Comments on: How to Make a Good High-MERV Filter Even Better https://www.energyvanguard.com/blog/how-to-make-good-high-merv-filter-better/ Building science knowledge, HVAC design, & fun Tue, 01 Feb 2022 15:15:13 +0000 hourly 1 https://wordpress.org/?v=6.6.2 By: Chris Heenan https://www.energyvanguard.com/blog/how-to-make-good-high-merv-filter-better/#comment-19441 Tue, 01 Feb 2022 15:15:13 +0000 http://energyvanguard.flywheelsites.com/?blog_post=how-to-make-a-good-high-merv-filter-even-better#comment-19441 Belaboring the obvious… the return box is an attic.

Is the return box insulated?

More than a 15 degree temp difference between the return air and the attic temp.

Probably wont sweat but surely needs to be insulated to r R-8.

]]> By: Allison Bailes https://www.energyvanguard.com/blog/how-to-make-good-high-merv-filter-better/#comment-15748 Tue, 06 Jul 2021 23:55:13 +0000 http://energyvanguard.flywheelsites.com/?blog_post=how-to-make-a-good-high-merv-filter-even-better#comment-15748 In reply to Alan Kiehle.

Alan, that’s great! Cutting your filter pressure drop in half and going to MERV-13 at the same time definitely qualifies as an all-cap SUCCESS! Thanks for coming here and posting what you did and the results you got.

]]> By: Alan Kiehle https://www.energyvanguard.com/blog/how-to-make-good-high-merv-filter-better/#comment-15747 Tue, 06 Jul 2021 21:51:33 +0000 http://energyvanguard.flywheelsites.com/?blog_post=how-to-make-a-good-high-merv-filter-even-better#comment-15747 In reply to Alan Kiehle.

I measured the pressure drops behind the wall filter grille in my closet and measured about .2 in wc when the Home Depot 1″ FPR 4 filter was in the grille. When I replaced 1″ grille with a 2″, the pressure drop was reduced to about .15 in wc! A measurement with another 2″ filter grille installed just above my original gave .1 in wc!
So, as you can see, the good quality 2″ filter passed air more easily than the 1″. Also, cutting another opening allowed many more molecules to enter the wall cavity (per unit time).
I guess it’s time to mention that my 2″ filters were MERV 13. SUCCESS!!!
Maybe I can go to MERV 15. Don’t know.
Thanks for your articles, Dr Bailes.

]]> By: Harry https://www.energyvanguard.com/blog/how-to-make-good-high-merv-filter-better/#comment-13589 Tue, 26 Jan 2021 07:30:29 +0000 http://energyvanguard.flywheelsites.com/?blog_post=how-to-make-a-good-high-merv-filter-even-better#comment-13589 Hi,
Can you provide more resources (articles, papers, analysis, etc.) about the free air space above a filter? I am curious why 6 inches in a minimum for a four inch filter.

BTW, I have the EXACT set up your original system used and I am debating creating a rectangular return plenum (like yours – and remove the 90) or use a square to round transition with a 90. I am not sure which option would give the lowest pressure drop for the return portion of the system.
Thoughts?
Thanks!!

]]> By: Rick Hackbarth https://www.energyvanguard.com/blog/how-to-make-good-high-merv-filter-better/#comment-13586 Sat, 16 Jan 2021 22:41:17 +0000 http://energyvanguard.flywheelsites.com/?blog_post=how-to-make-a-good-high-merv-filter-even-better#comment-13586 In reply to abailes.

Speaking of going off tangent, give it time. Calli might have enjoyed another dog friend herself and it would not be disrespectful to her in any way for you to consider another one yourself. Since you called her the best dog ever I assume you like dogs? With my pets my longevity concern is that I outlive them since I don’t want them wondering “what the hell?” were I to suddenly not be there. Another dog will not make you feel like a traitor. Just sayin’.

]]> By: Dane W https://www.energyvanguard.com/blog/how-to-make-good-high-merv-filter-better/#comment-13588 Fri, 15 Jan 2021 20:38:35 +0000 http://energyvanguard.flywheelsites.com/?blog_post=how-to-make-a-good-high-merv-filter-even-better#comment-13588 What are your thoughts on the filter enclosure Risinger used on the HVAC at his house, seems like it would be a little on the small side?

https://www.youtube.com/watch?v=ud5oAmTHcM4&t=960s

]]> By: Alan Kiehle https://www.energyvanguard.com/blog/how-to-make-good-high-merv-filter-better/#comment-13587 Thu, 10 Dec 2020 17:56:43 +0000 http://energyvanguard.flywheelsites.com/?blog_post=how-to-make-a-good-high-merv-filter-even-better#comment-13587 Pinching the air is automatic with a wall air return. I have only one air return and it’s in the living room wall. I put in a second one above the first hoping to reduce the pressure drop.
Unfortunately, I do not have a tool to measure the air velocity but have noticed that the air speed is much higher in the upper filter using a piece of toilet paper. This makes sense but I didn’t think about this before I cut the second hole. (I would expect the air speed to decrease when measured from the highest to lowest points.) Because there is some air flow through the lower filter I don’t believe that I’ve wasted my time.
I am considering enlarging both of my return air grilles but don’t think this will reduce the pressure drop much.
Has anyone collected any data on wall returns? Any thoughts?
I am considering connecting a second air return duct to my attic plenum but – the work or expense! – my system is old.
Note: My wall cavity was constructed using 2″x6″s and is therefore 5.5″ deep.

]]> By: John W https://www.energyvanguard.com/blog/how-to-make-good-high-merv-filter-better/#comment-13529 Tue, 13 Oct 2020 21:27:24 +0000 http://energyvanguard.flywheelsites.com/?blog_post=how-to-make-a-good-high-merv-filter-even-better#comment-13529 Does a good filter (Merv 13+)
Does a good filter (Merv 13+) actually trap more particles as it gets dirtier? Assuming you would not leave it in service past it’s intended pressure drop.

]]> By: Ellen N Eggerton https://www.energyvanguard.com/blog/how-to-make-good-high-merv-filter-better/#comment-13526 Thu, 08 Oct 2020 21:07:51 +0000 http://energyvanguard.flywheelsites.com/?blog_post=how-to-make-a-good-high-merv-filter-even-better#comment-13526 I have two returns that
I have two returns that connect just before the filter. Should I consider reconfiguring my returns to have filters instead of the smaller combined filter just before the furnace fan intake? I would have to have the duct work done by others as I am not that handy nor do I have the tools.

]]> By: abailes https://www.energyvanguard.com/blog/how-to-make-good-high-merv-filter-better/#comment-13509 Thu, 24 Sep 2020 19:11:21 +0000 http://energyvanguard.flywheelsites.com/?blog_post=how-to-make-a-good-high-merv-filter-even-better#comment-13509 In reply to Charlie Conger.

Charlie, it sounds like you

Charlie, it sounds like you have a great system.  Regarding turning vanes in my return boxes, I don’t think they’d help much because the velocity is so low.  The face velocity for the filter is a bit over 100 ft/min.  The velocity in the 14″ duct is less than 300 ft/min.  There’s probably not a lot turbulence to smooth out at those velocities.

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