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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal>Drake,<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>The best thing to minimize blower power draw will be two fold.<o:p></o:p></p><ol style='margin-top:0in' start=1 type=1><li class=MsoListParagraph style='margin-left:0in;mso-list:l0 level1 lfo1'>Get the smallest BTU furnace you are allowed to (with and ECM blower). Since blowers are generally sized at a nominal CFM/BTU of heat output. (Around 30CFM/ 1000BTU for the usual heat pump or 90+eff furnaces)<o:p></o:p></li><li class=MsoListParagraph style='margin-left:0in;mso-list:l0 level1 lfo1'>Minimize head loss in the duct system. Head loss has an exponential effect on energy use as a whole (blower motor and fuel efficiency) <o:p></o:p></li><ol style='margin-top:0in' start=1 type=a><li class=MsoListParagraph style='margin-left:0in;mso-list:l0 level2 lfo1'>Bigger distribution ducts <o:p></o:p></li><li class=MsoListParagraph style='margin-left:0in;mso-list:l0 level2 lfo1'>metal duct for corners and turns (i.e use good fittings)<o:p></o:p></li><li class=MsoListParagraph style='margin-left:0in;mso-list:l0 level2 lfo1'>little to no flex duct unless for straight runs<o:p></o:p></li></ol></ol><p class=MsoListParagraph style='margin-left:1.5in;text-indent:-1.5in;mso-text-indent-alt:-9.0pt;mso-list:l0 level3 lfo1'><![if !supportLists]><span style='mso-list:Ignore'><span style='font:7.0pt "Times New Roman"'> </span>i.<span style='font:7.0pt "Times New Roman"'> </span></span><![endif]>flex duct always well supported and pulled tight, little to no slack allowed in a flex duct job.<o:p></o:p></p><ol style='margin-top:0in' start=2 type=1><ol style='margin-top:0in' start=4 type=a><li class=MsoListParagraph style='margin-left:0in;mso-list:l0 level2 lfo1'>Etc… Good read in this article, and the attached presentation download: <a href="https://www.energyvanguard.com/blog/secret-moving-air-quietly-through-your-duct-system">https://www.energyvanguard.com/blog/secret-moving-air-quietly-through-your-duct-system</a> <o:p></o:p></li></ol></ol><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Not knowing the home layout and specs it hard to give specific advise on that side, but those two items are big drivers on actual power needs for blowers. But as you said, the furnace is there for insurance costs, not primary heating…<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Also, the unvented propane heater in a primary dwelling seems like a bad idea to me. Is the home expected to be well sealed for air leaks? Blower door tested, relatively well sealed would be a blower door number of less than 2-3 ACH50 (air changes per hour @ a 50pascal pressure difference to the outdoors), 1-1.5 is really good, and passive house is 0.6 and lower? Because both the fireplace and the unvented heater could be bad news if that’s the case… Something you might want to see if you client is conscious of. (Not sure how far you are getting involved in the home design Drake.)<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal>With Regards,<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Daniel Young, <o:p></o:p></p><p class=MsoNormal>NABCEP Certified PV Installation Professional<sup>TM</sup>: Cert #031508-90<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p></div><p class=MsoNormal><o:p> </o:p></p><div><div style='border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b>From:</b> RE-wrenches <re-wrenches-bounces@lists.re-wrenches.org> <b>On Behalf Of </b>Drake<br><b>Sent:</b> Friday, August 24, 2018 4:52 PM<br><b>To:</b> RE-wrenches <re-wrenches@lists.re-wrenches.org><br><b>Subject:</b> Re: [RE-wrenches] Forced air Furnace<o:p></o:p></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>A wood stove heats the house, and will be the primary source of heat. An un-vented propane wall heater is installed and can heat the small, earth bermed, well insulated structure. A furnace will be a nice supplement, and will quickly pay for itself in insurance savings. During even a moderately cloudy day, it will be fine, but will not be used much on batteries. Still, I'd like as efficient a model as possible. <br><br>If I can find a unit with a 400 W draw, like the one in our on grid house, that would be adequate. The specifications I've found on the blower motors are sketchy. I will likely need to order it on line (or take a trip to a neighboring city), so reading the nameplates might not be so easy. <br><br>Does anyone know how to get accurate data on furnace blower motors? <br><br>Thanks,<br><br>Drake <br><br>At 01:59 PM 8/24/2018, you wrote:<br><br><o:p></o:p></p><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><p class=MsoNormal style='margin-bottom:12.0pt'>Content-Type: multipart/alternative;<br> boundary="------------914ACDD867C6488AACA07365"<br>Content-Language: en-US<br><br>I always try to talk the client into hydronic heating with ECM drive circulation pumps. They do make ECM drive blower motors that can be retrofitted in some furnace systems. Overall, its just a bad combination off grid: the worse the weather is the less PV production you have, and this corresponds to the same time that the furnace is operating 12 hours/ night. They are either running the generator a bunch, or waking up in the morning to a cold house with the power off, and dead batteries. If its an AC coupled system, they won't even have any PV production the next morning either. This is another reason AC coupled is not a great idea, or at least you need to always have some DC coupled PV as well, but I digress......<o:p></o:p></p><pre>Ray Walters<o:p></o:p></pre><pre>Remote Solar<o:p></o:p></pre><pre>303 505-8760<o:p></o:p></pre><p class=MsoNormal>On 8/23/18 5:43 PM, Dana wrote:<br><br><o:p></o:p></p><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><p class=MsoNormal>Drake,<br>All the conventional units I have amp clamped over the years are pushing 900-900+ watts per hour. I do not recommend them ever & to date I have never found a lower wattage blower. I would assume that a permanent magnet motor would fit this suggestion, but I have not found one.<br>For off grid I recommend: Radiant floor heat first and hot water base board second long before hot air. Air is a better insulator than a heat transfer agent.<br>The new ECM (electronically commutated motors) pump motors are basically at DC permanent magnet motor power draws [Taco & Grundfoss] these days.<br> <br>Best of luck with this one.<br> <br>----------------------------------------------------------------------------<br>Dana Orzel Great Solar Works, Inc. <br><b>C - 208.721.7003 <a href="mailto:dana@solarwork.com">dana@solarwork.com</a><br></b>Idaho Contractor - # 028765 Idaho PV # 028374<br>NABCEP # 051112-136 <a href="http://www.solarwork.biz">www.solarwork.biz</a><br><u>"Responsible Technologies for Responsible People since 1988" <br></u><b>P</b> Please consider the environment before printing this email.<br> <br> <br><b>From:</b> RE-wrenches <a href="mailto:re-wrenches-bounces@lists.re-wrenches.org"><re-wrenches-bounces@lists.re-wrenches.org></a> <b>On Behalf Of </b>Drake<br><b>Sent:</b> Thursday, August 23, 2018 2:37 PM<br><b>To:</b> RE-wrenches <a href="mailto:re-wrenches@lists.re-wrenches.org"><re-wrenches@lists.re-wrenches.org></a><br><b>Subject:</b> [RE-wrenches] Forced air Furnace<br> <o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:12.0pt;margin-left:.5in'>Hello Wrenches,<o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:12.0pt;margin-left:.5in'>What is the best choice for a propane, forced air furnace for an off grid house? We would prefer one that doesn't have a phantom load, although the transformer for the thermostat may not be avoidable. Low blower current would be preferable. The furnace AC will be powered by a Magnum 4448 PAE.<o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:12.0pt;margin-left:.5in'>Thank you,<o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:12.0pt;margin-left:.5in'>Drake <o:p></o:p></p><p class=MsoNormal style='margin-left:.5in'>Drake Chamberlin<o:p></o:p></p><p class=MsoNormal style='margin-left:.5in'>Athens Electric LLC<o:p></o:p></p><p class=MsoNormal style='margin-left:.5in'>OH License 44810<o:p></o:p></p><p class=MsoNormal style='margin-left:.5in'>CO License 3773<o:p></o:p></p><p class=MsoNormal style='margin-left:.5in'>NABCEP Certified Solar PV <o:p></o:p></p><p class=MsoNormal style='margin-left:.5in'>740-448-7328<o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:12.0pt;margin-left:.5in'><a href="http://athens-electric.com/">http://athens-electric.com/</a> <o:p></o:p></p><p class=MsoNormal style='margin-bottom:12.0pt'> <br><br><br><o:p></o:p></p><pre>_______________________________________________<o:p></o:p></pre><pre>List sponsored by Redwood Alliance<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>List Address:<o:p></o:p></pre><pre><a href="mailto:RE-wrenches@lists.re-wrenches.org"><o:p></o:p></a></pre><pre><span class=MsoHyperlink><a href="mailto:RE-wrenches@lists.re-wrenches.org">RE-wrenches@lists.re-wrenches.org</a></span><o:p></o:p></pre><pre><o:p> </o:p></pre><pre>Change listserver email address & settings:<o:p></o:p></pre><pre><a href="http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org"><o:p></o:p></a></pre><pre><span class=MsoHyperlink><a href="http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org">http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org</a></span><o:p></o:p></pre><pre><o:p> </o:p></pre><pre>List-Archive:<o:p></o:p></pre><pre><a href="http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html"><o:p></o:p></a></pre><pre><span class=MsoHyperlink><a href="http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html">http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html</a></span><o:p></o:p></pre><pre><o:p> </o:p></pre><pre>List rules & etiquette:<o:p></o:p></pre><pre><a href="http://www.re-wrenches.org/etiquette.htm"><o:p></o:p></a></pre><pre><span class=MsoHyperlink><a href="http://www.re-wrenches.org/etiquette.htm">www.re-wrenches.org/etiquette.htm</a></span><o:p></o:p></pre><pre><o:p> </o:p></pre><pre>Check out or update participant bios:<o:p></o:p></pre><pre><a href="http://www.members.re-wrenches.org"><o:p></o:p></a></pre><pre><span class=MsoHyperlink><a href="http://www.members.re-wrenches.org">www.members.re-wrenches.org</a></span><o:p></o:p></pre><pre><o:p> </o:p></pre></blockquote><p class=MsoNormal><br>_______________________________________________<br>List sponsored by Redwood Alliance<br><br>List Address: <a href="mailto:RE-wrenches@lists.re-wrenches.org">RE-wrenches@lists.re-wrenches.org</a><br><br>Change listserver email address & settings:<br><a href="http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org">http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org</a> <br><br>List-Archive: <a href="http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html">http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html</a> <br><br>List rules & etiquette:<br><a href="http://www.re-wrenches.org/etiquette.htm">www.re-wrenches.org/etiquette.htm</a><br><br>Check out or update participant bios:<br><a href="http://www.members.re-wrenches.org/">www.members.re-wrenches.org</a><o:p></o:p></p></blockquote></div></body></html>