Home Air Filtration: HVAC Filters for Healthy Air AND Ideal Airflow

Saw a 'big' 5" thick filter installed on a client's home, but you might be surprised to know it won't work on their system. Here's how to evaluate what specific filtration system to put on your home's HVAC. That Aprilaire 2516 I show in the video is only $250 and comes with MERV 16 included, fyi. Do your research and make sure your healthy air doesn't hurt your HVAC's air handler.

Here's the current pressure drop chart from Aprilaire's All Product Catalog:

Get 1-on-1 help with any help from Corbett:

[MrZammaraska]

This is one of the most underestimated component in HVAC design. Upgrading is a no brainer thank you!

[BDavidHome]

Wished the photo of your filter box was better to understand what's really going on here (or a schematic). It seems that there is a short transition from the huge filter box to the air handler that would create a bunch of air turbulence post filter. Anyway, I am happy to see your work to learn more in the HVAC discipline. In my area of Wisconsin the local HVAC companies don't really care much about the science and just keep doing installs like it was 1970. I act as a consultant to owners for house issues and do some of the actual work within my capabilities, or oversee work when I hire an "expert", something I love to do even as a guy in his 60's. Keep up the good work and thank you!

[mattyb]

Watching you and your wife for the last 3 years I was armed with the knowledge to install my 2 ton heat pump. I used the Aprilair 313 filterbox and it has worked great. Thank you!

[davidhoover]

Thanks for the info on Aprilaire! On 2 jobs recently I helped the clients swap out filters. They were using electronic filters, but never cleaning them because the installer didn’t say anything to them about it. They had zero filtration basically. On one of them, I was able to do a MERV 13 and the other a MERV 16 so they have some nice filtration. Crazy the stuff I see out there. Then they wonder why their drain line is always slimed up every few weeks.

[slipnfall]

Yes found out my 4T had an undersized 4" Aprilaire cabinet, not even spec'd for 1600cfm. It took several calls to contractors to find one who understood *why* I was bothering to have return ductwork upsized + cabinet changed out.

[DaveDugdaleColorado]

Funny, I use the filter you are talking about from Lennox, the X6675 MERV 16 with my 5 ton system (2000CFM). Luckily it has been working fine for me for the past 12 years. I am getting a good nanometer to measure the static pressure, I can only guess that it is very high when running at 2000CFM. When I go to replace my furnace to a heat pump I will make sure I get a filter system that can handle it.

[DavGreg]

We put in a heat pump (2022) to replace a spec system at the house which is doing great and saving money despite higher per kWH rates and I made sure that we had proper humidity control, fresh air (ERV) and HEPA filtration. Your content helped inform what I asked for and then asked about when looking at various system options from the local HVAC professionals. We live in a climate not too different from Atlanta and the system has performed flawlessly through everything from 110 plus (with very high humidity) down to -1 ℉.
The filter box is April Aire and is doing a great job.

[CH-pppy]

Corbett, do you have any opinions or existing videos on using wall or joist cavities as a return duct? Looks like it is not ideal but common practice. I am trying to understand how bad it really is though and if I should allow that in my home. Thanks!

[coldfingersub]

This is why I have always used 2 to 3 of those Lennox air filters 16. In custom sheet metal boxes..

My father showed me and demonstrated using an old Dwyer Magnehelic back in the late 1970s.

Currently replacing a customers 20” x 24” x 1” Merv 11 filter for a 5 ton air handler
with three 20”X25”X5” MERV 16 with a
Dwyer Magnehelic permanently installed across the filter for the customer with a permanent ink marker line to tell the customer when it’s time to change the filter.

[NurseAcrobat]

I was happy to finally modify my 3 ton heat pump's two 16 by 20 inch return filter grills to accept 4 inch thick filters in lieu of the standard 1 inch filters. I already had standalone HEPA filters, dehumidifiers, and an independently ducted ERV but being able to run the air handler continuously with large MERV 13 filters has still made a nice difference with my air quality monitoring and the general feel of the air.

[danslickers]

Excellent video
Grace and Peace
Slick

[popnozt]

I currently have a 20" x 25" filter slot and 1800 cfm. I would love to move up to the 31” x 28” but not sure how to do the custom transitions. Also the space is pretty tight. I could get a larger return air. Do you have a resources on transition details between the Aprilaire box and the air handler? A local HVAC company is trying to sell us on a Lennox PureAir Air Purification System but from your video I dont even thing our system can handle that.

[mustange]

Curious what you recommend for attic air handler designs for homes which weren't designed to have the attic to be considered conditioned space. Likely getting a new AC and i have two ceiling returns 20x40 (split with 20x20) and another 20x20. I just started used the retro fit filters for vents that usually would only fit 1". If I am changing my system should i look into having this Aprilaire 2516 installed?

[DaríoMartínez-ww]

Humble HVAC tech over here, it's funny I was just talking with my manager about this filter.

I believe that Healthy Climate has an 25x25x5 filter, I think that's the biggest they got, it would be interesting to see the pressure drop across it.

One question. I have a customer that suffers from a lot of allergies, they got someone to test their house for mold and found mold spores in the ductwork. I inspected the ductwork (it's In the attic) and it's probably the cleanest air handler and ductwork I've seen😊.

I'm thinking of recommending installing a filter like this. What are your thoughts on that?

[bubaks]

How often do these filters need to be cleaned or replaced?

[tcan]

Can you please explain how your configuration works. Is the filter in the cabinet at a 45 degree angle?

[AC-SuperCool]

"Great video as always, Corbett! Keep up the excellent work. I do have a point of contention, though. I believe you should be frustrated with any AC contractor who pulls this kind of stunt. They're definitely not doing it for free, and they're likely boasting about being the best. If I'm paying good money to a 'professional, ' they'd better do their job. No excuses."

[DrWarBear]

Hi Corbett, thank you for sharing this! I’d be curious to do a mock up of both systems and see what the particle count is on the air coming out the other end. My thought is, since the filter is larger than the duct feeding it air, wouldn’t that mean that you’re basically only using part of the filter? So would that affect the filter’s ability to actually pull particles and contaminants out of the air?

Curious your thoughts on that and if you’ve tested (I know you love your testing haha)

[naturalhealing]

Corbett, it would be great if you could do a video on the IQ Air and Intellipure whole house filter systems, what they would need for air flow and if they are worth it. Also, I would love to see a home made ERV / HRV system, if you have ever done that by building a box with filters.

[nathanbarry]

Trutech now has a filter box with even lower pressure drop, at the cost of being enormous and expensive. It’s much more expensive than the AprilAire, but they claim annual filter changes so the TCO is roughly a wash on a 10 year time scale. I’m excited that there is now more than 1 option.