<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">Thanks again, guys. I had a feeling that there would be at least one expert on the list, but it looks like I got two, at least in the first couple of hours. And, they both agree! :)<div class=""><br class=""></div><div class="">Jack: a differential meter is an interesting idea, especially given the cost of the bigger filters. It certainly doesn’t make sense to replace them more frequently than necessary. I am not a mechanical enginerd, just a plain old ordinary nerd. Still, I like playing around with new things. Would something like this work? <a href="https://www.amazon.com/Manometer-Differential-Backlight-Ventilation-Measurement/dp/B07K7HT3XJ/ref=asc_df_B07K7HT3XJ/?tag=hyprod-20&linkCode=df0&hvadid=312099766989&hvpos=&hvnetw=g&hvrand=20692614293351478&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9004590&hvtargid=pla-622729475514&psc=1" class="">https://www.amazon.com/Manometer-Differential-Backlight-Ventilation-Measurement/dp/B07K7HT3XJ/ref=asc_df_B07K7HT3XJ/?tag=hyprod-20&linkCode=df0&hvadid=312099766989&hvpos=&hvnetw=g&hvrand=20692614293351478&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9004590&hvtargid=pla-622729475514&psc=1</a>. I’m thinking of drilling a couple of holes in the filter box and semi-permanently mounting it. </div><div class=""><br class=""></div><div class="">Jim<br class=""><div><br class=""><blockquote type="cite" class=""><div class="">On Dec 13, 2021, at 7:21 PM, Jack Brooks <<a href="mailto:JIBrooks@live.com" class="">JIBrooks@live.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><meta charset="UTF-8" class=""><div class="WordSection1" style="page: WordSection1; caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 14px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;"><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 12pt; font-family: "Times New Roman", serif; color: rgb(0, 32, 96);" class="">Bingo! Jim hit the nail on the head. <o:p class=""></o:p></span></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 12pt; font-family: "Times New Roman", serif; color: rgb(0, 32, 96);" class=""><o:p class=""> </o:p></span></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 12pt; font-family: "Times New Roman", serif; color: rgb(0, 32, 96);" class="">The 4 inch filter has a lower pressure drop because of overall greater filtration area due to all of the deep pleats. It also has a lower frequency of filter change out for the same reason. Using two one inch filters together will impact your flow. It may not affect your performance noticeably, but it will change the system flow, drive up fan energy costs, etc. <span class="Apple-converted-space"> </span><br class=""><br class=""><a href="https://nordicpure.com/" style="color: blue; text-decoration: underline;" class="">https://nordicpure.com/</a><span class="Apple-converted-space"> </span>seems to have a lot of sizes in stock and they are not too badly priced either on their website or Amazon. I’ve used them for a while and am happy with them. They are available in a wide range of MERV ratings too.<o:p class=""></o:p></span></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 12pt; font-family: "Times New Roman", serif; color: rgb(0, 32, 96);" class=""><o:p class=""> </o:p></span></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 12pt; font-family: "Times New Roman", serif; color: rgb(0, 32, 96);" class="">I have a differential pressure meter across my filter. It registers 0-0.25 inches of H<sub class="">2</sub>O. I let that guide my changeout frequency, which often is around a year before the pressure drop indicate to me that it should be changed. Ok, yes, I am a Mechanical Enginerd.<o:p class=""></o:p></span></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 12pt; font-family: "Times New Roman", serif; color: rgb(0, 32, 96);" class=""><br class="">Jack<o:p class=""></o:p></span></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 12pt; font-family: "Times New Roman", serif; color: rgb(0, 32, 96);" class=""><o:p class=""> </o:p></span></div><div style="border-style: solid none none; border-top-width: 1pt; border-top-color: rgb(225, 225, 225); padding: 3pt 0in 0in;" class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><b class="">From:</b><span class="Apple-converted-space"> </span>Shop-talk <<a href="mailto:shop-talk-bounces@autox.team.net" class="">shop-talk-bounces@autox.team.net</a>><span class="Apple-converted-space"> </span><b class="">On Behalf Of<span class="Apple-converted-space"> </span></b>John Innis<br class=""><b class="">Sent:</b><span class="Apple-converted-space"> </span>Monday, December 13, 2021 2:44 PM<br class=""><b class="">To:</b><span class="Apple-converted-space"> </span>Jim Stone <<a href="mailto:1789alpine@gmail.com" class="">1789alpine@gmail.com</a>><br class=""><b class="">Cc:</b><span class="Apple-converted-space"> </span>Shop Talk <<a href="mailto:shop-talk@autox.team.net" class="">shop-talk@autox.team.net</a>><br class=""><b class="">Subject:</b><span class="Apple-converted-space"> </span>Re: [Shop-talk] Furnace Filters<o:p class=""></o:p></div></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">The only real issue is that you will not get as much airflow through a 1" filter of a given effectiveness. Most of the time that's not a big deal. In our previous house we did have an issue with the AC freezing up when it was working really hard. In that case the solution was a lower effectiveness filter because the box could not accommodate a thicker filter. If you are happy with the performance of the 1" filter and have not had any issues, i'd say stick with it. I do NOT recommend stacking two one inch filters. <o:p class=""></o:p></div></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div class=""><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">On Mon, Dec 13, 2021 at 4:20 PM Jim Stone <<a href="mailto:1789alpine@gmail.com" style="color: blue; text-decoration: underline;" class="">1789alpine@gmail.com</a>> wrote:<o:p class=""></o:p></div></div><blockquote style="border-style: none none none solid; border-left-width: 1pt; border-left-color: rgb(204, 204, 204); padding: 0in 0in 0in 6pt; margin: 5pt 0in 5pt 4.8pt;" class=""><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">The company that installed my HVAC system a few years ago used a filter box on the return line that takes 20” x 25" x<b class=""><span class="Apple-converted-space"> </span>4”</b><span class="Apple-converted-space"> </span>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” x 25" x<span class="Apple-converted-space"> </span><b class="">1”<span class="Apple-converted-space"> </span></b>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’t just use 1” 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’t think there is any danger of them tipping, but two would make it impossible.<o:p class=""></o:p></div><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div></div><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">Thanks,<o:p class=""></o:p></div></div><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">Jim<o:p class=""></o:p></div></div></div><p class="MsoNormal" style="margin: 0in 0in 12pt; font-size: 11pt; font-family: Calibri, sans-serif;">_______________________________________________<br class=""><br class=""><a href="mailto:Shop-talk@autox.team.net" target="_blank" style="color: blue; text-decoration: underline;" class="">Shop-talk@autox.team.net</a><br class="">Donate:<span class="Apple-converted-space"> </span><a href="http://www.team.net/donate.html" target="_blank" style="color: blue; text-decoration: underline;" class="">http://www.team.net/donate.html</a><br class="">Suggested annual donation $12.96<br class="">Archive:<span class="Apple-converted-space"> </span><a href="http://www.team.net/pipermail/shop-talk" target="_blank" style="color: blue; text-decoration: underline;" class="">http://www.team.net/pipermail/shop-talk</a><span class="Apple-converted-space"> </span><a href="http://autox.team.net/archive" target="_blank" style="color: blue; text-decoration: underline;" class="">http://autox.team.net/archive</a><br class=""><br class="">Unsubscribe/Manage:<span class="Apple-converted-space"> </span><a href="http://autox.team.net/mailman/options/shop-talk/jdinnis@gmail.com" target="_blank" style="color: blue; text-decoration: underline;" class="">http://autox.team.net/mailman/options/shop-talk/jdinnis@gmail.com</a><o:p class=""></o:p></p></blockquote></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><br clear="all" class=""><br class="">--<span class="Apple-converted-space"> </span><o:p class=""></o:p></div><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">=================================<br class="">= Never offend people with style when you =<br class="">= can offend with substance --- Sam Brown =<br class="">=================================</div></div></div></div></blockquote></div><br class=""></div></body></html>