes) and controlled by a single motorized damper.

 

[Showkey]

I have a heat/cool recovery system or as some call an air exchange unit.........but.........it no way replaces the filter on the HVAC unit.

 

[gungatim]

That's a new thing in the residential and light commercial HVAC world. Essentially, you'll have two intakes like a car (outside and recirculate modes) and controlled by a single motorized damper.

To clarify, Atmosphere is the brand name of the separate stand alone units. it is not part of the HVAC system. They have built in particle sensors, separate carbon filter, electrostatic filter, and Hepa filter. not cheap but are allergy and asthma foundation certified and made my asthmatic kid able to sleep at night without a nebulizer...