Subject: [Shop-talk] Furnace Filters

From: Jim Stone <[email-masked]>
Date: Mon, 13 Dec 2021 17:19:49 -0500

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The company that installed my HVAC system a few years ago used a filter =
box on the return line that takes 20=E2=80=9D x 25" x 4=E2=80=9D =
filters, which is an unusual, and thus expensive, size - filters =
generally run about $25 each - that is not readily available other than =
online.  During construction, my general contractor just had a cheap =
20=E2=80=9D x 25" x 1=E2=80=9D filter in there that seemed to work just =
fine.  I checked the installation instructions for the furnace and there =
are no specifications for the filters, other than that they need to be =
changed regularly, which is getting pretty expensive.  Is there any =
reason I couldn=E2=80=99t just use 1=E2=80=9D filters, which are less =
than half the price?  Maybe even put two of them in the box, a good one =
first to catch most of the dust and a cheap one like the contractor used =
as a secondary one.  It is a snug fit and I don=E2=80=99t think there is =
any danger of them tipping, but two would make it impossible.

Thanks,
Jim=

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<html><head><meta http-equiv=3D"Content-Type" content=3D"text/html; =
charset=3Dutf-8"></head><body style=3D"word-wrap: break-word; =
-webkit-nbsp-mode: space; line-break: after-white-space;" class=3D"">The =
company that installed my HVAC system a few years ago used a filter box =
on the return line that takes 20=E2=80=9D x 25" x<b class=3D""> 4=E2=80=9D=
</b> filters, which is an unusual, and thus expensive, size - filters =
generally run about $25 each - that is not readily available other than =
online. &nbsp;During construction, my general contractor just had =
a&nbsp;cheap 20=E2=80=9D x 25" x <b class=3D"">1=E2=80=9D </b>filter in =
there that seemed to work just fine. &nbsp;I checked the installation =
instructions for the furnace and there are no specifications for the =
filters, other than that they need to be changed regularly, which is =
getting pretty expensive. &nbsp;Is there any reason I couldn=E2=80=99t =
just use 1=E2=80=9D filters, which are less than half the price? =
&nbsp;Maybe even put two of them in the box, a good one first to catch =
most of the dust and a cheap one like the contractor used as a secondary =
one. &nbsp;It is a snug fit and I don=E2=80=99t think there is any =
danger of them tipping, but two would make it impossible.<div =
class=3D""><br class=3D""></div><div class=3D"">Thanks,</div><div =
class=3D"">Jim</div></body></html>=

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_______________________________________________

[email-masked]
Archive: http://www.team.net/pipermail/shop-talk http://autox.team.net/archive

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From: Jim Stone <[email-masked]>
Date: Tue, 14 Dec 2021 11:30:06 -0500

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Thanks, guys!  For now I will stay with the 4=E2=80=9D filters and add the g=
auge to my list of fun things to do when I have a little extra time.=20

Sent from my iPhone

> On Dec 14, 2021, at 6:37 AM, Tom Coradeschi <[email-masked]> wrote:
>=20
> =EF=BB=BFNow you=E2=80=99re getting to the point. Filtration efficiency is=
 going to be measured in MERV (and/or MPR, if you=E2=80=99re 3M) and should b=
e independent of filter thickness.=20
>=20
> What the 4=E2=80=9D filter buys you is (for the same filtration efficiency=
) longer filter life, and, maybe, lower pressure drop across the filter. The=
 $64k question is: how much lower, and does it really make a difference? If y=
ou do end up buying a differential pressure gage, would you be interested in=
 running 1=E2=80=9D vs 4=E2=80=9D and reporting out what you see? You=E2=80=99=
d have to conjure up a way to seal up the duct so you get a good upstream re=
ading with the 1=E2=80=9D, I think.=20
>=20
> Another ME here, albeit one who is not crazy about doing sheet metal work =E2=
=80=A6 at least not crazy enough that I see the point in going to a 4=E2=80=9D=
 filter, sans data showing it to be worth the effort. And I have a box full o=
f 1=E2=80=9D MERV 13 filters to use up - on a 3 month change cycle I am good=
 until early 2023, at this point:-)
>=20
> Whatever you do, don=E2=80=99t stack 1=E2=80=9D filters. They will act lik=
e two resistors in series - your blower motor will almost certainly not resp=
ond well to that.=20
>=20
> Regards,
>=20
> Tom Coradeschi
> [email-masked]
>=20
>>> On Dec 13, 2021, at 7:03 PM, Jim Stone <[email-masked]> wrote:
>>>=20
>> =EF=BB=BFThanks, guys.  That is all good feedback. David: I hadn=E2=80=99=
t considered using a washable filter, but it is an interesting idea.  It loo=
ks like a 4=E2=80=9D one will cost me around $100, so the breakeven point is=
 after a year.  Not too bad.
>>=20
>> But, here is an interesting point that showed up tangentially when I Goog=
led =E2=80=9Cwashable furnace filters=E2=80=9D:=20
>>=20
>> Fortunately, most 20x25x4 air filters last between six to eight months. B=
y that calculation, the average homeowners will not need more than two 20x25=
x4 air filters in any given year. In contrast, a one-inch air filter will ne=
ed to be changed every two to three months.  https://servicechampions.com/be=
nefits-of-a-20x25x4-air-filter-installed-in-your-furnace/
>>=20
>> If that is true, the cost difference between the 4=E2=80=9D and 1=E2=80=9D=
 disappears.  Thoughts?
>>=20
>> Jim=20
>>=20
>>=20
>>> On Dec 13, 2021, at 5:32 PM, Pat Horne <[email-masked]> wrote:
>>>=20
>>> My shop air handler is set up to use a 2=E2=80=9D filter but the install=
er said to use 2 one inch filters, both good ones. I watch the first one & r=
emove it when it is too dirty, move the second one up & install a new second=
 one.=20
>>> There is some discoloration on the second filter, so it is doing somethi=
ng.=20
>>>=20
>>> If you want to go with two different ones, I=E2=80=99d put the poorer on=
e first, followed by the better one.=20
>>>=20
>>> My HVAC guy says to not use the corrugated filters, nor the fiberglass o=
nes that you can see throughout. He sells me Purolator 312 filters by the ca=
se.=20
>>>=20
>>> Peace,
>>> Pat
>>>=20
>>> Pat Horne=20
>>> We support Habitat for Humanity
>>>=20
>>>=20
>>> On Dec 13, 2021, at 4:21 PM, Jim Stone <[email-masked]> wrote:
>>>=20
>>> =EF=BB=BFThe company that installed my HVAC system a few years ago used a=
 filter box on the return line that takes 20=E2=80=9D x 25" x 4=E2=80=9D fil=
ters, which is an unusual, and thus expensive, size - filters generally run a=
bout $25 each - that is not readily available other than online.  During con=
struction, my general contractor just had a cheap 20=E2=80=9D x 25" x 1=E2=80=
=9D filter in there that seemed to work just fine.  I checked the installati=
on instructions for the furnace and there are no specifications for the filt=
ers, other than that they need to be changed regularly, which is getting pre=
tty expensive.  Is there any reason I couldn=E2=80=99t just use 1=E2=80=9D f=
ilters, which are less than half the price?  Maybe even put two of them in t=
he box, a good one first to catch most of the dust and a cheap one like the c=
ontractor used as a secondary one.  It is a snug fit and I don=E2=80=99t thi=
nk there is any danger of them tipping, but two would make it impossible.
>>>=20
>>> Jim
>>>=20
>>> Donate: http://www.team.net/donate.html
>>> Suggested annual donation  $12.96
>>> Archive: http://www.team.net/pipermail/shop-talk http://autox.team.net/a=
rchive
>>>=20
>>> Unsubscribe/Manage: http://autox.team.net/mailman/options/shop-talk/pati=
[email-masked]
>>>=20
>>=20
>>=20
>> Donate: http://www.team.net/donate.html
>> Suggested annual donation  $12.96
>> Archive: http://www.team.net/pipermail/shop-talk http://autox.team.net/ar=
chive
>>=20
>> Unsubscribe/Manage: http://autox.team.net/mailman/options/shop-talk/tjcor=
[email-masked]
>>=20
>=20
> Donate: http://www.team.net/donate.html
> Suggested annual donation  $12.96
> Archive: http://www.team.net/pipermail/shop-talk http://autox.team.net/arc=
hive
>=20
> Unsubscribe/Manage: http://autox.team.net/mailman/options/shop-talk/1789al=
[email-masked]
>=20

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<html><head><meta http-equiv=3D"content-type" content=3D"text/html; charset=3D=
utf-8"></head><body dir=3D"auto">Thanks, guys! &nbsp;For now I will stay wit=
h the 4=E2=80=9D filters and add the gauge to my list of fun things to do wh=
en I have a little extra time.&nbsp;<br><br><div dir=3D"ltr">Sent from my iP=
hone</div><div dir=3D"ltr"><br><blockquote type=3D"cite">On Dec 14, 2021, at=
 6:37 AM, Tom Coradeschi &lt;[email-masked]&gt; wrote:<br><br></blockquot=
e></div><blockquote type=3D"cite"><div dir=3D"ltr">=EF=BB=BF<meta http-equiv=
=3D"content-type" content=3D"text/html; charset=3Dutf-8">Now you=E2=80=99re g=
etting to the point. Filtration efficiency is going to be measured in MERV (=
and/or MPR, if you=E2=80=99re 3M) and should be independent of filter thickn=
ess.&nbsp;<div><br></div><div>What the 4=E2=80=9D filter buys you is (for th=
e same filtration efficiency) longer filter life, and, maybe, lower pressure=
 drop across the filter. The $64k question is: how much lower, and does it r=
eally make a difference? If you do end up buying a differential pressure gag=
e, would you be interested in running 1=E2=80=9D vs 4=E2=80=9D and reporting=
 out what you see? You=E2=80=99d have to conjure up a way to seal up the duc=
t so you get a good upstream reading with the 1=E2=80=9D, I think.&nbsp;</di=
v><div><br></div><div>Another ME here, albeit one who is not crazy about doi=
ng sheet metal work =E2=80=A6 at least not crazy enough that I see the point=
 in going to a 4=E2=80=9D filter, sans data showing it to be worth the effor=
t. And I have a box full of 1=E2=80=9D MERV 13 filters to use up - on a 3 mo=
nth change cycle I am good until early 2023, at this point:-)</div><div><br>=
</div><div>Whatever you do, don=E2=80=99t stack 1=E2=80=9D filters. They wil=
l act like two resistors in series - your blower motor will almost certainly=
 not respond well to that.&nbsp;</div><div><br></div><div>Regards,</div><div=
><br><div dir=3D"ltr">Tom Coradeschi<div>[email-masked]</div></div><div d=
ir=3D"ltr"><br><blockquote type=3D"cite">On Dec 13, 2021, at 7:03 PM, Jim St=
one &lt;[email-masked]&gt; wrote:<br><br></blockquote></div><blockquot=
e type=3D"cite"><div dir=3D"ltr">=EF=BB=BF<meta http-equiv=3D"Content-Type" c=
ontent=3D"text/html; charset=3Dutf-8">Thanks, guys. &nbsp;That is all good f=
eedback. David: I hadn=E2=80=99t considered using a washable filter, but it i=
s an interesting idea. &nbsp;It looks like a 4=E2=80=9D one will cost me aro=
und $100, so the breakeven point is after a year. &nbsp;Not too bad.<div cla=
ss=3D""><br class=3D""></div><div class=3D"">But, here is an interesting poi=
nt that showed up tangentially when I Googled =E2=80=9Cwashable furnace filt=
ers=E2=80=9D:&nbsp;</div><div class=3D""><br class=3D""></div><blockquote st=
yle=3D"margin: 0 0 0 40px; border: none; padding: 0px;" class=3D""><div clas=
s=3D""><font color=3D"#0433ff" class=3D""><span style=3D"caret-color: rgb(32=
, 33, 36); font-family: &quot;Google Sans Text&quot;, arial, sans-serif; bac=
kground-color: rgb(255, 255, 255);" class=3D"">Fortunately, most 20x25x4 air=
 filters last between&nbsp;</span><b style=3D"caret-color: rgb(32, 33, 36); f=
ont-family: &quot;Google Sans Text&quot;, arial, sans-serif;" class=3D"">six=
 to eight months</b><span style=3D"caret-color: rgb(32, 33, 36); font-family=
: &quot;Google Sans Text&quot;, arial, sans-serif; background-color: rgb(255=
, 255, 255);" class=3D"">. By that calculation, the average homeowners will n=
ot need more than two 20x25x4 air filters in any given year. In contrast, a o=
ne-inch air filter will need to be changed every two to three months. &nbsp;=
</span></font><a href=3D"https://servicechampions.com/benefits-of-a-20x25x4-=
air-filter-installed-in-your-furnace/" class=3D"">https://servicechampions.c=
om/benefits-of-a-20x25x4-air-filter-installed-in-your-furnace/</a></div></bl=
ockquote><div class=3D""><div><br class=3D""></div><div>If that is true, the=
 cost difference between the 4=E2=80=9D and 1=E2=80=9D disappears. &nbsp;Tho=
ughts?</div><div><br class=3D""></div><div>Jim&nbsp;</div><div><br class=3D"=
"></div><div><br class=3D""><blockquote type=3D"cite" class=3D""><div class=3D=
"">On Dec 13, 2021, at 5:32 PM, Pat Horne &lt;<a href=3D"mailto:patintexas@i=
cloud.com" class=3D"">[email-masked]</a>&gt; wrote:</div><br class=3D=
"Apple-interchange-newline"><div class=3D""><meta http-equiv=3D"content-type=
" content=3D"text/html; charset=3Dutf-8" class=3D""><div dir=3D"auto" class=3D=
"">My shop air handler is set up to use a 2=E2=80=9D filter but the installe=
r said to use 2 one inch filters, both good ones. I watch the first one &amp=
; remove it when it is too dirty, move the second one up &amp; install a new=
 second one.&nbsp;<div class=3D"">There is some discoloration on the second f=
ilter, so it is doing something.&nbsp;</div><div class=3D""><br class=3D""><=
/div><div class=3D"">If you want to go with two different ones, I=E2=80=99d p=
ut the poorer one first, followed by the better one.&nbsp;</div><div class=3D=
""><br class=3D""></div><div class=3D"">My HVAC guy says to not use the corr=
ugated filters, nor the fiberglass ones that you can see throughout. He sell=
s me Purolator 312 filters by the case.&nbsp;<br class=3D""><br class=3D"">P=
eace,</div><div class=3D"">Pat</div><div class=3D""><br class=3D""><div dir=3D=
"ltr" class=3D"">Pat Horne&nbsp;<div class=3D"">We support Habitat for Human=
ity</div><div class=3D""><br class=3D""></div></div><div dir=3D"ltr" class=3D=
""><br class=3D"">On Dec 13, 2021, at 4:21 PM, Jim Stone &lt;<a href=3D"mail=
to:[email-masked]" class=3D"">[email-masked]</a>&gt; wrote:<br c=
lass=3D""><br class=3D""></div><div dir=3D"ltr" class=3D"">=EF=BB=BF<meta ht=
tp-equiv=3D"Content-Type" content=3D"text/html; charset=3Dutf-8" class=3D"">=
The company that installed my HVAC system a few years ago used a filter box o=
n the return line that takes 20=E2=80=9D x 25" x<b class=3D""> 4=E2=80=9D</b=
> filters, which is an unusual, and thus expensive, size - filters generally=
 run about $25 each - that is not readily available other than online. &nbsp=
;During construction, my general contractor just had a&nbsp;cheap 20=E2=80=9D=
 x 25" x <b class=3D"">1=E2=80=9D </b>filter in there that seemed to work ju=
st fine. &nbsp;I checked the installation instructions for the furnace and t=
here are no specifications for the filters, other than that they need to be c=
hanged regularly, which is getting pretty expensive. &nbsp;Is there any reas=
on I couldn=E2=80=99t just use 1=E2=80=9D filters, which are less than half t=
he price? &nbsp;Maybe even put two of them in the box, a good one first to c=
atch most of the dust and a cheap one like the contractor used as a secondar=
y one. &nbsp;It is a snug fit and I don=E2=80=99t think there is any danger o=
f them tipping, but two would make it impossible.<div class=3D""><br class=3D=
""></div><div class=3D"">Thanks,</div><div class=3D"">Jim</div><span class=3D=
"">_______________________________________________</span><br class=3D""><spa=
n class=3D""></span><br class=3D""><span class=3D""><a href=3D"mailto:Shop-t=
[email-masked]" class=3D"">[email-masked]</a></span><br class=3D=
""><span class=3D"">Donate: <a href=3D"http://www.team.net/donate.html" clas=
s=3D"">http://www.team.net/donate.html</a></span><br class=3D""><span class=3D=
"">Suggested annual donation &nbsp;$12.96</span><br class=3D""><span class=3D=
"">Archive: <a href=3D"http://www.team.net/pipermail/shop-talk" class=3D"">h=
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cloud.com</a></span><br class=3D""><span class=3D""></span><br class=3D""></=
div></div></div></div></blockquote></div><br class=3D""></div><span>________=
_______________________________________</span><br><span></span><br><span>Sho=
[email-masked]</span><br><span>Donate: http://www.team.net/donate.htm=
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an><br><span></span><br><span>[email-masked]</span><br><span>Donat=
e: http://www.team.net/donate.html</span><br><span>Suggested annual donation=
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[email-masked]

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