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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>Have you or the client looked into the drainwater heat recovery units? They make both a vertical and horizontal mounted version. They just help recover the waste heat from shower water going down the drain.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>My understanding is that economically they are barely past the breakeven point when considering offsetting grid power. If using PV costs as the benchmark, the economics would be better. If somehow this is off grid, then I’d say it’s a home run. (Hopefully though this is not an all-electric off-grid building.)<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>The main benefit, as far as I understand it, is that you can get by with a smaller unit, with a smaller heating element to perform the same task, OR you can get much longer showers from the same sized unit. Depending on the clients goals, this might be a useful tool to bring into the situation.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Here are two brand names that I know of.<o:p></o:p></p><p class=MsoNormal>Vertical mount: renewability<o:p></o:p></p><p class=MsoNormal>Horizontal mount: ecodrain<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I have not used these products, so I cannot endorse any of them, just though it may be worth consideration.<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></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> Thursday, March 15, 2018 1:00 PM<br><b>To:</b> RE-wrenches <re-wrenches@lists.re-wrenches.org><br><b>Subject:</b> Re: [RE-wrenches] Electric Water kWh/ person<o:p></o:p></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>This discussion has been a great help. The house is built and the plumbing is in, but could be modified. Wood stoves are not a likely solution. I think we need a different water heating strategy.<br><br>Thank you all!<br><br>Drake <br><br><br><br>At 09:21 AM 3/15/2018, you wrote:<br><br><o:p></o:p></p><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><p class=MsoNormal>Content-Type: multipart/alternative;<br> boundary="------------EE4E9806B711DEF636076840"<br>Content-Language: en-US<br><br><span style='font-family:"Verdana",sans-serif'>This is what I came up with:<br></span><br><span style='font-family:"Verdana",sans-serif'>The calculation is Q = mcp delta T<br></span><br><span style='font-family:"Verdana",sans-serif'>Water Temp out = 120<br></span><br><span style='font-family:"Verdana",sans-serif'>Water Temp in = ground source Temperature @ 50F?<br></span><br><span style='font-family:"Verdana",sans-serif'>delta T = 70F<br></span><br><span style='font-family:"Verdana",sans-serif'>m = mass flow rate. ASHRAE is the source for this. 20gals per person per day = 20 gallons x 8.34 lbs/gallon = 167lbs/day/person<br></span><br><span style='font-family:"Verdana",sans-serif'>cp = 1 BTU/lb-degree F<br></span><br><span style='font-family:"Verdana",sans-serif'>Q = 167 x 1 x 70 = 11,676 BTU/day/person<br></span><br><span style='font-family:"Verdana",sans-serif'>Divide this by the efficiency of the water heating system (I'll assume = .86) =11,676/.86 = 13, 577 BTU/person/day<br></span><br><span style='font-family:"Verdana",sans-serif'>convert to kWh if necessarym 13,577/3412 = ~4 kWh/person/day, 120 kWh/month<br></span><br><span style='font-family:"Verdana",sans-serif'>I checked this against one month and it seems reasonable. <br></span><br><span style='font-family:"Verdana",sans-serif'>Website assuming ~3.5 family size comes up with @ 400kWh per month. They approached it another way with assuming run times.<br></span><br><span style='font-family:"Verdana",sans-serif'><a href="https://www.google.com/search?safe=active&source=hp&ei=Z3KqWvXiNsGb5wKJ2Kf4DA&q=electric+water+heater+use+annual+consumption&oq=electric+water+heater+use+annually&gs_l=psy-ab.1.2.33i22i29i30k1l3.279.9222.0.12475.35.19.0.7.7.0.451.2360.0j6j4j0j1.11.0....0...1c.1.64.psy-ab..18.16.1952.0..0j0i67k1j0i131k1j0i22i30k1.0.CiU8wYZigpI">https://www.google.com/search?safe=active&source=hp&ei=Z3KqWvXiNsGb5wKJ2Kf4DA&q=electric+water+heater+use+annual+consumption&oq=electric+water+heater+use+annually&gs_l=psy-ab.1.2.33i22i29i30k1l3.279.9222.0.12475.35.19.0.7.7.0.451.2360.0j6j4j0j1.11.0....0...1c.1.64.psy-ab..18.16.1952.0..0j0i67k1j0i131k1j0i22i30k1.0.CiU8wYZigpI</a> <br></span><br><span style='font-family:"Verdana",sans-serif'><br>Chris<br></span><br><span style='font-family:"Verdana",sans-serif'><br></span><br><br>On 3/15/2018 8:09 AM, Mike Kocsmiersky 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'>Barton makes a good point with regards to the incoming ground water temperature and the amount of heat required to bring it up to shower temp. My recollection is that ASHRAE states 20gal/person/day for the first 2 people, then 15gpd or 12gpd thereafter. However those rates vary wildly with consumers, from those that never bathe to the high schooler that needs 3 showers a day. In the northeast water heating can be up to 19% of the total household energy load for the year. Also, I would recommend the air source heat pump water heaters if you have significant humidity or an on demand unit. Water tanks are typically under insulated and can lose 2kWh/day in standby losses.<br> <br>Mike Kocsmiersky<br>Principal<br>Spirit Solar Inc.<br>(413) 734-1456<br> <br> <br> <br><b>From:</b> Barton Churchill [<a href="mailto:barton@solarips.com">mailto:barton@solarips.com</a>] <br><b>Sent:</b> Wednesday, March 14, 2018 7:31 PM<br><b>To:</b> RE-wrenches<br><b>Subject:</b> Re: [RE-wrenches] Electric Water kWh/ person<br> <br>You first need to know your ground temperature. Then figure a delta to 100 or so degrees. Most but not all showerheads flow 2.5gpm and showers are typically 10 minutes. You can then find a calculator online to calculate how many Btus are required to raise water temp for your delta per gallon. Convert to kWh, add some contingency and you should be good. <br><br>On Wednesday, March 14, 2018, <<a href="mailto:drake.chamberlin@redwoodalliance.org"> drake.chamberlin@redwoodalliance.org</a>> wrote:<br>Hello Wrenches,<br><br>Is there a good way to estimate the power that will be consumed for electric water per person per day? We are estimating the amount of power that will be used by an all electric duplex, and the water heater amount seems high. The current model we have claims 3493 kWh/ year per 26 gallon tank will be consumed. With the two units, that would add up to 6986 kWh / year for hot water, pushing the system size to humongous for a 1300 ft sq building. <br><br>Does that seem high? There will be a maximum of 2 people per unit. <br><br>The owner is considering going to 115 V units with a 15 gallon tanks. I think the smaller tank would help, but it would seem that the amount of hot water consumed would be the main issue. <br><br>How can we get a good estimate for a per person energy usage for electric hot water? Any other suggestions are welcome.<br><br>Thank you,<br><br>Drake<br><br><br><br>-- <br>-- <br>Barton Churchill<br>406.587.5295 <br>2430 North 7th Bozeman, MT 59715<br><a href="http://www.solarips.com/">www.solarips.com</a><br><img border=0 width=100 height=100 style='width:1.0416in;height:1.0416in' id="_x0000_i1025" src="cid:7.1.0.9.0.20180315124406.058de878@redwoodalliance.org.2" alt="Image removed by sender."><br> <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><br><span style='font-size:10.0pt'> Christopher Warfel, PE<br> ENTECH Engineering, Inc.<br>PO Box 871, Block Island, RI 02807<br> (401)466-8978</span><br> <br><a href="http://entech-engineering.com"><span style='text-decoration:none'><img border=0 width=201 height=89 style='width:2.0937in;height:.927in' id="_x0000_i1026" src="cid:7.1.0.9.0.20180315124406.058de878@redwoodalliance.org.3" alt="EEI logo"></span></a> <br><br><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>