<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class="">List: cc Norbert</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>I am assuming that Norbert either intended this to go to the full list or won't mind my forwarding to the whole group. The material at the end on stove testing in New Zealand is particularly relevant (I was surprised at the spread of test results - and at the importance of the biomass fuel content on emission levels).</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>I won't add much this time since Norbert has added a lot already. But I do want to further explore how there can be simple mods so that these massive stone "artworks" can also make char. So my only question for Norbert is how much added cost there would be if your present logs of 150-200 mm diameter also had a similar length (maybe 3-4 times as many cuts on a log). I believe a TLUD design could work with such fuel. To be explored.</div><div class=""><br class=""></div><div class="">Ron</div><div class=""><br class=""></div><div class=""><br class=""></div><br class=""><div><br class=""><blockquote type="cite" class=""><div class="">Begin forwarded message:</div><br class="Apple-interchange-newline"><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;" class=""><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif; color:rgba(0, 0, 0, 1.0);" class=""><b class="">From: </b></span><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif;" class="">Norbert Senf <<a href="mailto:norbert.senf@gmail.com" class="">norbert.senf@gmail.com</a>><br class=""></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;" class=""><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif; color:rgba(0, 0, 0, 1.0);" class=""><b class="">Subject: </b></span><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif;" class=""><b class="">Re: [Stoves] Stoves Digest, Vol 95, Issue 26 top lit updraft burning</b><br class=""></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;" class=""><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif; color:rgba(0, 0, 0, 1.0);" class=""><b class="">Date: </b></span><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif;" class="">July 28, 2018 at 6:34:32 AM MDT<br class=""></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;" class=""><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif; color:rgba(0, 0, 0, 1.0);" class=""><b class="">To: </b></span><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif;" class="">"Ronal W. Larson" <<a href="mailto:rongretlarson@comcast.net" class="">rongretlarson@comcast.net</a>><br class=""></span></div><br class=""><div class=""><div dir="ltr" class=""><div class="gmail_extra"><div class="gmail_quote">On Fri, Jul 27, 2018 at 9:20 PM, Ronal W. Larson <span dir="ltr" class=""><<a href="mailto:rongretlarson@comcast.net" target="_blank" class="">rongretlarson@comcast.net</a>></span> wrote:<br class=""><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div style="overflow-wrap: break-word;" class=""><b class="">(snip)</b><div class=""><div class=""><b class=""><span class="gmail-m_-3228795885440360360Apple-tab-span" style="white-space:pre-wrap"> </span>1a. Because they can burn whole logs, the cost per unit of supplied energy (absent initial cost) must be lower than any other fuel source. </b></div></div></div></blockquote><div class=""><br class=""></div><div class="">We can burn large logs (150mm - 200mm diameter) with low emissions. PM is same range as pellet stoves. The cold start and getting everything up to temperature is the main technical issue. Efficiency is roughly the same (75% HHV, 80% LHV) as a good EPA stove, so fuel consumption per BTU would be similar. The low temperature radiant heating has some additional benefits compared to hot air.</div><div class=""> <br class=""></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div style="overflow-wrap: break-word;" class=""><div class=""><div class=""><b class=""><span class="gmail-m_-3228795885440360360Apple-tab-span" style="white-space:pre-wrap"> </span>1b. Do some MH's ever recommend use of coal?</b></div></div></div></blockquote><div class=""><br class=""></div><div class="">In Poland, for example, they use coal and therefore have grates. This causes air quality problems in urban areas.</div><div class="">I have a friend from Ukraine, where wood was scarce and they used it only for starting the coal.</div><div class=""><br class=""></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div style="overflow-wrap: break-word;" class=""><div class=""><div class=""><b class=""><span class="gmail-m_-3228795885440360360Apple-tab-span" style="white-space:pre-wrap"> </span>Being able to use stored energy must be a big selling point, in terms of time spent in keeping a house warm. </b></div></div></div></blockquote><div class=""><br class=""></div><div class="">That's the main benefit. We've heated exclusively with wood for 45 years, and my wood heating chores amount to roughly 10 minutes per day. As a bonus, my wife and I get to watch a nice big fire for 2 hrs every day. Having started out as a mason building fireplaces, this is much more successful as a fireplace than the traditional open one.</div><div class=""> <br class=""></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div style="overflow-wrap: break-word;" class=""><div class=""><div class=""><b class=""><span class="gmail-m_-3228795885440360360Apple-tab-span" style="white-space:pre-wrap"> </span>1c. </b><b class="">Is there ever a cooking application (besides ovens) where mass is so important (question for everyone). </b></div></div></div></blockquote><div class=""><br class=""></div><div class="">We have an oven option, and use ours a lot. It is a free byproduct of the heating function, and is different from having a dedicated oven that you would fire separately, although some people incorporate that style as well. We also have a cookstove, which is a separate appliance and requires a separate flue. In Hungary, it is traditional to add a brick "heating wall" between the cookstove and the chimney. Crispin is looking at a version of this in Mongolia(?) I believe.</div><div class=""> <br class=""></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div style="overflow-wrap: break-word;" class=""><div class=""><div class=""><b class=""> </b></div><div class=""><b class=""><span class="gmail-m_-3228795885440360360Apple-tab-span" style="white-space:pre-wrap"> </span>1d. What heating efficiency is claimed by MHA members? (can you get to 90%?)</b></div></div></div></blockquote><div class=""><br class=""></div><div class="">HHV we realistically get 75% (82% LHV). You can get roughly 5% more with a system from Russia called "double bell" that takes advantage of buoyancy rather than channeling of the gases. <br class=""></div><div class=""><br class=""></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div style="overflow-wrap: break-word;" class=""><div class=""><span class="gmail-"><blockquote type="cite" class=""><div class=""><div dir="ltr" class=""><div class="">Batch fuel loads are 15 - 30 kg., once or twice per day. Biochar has never been a consideration, and I only got interested in it recently.</div></div></div></blockquote></span><b class=""><span class="gmail-m_-3228795885440360360Apple-tab-span" style="white-space:pre-wrap"> </span>[RWL2a: Which is why I have to keep this dialog going a bit longer</b><span class="gmail-"><br class=""><blockquote type="cite" class=""><div class=""><div dir="ltr" class=""><div class=""><br class=""></div><div class="">They typically have a flue damper which needs to be closed to retain the heat. This means all the charcoal has to be burned, or you risk carbon monoxide poisoning. Some countries like Germany and Austria don't permit flue dampers due to the potential safety issue.</div></div></div></blockquote><span class="gmail-m_-3228795885440360360Apple-tab-span" style="white-space:pre-wrap"> </span></span><b class="">[RWL2b. I have read that burning charcoal (not making it) is a favored form of suicide; via CO.</b></div></div></blockquote><div class=""><br class=""></div><div class="">I had a Finnish neighbour who told me that as children, they were taught "blue flame means death". <br class=""></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div style="overflow-wrap: break-word;" class=""><div class=""><br class=""><blockquote type="cite" class=""><div class=""><div dir="ltr" class=""><div class=""><br class=""></div><div class="">With an underwire air system (grate), burning up charcoal is easy, but underfire air was found to be dirty once we started measuring PM and CO.</div></div></div></blockquote><span class="gmail-m_-3228795885440360360Apple-tab-span" style="white-space:pre-wrap"> </span><b class="">[RWL3: Apologies for "underwire" - my computer doesn't have "underfire" in its dictionary. You are giving here one of the main advantages of making and saving char in a cookstove - this is a topic broader than efficiencies.</b><span class="gmail-"><br class=""><blockquote type="cite" class=""><div class=""><div dir="ltr" class=""><div class=""><br class=""></div><div class="">For the last couple of years I have experimented with using an airtight system, like the Austrians, that allows the combustion to be stopped by shutting off the combustion air and also preventing flow through the chimney. This can be done at any time once the batch has burned the volatiles and is into charcoal mode. This is a huge convenience, because you can walk away and don't have to worry about closing a flue damper too early. Coincidentally, the tighter you can manage to make it, the more charcoal you can make. The next morning, there may still be some live coals and I scoop all the remains into a metal ash bucket with a tight lid, that extinguishes everything. Somewhat similar to the bottom part of a Kon Tiki kiln. Charcoal yield is roughly 5% by weight.<br class=""></div></div></div></blockquote><span class="gmail-m_-3228795885440360360Apple-tab-span" style="white-space:pre-wrap"> </span></span><b class="">[RWL4: I suppose you are giving a reason (difficulty in achieving a tight fit) some TLUD cookstove manufacturers choose to burn up their char. I like the solution achieved by Julien Winter of a burnable string (sort of a fuse) that dumps the char automatically and immediately when the pyrolysis front hits the bottom.</b></div><div class=""><b class=""><span class="gmail-m_-3228795885440360360Apple-tab-span" style="white-space:pre-wrap"> </span>We promoting char-making stoves would not be satisfied with 5% (always hear more than 15% and sometimes up to 25% or more - by weight). If I wanted a MH that maximized char production (to make more money while heating), what char-production do you think might be achievable? </b></div></div></blockquote><div class=""><br class=""></div><div class="">Maybe 10% - 15% using existing techniques? To max it out maybe you'd be looking at something like an airtight boiler made from refractory lined steel, set up somehow to facilitate the handling of the charcoal from a batch process. In my case, the fireplace function with a large glass door is important, and probably the hardest thing to get airtight.</div><div class=""><br class=""></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div style="overflow-wrap: break-word;" class=""><div class=""><b class=""><span class="gmail-m_-3228795885440360360Apple-tab-span" style="white-space:pre-wrap"> </span>Gordon West and Bill Knauss are doing heating (not cooking) with a continuous TLUD design - but need (as do most all) pellets or maybe chips - vs your use of much cheaper logs. So you might have a leg up in costs per kg of char production - but they might (?) have a leg up in being able to produce more char per log. Any thoughts here on economics?<br class=""></b></div></div></blockquote><div class=""><br class=""></div><div class="">I made about 300 lb of charcoal last winter from 7000 lb of cordwood (20% moisture). There is a big push in the US Northeast from New York State and others to push pellet biomass for domestic and small scale commercial. Cordwood is considered too problematical with PM emissions. For EPA certified woodstoves, the PM emissions are very operator dependent, and there is still a big debate about this. The New Zealanders have done some really cool field and laboratory studies of certified and uncertified pellet and cordwood stoves, using the Condar portable dilution tunnel that we use.<br class=""><a href="http://heatkit.com/docs/emissions-testing-wood-burners-tokoroa-jun07.pdf" class="">heatkit.com/docs/emissions-testing-wood-burners-tokoroa-jun07.pdf</a><br class=""></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div style="overflow-wrap: break-word;" class=""><div class=""><b class=""></b><span class="gmail-"><blockquote type="cite" class=""><div class=""><div dir="ltr" class=""><div class=""><br class=""></div><div class="">Contraflow refers to a particular way of running the internal heat exchange channels, ie downdrafting. It is native to Finland. Combustion is complete by this time. In the traditional Austrian system, the firebox has less height and immediately downdrafts before entering additional heat exchange flue channels. With this setup you get very good mixing in the flames in the downdraft channel this way.</div></div></div></blockquote><span class="gmail-m_-3228795885440360360Apple-tab-span" style="white-space:pre-wrap"> </span></span><b class="">[RWL5: I still haven't visualized the geometry. Can you send us to a technical paper on this? I think your use of "down drafting" here does not mean airflow through the fuel bed, so I am not sure how this might fit into char-making.</b></div></div></blockquote><div class=""><br class=""></div><div class="">Downdrafting in our case refers to heat exchange flue channels after the firebox, and not to combustion in the firebox:<br class=""></div><div class=""><br class=""></div><div class="">Austrian stove:<br class=""><a href="http://www.mha-net.org/graphics2/18072801.JPG" class="">http://www.mha-net.org/graphics2/18072801.JPG</a></div><div class=""><br class=""></div><div class="">Finnish contraflow heater:<br class="">
<a href="http://www.mha-net.org/graphics2/18072802.JPG" class="">http://www.mha-net.org/graphics2/18072802.JPG</a></div><div class=""><br class=""></div><div class="">(snip)<br class=""></div></div>-- <br class=""><div class="gmail_signature">Norbert Senf<br class="">Masonry Stove Builders<br class="">25 Brouse Road, RR 5<br class="">Shawville Québec J0X 2Y0<br class="">819.647.5092<br class=""><a href="http://www.heatkit.com/" target="_blank" class="">www.heatkit.com</a></div>
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