# "Permanent" HVAC filters... any good?
**URL:** https://boards.straightdope.com/t/permanent-hvac-filters-any-good/536919
**Category:** Miscellaneous and Personal Stuff I Must Share
**Created:** [April 21, 2010, 9:11pm UTC](https://boards.straightdope.com/t/permanent-hvac-filters-any-good/536919 "2010-04-21T21:11:54Z")
**Posts on this page:** 9
**Page:** 1
### Author:  [@HMS\_Irruncible](https://boards.straightdope.com/u/HMS_Irruncible)
#### Post date: [April 21, 2010, 9:11pm UTC](https://boards.straightdope.com/t/permanent-hvac-filters-any-good/536919/1 "2010-04-21T21:11:54Z")
I’m an allergy sufferer, so when I discovered that my HVAC unit had a filter that needed to be washed instead of discarded, I was a little shocked and skeptical. The holes in that thing are visible to the naked eye, for crying out loud.
Can these so-called “permanent filters” that are hosed off instead of replaced really perform as well as disposable textile filters?
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### Author:  [@beowulff](https://boards.straightdope.com/u/beowulff)
#### Post date: [April 22, 2010, 1:29am UTC](https://boards.straightdope.com/t/permanent-hvac-filters-any-good/536919/2 "2010-04-22T01:29:18Z")
I have one, and I don’t think they work anywhere near as good as a conventional fiber filter. In fact, I’ve been thinking about creating my own design. As a datapoint, would you be willing to spend say, $150 on a washable filter that was guaranteed to filter air to HEPA standards (\>99.99% filtration at \>1 micron) and would last essentially forever (meaning the filter would last forever - you would need to wash it periodically)?
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### Author:  [@Unintentionally\_Blank](https://boards.straightdope.com/u/Unintentionally_Blank)
#### Post date: [April 22, 2010, 1:59am UTC](https://boards.straightdope.com/t/permanent-hvac-filters-any-good/536919/3 "2010-04-22T01:59:02Z")
We paid extra for ‘better’ filters, only to have the added restriction cause the A/C to freeze up solid. Cost us a repairman trip out for figger that one out.
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### Author:  [@beowulff](https://boards.straightdope.com/u/beowulff)
#### Post date: [April 22, 2010, 2:00am UTC](https://boards.straightdope.com/t/permanent-hvac-filters-any-good/536919/4 "2010-04-22T02:00:10Z")
> [@Unintentionally\_Blank](#):
>
> We paid extra for ‘better’ filters, only to have the added restriction cause the A/C to freeze up solid. Cost us a repairman trip out for figger that one out.
Yes, the pressure drop is a big issue - one of the reasons I’m sure my design is going to be expensive.
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### Author:  [@raindog](https://boards.straightdope.com/u/raindog)
#### Post date: [April 22, 2010, 3:18am UTC](https://boards.straightdope.com/t/permanent-hvac-filters-any-good/536919/5 "2010-04-22T03:18:29Z")
Don’t.
They won’t work as well, and will potentially damage your system, or at the very least cause your system to run longer than it should (in both heating and cooling) and A) Raise your utility bill by some small amount every month, and B) Shorten the life of your HVAC system.
Go with a good quality pleated filter
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### Author:  [@HMS\_Irruncible](https://boards.straightdope.com/u/HMS_Irruncible)
#### Post date: [April 22, 2010, 11:30am UTC](https://boards.straightdope.com/t/permanent-hvac-filters-any-good/536919/6 "2010-04-22T11:30:18Z")
> [@Unintentionally\_Blank](#):
>
> We paid extra for ‘better’ filters, only to have the added restriction cause the A/C to freeze up solid. Cost us a repairman trip out for figger that one out.
For those of us following at home, does that mean you replaced permanent filters with fiber filters, or vice versa?
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### Author:  [@Unintentionally\_Blank](https://boards.straightdope.com/u/Unintentionally_Blank)
#### Post date: [April 22, 2010, 11:53am UTC](https://boards.straightdope.com/t/permanent-hvac-filters-any-good/536919/7 "2010-04-22T11:53:51Z")
I replaced the $.99 paper filters with a $8 ‘Dirt Devil High Filtration’ filter.
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### Author:  [@Harmonious\_Discord](https://boards.straightdope.com/u/Harmonious_Discord)
#### Post date: [April 22, 2010, 11:54am UTC](https://boards.straightdope.com/t/permanent-hvac-filters-any-good/536919/8 "2010-04-22T11:54:02Z")
Those filters are a cheap way for the mfg. to prevent the grill slots from plugging in a week. They are not an allergen filter.
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### Author:  [@HMS\_Irruncible](https://boards.straightdope.com/u/HMS_Irruncible)
#### Post date: [April 22, 2010, 12:07pm UTC](https://boards.straightdope.com/t/permanent-hvac-filters-any-good/536919/9 "2010-04-22T12:07:00Z")
> [@Unintentionally\_Blank](#):
>
> I replaced the $.99 paper filters with a $8 ‘Dirt Devil High Filtration’ filter.
Okay, so you replaced a paper filter with a better paper filter? A vacuum cleaner filter? I’m just trying to understand because I’m asking about the permanent non-paper ones, and it’s not clear to me which type of filter a number of these responses are praising/carping about.
[QUOTE=HarmoniousDiscord]
Those filters are a cheap way for the mfg. to prevent the grill slots from plugging in a week. They are not an allergen filter.
[/quote]
Again, WHICH filters? Paper? Textile? Permanent?