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I live in the upper reaches of Michigan and I'm looking for ways to save a few bucks on heating this winter and winters coming. Lets put aside any legal precautions, local building codes or insurance coverage issues. What I'm interested in is the design and construction of an efficient EPA-certified-style non-catalytic Wood stove/furnace.Has anybody looked into this? I'm somewhat interested in the design constraints for a secondary combustion chamber, heat-output and how to size accordingly, and any other tricks, design theories, etc to increase the efficiency.I'm not looking for a 55gal barrel or water heater converted, but rather lets start from a clean slate, and go through the motions to design a good compromise of ease of build, cost of materials, efficiency of burn and even consider asthetic properties.
Reply:how much space do you want to heat with this ?...zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:I'm looking for supplementary heat for approximately 1700 sq/ft IIRC. I currently run a 55,000 BTU NG Forced Air Furnace, possibly just used for backup? I guess in theory I'd like it to be big enough to do basically all the heating, granted the efficiency is enough to where I'm not loading wood all the live long day, and I can get enough who-house airflow to be comfortable. At the moment, the forced air furnace has virtually no ductwork, relying on convection and luck to heat the outer reaches of the house. This is something else I'd like to possibly address with a wood fired stove/furnace of some sort.
Reply:Originally Posted by chicksdigwagonsI'm looking for supplementary heat for approximately 1700 sq/ft IIRC. I currently run a 55,000 BTU NG Forced Air Furnace, possibly just used for backup? I guess in theory I'd like it to be big enough to do basically all the heating, granted the efficiency is enough to where I'm not loading wood all the live long day, and I can get enough who-house airflow to be comfortable. At the moment, the forced air furnace has virtually no ductwork, relying on convection and luck to heat the outer reaches of the house. This is something else I'd like to possibly address with a wood fired stove/furnace of some sort.
Reply:No offense zap, but this is exactly the type of response I was trying to avoid. Lets say, money was not an issue (but it always is), I had a hearty supply of material for free or cheap, and I was stubborn.I'm honestly mostly interested in the design theories behind the stove more than the welding involved which isn't a problem. Perhaps this is more of an off-topic subject?
Reply:no i think this topic belongs right here..sorry about my reply but thats just what i would do..no offense taken i once made a wood stove out of 2 rear wheel "wells" from a oil delivery truck..it was huge..heated the whole house for the owners......zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Your opinion has been dually noted I've been drawing up some basic sketches of what I think would be in the ballpark for the right size for what I'm looking for. I think for total stove materials I can get out under $250 including steel, firebrick, etc. To buy a comparable sized, featured stove at Northern Tool would put me in the $500 range, not including shipping. Haven't looked locally but it might be worth a shot.I'm still hung up on the concepts of baffling, creating the secondary combustion chamber, and most of all introducing combustion air. I realize this isn't exactly rocket science, but the engineering behind how to best build it is sobering. I'm also in the early conception stages of an automatic combusion air control based on a thermocouple reading of combustion temp and some other variables.
Reply:I found this while perusing old threads on AWS:http://www.motherearthnews.com/top_a..._35__Or_Less__HTH,Mike
Reply:Thanks, I've come accross that several times over the years. And if you notice, I specifically said I didn't want anything involving 55gal barrels or old water heaters But that article was the original inspiration. If I was confident I could find water heaters with steel tanks in good condition I'd at least recycle some of the material in my project.But to just build it like that... That'd just be too easy.
Reply:20 years ago when I was in gradeschool we lived in NW PA - right in the snowbelt the perfect distance from Lake Erie in Warren. We lived on top of a hill about 1200 feet higher than the town and heating was definitely an issue. The house was built with a water base board heater that had a boiler fired by natural gas. My dad installed a wood fired boiler that was very homebuilt looking - the whole housing was simply fabricated out of 1/4" steel sheet. It stood about 5' tall, 2.5' wide, and 3' deep, and the heat exchanger was a unit that slid into the top from the back. As I recall it looked fabricated out of steel plate with a bunch of tubes going straight up through it for the smoke / heat to rise up through. It had a thermostatically controlled damper on it, and was completely self operating short of stoking once in the morning and once at night each day. It kept the ~1500 sqft house around 80 all winter. He cut the firewood 32" long, and split it fairly thick to about 8 - 10" thick so they would burn longer. Seems like it was a fairly efficient system - specially with the thermostatic damper control. And this was early 80's technology... Not sure it would meet today's epa standards, but I do know it is STILL in use today. Ok, maybe not TODAY, but when winter comes it'll be burning.BTW - the only problems it ever had were occasional water leaks in the heat exchanger. He pulled it out the first time - lotsa fun - but after that had a friend stick weld it in place. I can still picture that guy with his head arms, and torso squeezed inside the firebox! No thanks!!!
Reply:Interesting topic, I'd definately like to find an alternative source than spending $2000 this winter on Kerosene for my hydronic base-board heat.John - fabricator extraordinaire, car nut!- bleeding Miller blue! http://www.weldfabzone.com
Reply:Originally Posted by WannabeI found this while perusing old threads on AWS:http://www.motherearthnews.com/top_a..._35__Or_Less__Mike
Reply:Hmm, some interesting input from a wood burning source: Read the last FAQ - http://www.woodheat.org/contact/faq.htmJohn - fabricator extraordinaire, car nut!- bleeding Miller blue! http://www.weldfabzone.com
Reply:Originally Posted by MicroZoneJust read that article, I'm wondering if anyone has sent away for their $6 plans. They say they work wonderful and the mother-earth folk have the plans.
Reply:That would be great, thanks for sharing.John - fabricator extraordinaire, car nut!- bleeding Miller blue! http://www.weldfabzone.com
Reply:I guess according to that article, the heater I built is no good. It heats the shop up, why is that no good. I thought it was a good design I came up with. It has a box built onto the back and heat ducts built into the wood chamber and vents out the front. It has a squirrel cage blower on the back to push the hot air through. I'll try to post some pics later.DewayneDixieland WeldingMM350PLincoln 100Some torchesOther misc. tools
Reply:A book that you might find very interesting, but may have difficulty finding, is "Proceedings Residential Wood & Coal Combustion Specialty Conference"Edited by:East Central SectionAir pollution Control AssociationMarch, 1982It is a 300 page collection of papers by scientists involved in optimizing wood and coal burning stoves for maximum efficiency and minimum emission of pollution. Lots of fairly technical stuff, but also discussion of the very beneficial effect of refractory linings of the combustion chamber (firebrick), secondary combustion air, draft control, etc.I tried several book search engines and came up with nothing. Perhaps the Air Pollution Control Association can help. Since this was the 1982 conference proceedings, I imagine there are proceedings from other years' conventions, also.I picked my copy up at a used book store for $11, just in case I needed it someday.awright
Reply:I think a triple pass design like modern oil burners might be worth considering. Also, using outside air for combustion would add to the efficiency. There is a point of diminishing returns. If you extract too much heat from the process the stove will not draft properly. Insulating the chimney flue might help here, however, you once again reach a point of diminishing returns. Adding combustion air to the upper chambers would help draft and would assist in burning the gasses.RonL
Reply:awright:Thanks tremendously, you've pointed me in the right direction with your information. With the right wording I've stumbled upon a number of articles that are technical in nature and exactly the type of things I need to study.RonL:You bring up a very important point that I've been struggling with for the past several days now. Finding the balance between extracting as much heat from the combustion process as possible and still maintaining proper draft. It seems secondary combustion is a good step in the right direction, as you're basically burning particles/gasses that would otherwise go up and out the flue. Problem is, in order to start and sustain secondary combustion you need a relatively high temperature, to the tune of 12-1300 degrees from what I've been reading. This requires a hot, fast fire and a good thick heat storing stove. Also, as you mentioned, you need to supply it with a secondary source of combustion air as by the time the flue gasses reach the secondary combustion area the O2 is all used up. This is easy to do in theory, but a major consideration is adding too much air or too cool of air. I'm not entirely sure what you mean by triple pass design, though the design I sketched up has three levels and might be similar to what the oil burners use.Pardon the elementary Microsoft Paint drawing, but this is the general concept for starters: I'm also getting started on high temp ceramic coatings like they use in automotive exhausts. I think they could be effectively applied to this application as well. With the combination of firebrick, strategic use of ceramic insulating coatings, multiple outer walls and baffles I think I could still cheaply build an efficient inexpensive woodburner.
Reply:Originally Posted by littlefuzzI guess according to that article, the heater I built is no good. It heats the shop up, why is that no good. I thought it was a good design I came up with. It has a box built onto the back and heat ducts built into the wood chamber and vents out the front. It has a squirrel cage blower on the back to push the hot air through. I'll try to post some pics later.
Reply:That is essentially how my smaller wood stove looks inside. I would like to move up to a little larger unit. The smaller unit heats the house nicely but I'd like to have a larger one to fit bigger pieces of wood.John - fabricator extraordinaire, car nut!- bleeding Miller blue! http://www.weldfabzone.com
Reply:Originally Posted by MicroZoneThat is essentially how my smaller wood stove looks inside. I would like to move up to a little larger unit. The smaller unit heats the house nicely but I'd like to have a larger one to fit bigger pieces of wood.
Reply:The design you show is basically a triple pass. The first baffle would be open in the rear of the firebox. The second would be open in the front. Gasses would travel to the rear of the firebox, to the front of the second area, and to the rear and exit the flue pipe. ( Triple pass.) I'm thinking that maybe you could have a small diameter pipe coming up from the bottom rear of the firebox. This would add air to the gasses right at the point were they would be at there hottest. The gasses would then make the second and third passes. The air injection would have to be sized so as not to take away too much from the main draft. If there is too much unburned elements in the exhaust gas and it is too cool you get condensation of the flue gas and creosote buildup. That's the idea of a catalyst. It burns the flue gasses.
Reply:I helped a couple of fellas at work with the plans for a wood-fired boiler. Massive boiled. Here is the web site http://www.deb-design.com/prod01.htm Attached Images
Reply:here is my first one Attached ImagesHere are my two cents, with the proper disclaimers of responsibility. Back in the early 70's I took a course on woodburning airtight stoves because we were in the throes of oil embargos, sound familiar? One of the things the presenter stressed was the importance of a baffle, of secondary air and of a round, as in barrel, design. Well, I couldn't roll steel, but I could cut and weld, so i compromised on an octagon cross section. I had free 1/2" plate to work with, and made the cross section two feet across the flats, and 30" long, inside dimensions. Since I was working with a 10" flue I made the cross section of the area above the flat baffle plate the same as the cross section of the 10" flue pipe. Instead of welding the baffle plate in I tacked it to the back and supported it with a couple of beveled pieces welded to the upper 45° plates, so it could expand independantly of the body of the stove. The door, also octangular in shape was double thick with two seperate air plenums in between, one below for primary air and one above for preheated secondary air. It was sealed against the stove body with a flange on the door and some high temp ceramic fiber blanket. Independant adjustable draft control was on the front of the door for both primary and secondary air. Very little secondary air was necessary.She, we called her the iron pig because of the four legs that supported the fat body in my fireplace, heated my all electric 2500 square foot house on 5 cords of seasoned hardwood a year. One thing I learned was to get a good hot fire burning for an hour or so, and then throttle down the primary air draft; almost no smoke came from the chimney for the rest of the semi daily stoking. Obviously there was no catalytic converrter in the pipe, but they're available now.
Reply:I too live in the Upper Pen. of Mi.I have my own shop and have a design of my own for a boiler. I currently heat the shop with a forced air wood furnace that I got complete for $150.The air control damper is operated by the thermostat, and plenum air temp.You can email me questions @ [email protected] could take pics of the furnace I use later today.BrettBrett B & B Fabrication and Welding Inc.Spalding, MI.
Reply:I've been on vacation for two weeks and buried with work since I got back and I just came across this thread. I spent the better part of 13 years or so in manufacturing of several different wood stoves and pellet stoves. That ended about 10 years ago so I'm not really up on current designs and technology, but then again we never did get real hi-tech on the stoves I was involved with. Our stoves did meet EPA standards of that time nonetheless. It sounds as though a few of you have found some of the technical info you were looking for,so I doubt I can help much in that area.But maybe I can help with getting that knowledge put into a steel box. Let me know if you need any help with your stove build and I'll be glad to share what knowledge I have.
Reply:Thanks a bunch for all the input guys. I haven't forgotten about this project but was just blessed with a job finally after being unemployed for many months. I'll write up some of the things I've been working through on this, and some of the questions hopefully some of you can give some ideas concerning. Winter is approaching quickly!
Reply:I just got a nice wood heater cheap off ebay and found this thread. My heater has inlets for combustion air in the doors. I have been reading up on some designs, and was wondering how complicated installing a duct for fresh air would be. I have seen that by using fresh air(from outside the heated area) you gain more efficientcy(sp?). In talking with some much more experianced welders, I have found out some tips on making those 55gal drum heaters last. For instance, putting two inches of sand in the bottom of the combustion drum, will keep the barrells from wearing out. One of the guys said in the begining of his career, he heated his shop for 12 yrs with out replacing a barrell. Looking forward to hear from others on this thread. You guys are a wealth of information.
Reply:I to am interested in this. I will be in the shop a lot this winter. Luckily I am in Texas so it is not to bad.There are several statements about people claiming they wil post pictures. Does anyone still have plans to post their pictures?I only need to heat 400 sq ft and at the worst it gets into the 25 degree range around here and does not stay there long.I want a heater that will not spike the temp in the room but will absorb the heat and let it out slowly. Maybe heat up a bunch of rocks or something.Please post your pictures if you have them.
Reply:Plan to get picks just too BUSY and Forgot All about it.Shoot me a email and I'll try to get some on Friday when I'm in the shop. Probally need to run it anyhow , first winter storm is here. YAHOO!!!!!!!I love SNOW!!!!!BrettBrett B & B Fabrication and Welding Inc.Spalding, MI.
Reply:We heated a hunting cabin with a 55 gallon drum heater for years and never had to replace the barrel. The bottom was lined with fire bricks as far up the side as they would go with out falling. Then sand was spread over the bricks filling the cracks.Mother Earth news had an article about Thermal Mass stoves ,which I can't find at the moment , but as I recall had a number of suggestions on how to make stoves store heat.
Reply:set up a drip feed waste oil line into the furnace thats if you can get some waste oil the wood will last alot longer and burn alot hotter
Reply:Hey Bob, I just got a Harbor Freight ad in the mail. They have a small Vogelsgang heater on sale for 119.00. It should heat the place fine. One of the 55gal drum heaters would be cheaper and hold more wood but require assembly. The tractor supply here carries the Vogelsgang stuff too.
Reply:There are fire bricks and insulating fire bricks. The former will store heat, and take a great deal more BTUs to heat up. The latter will not store heat, and will allow stoves, furnaces, or kilns to come up to temperature more quickly.-Heath
Reply:I've owned & used several wood stoves in the past 35 years. An idea I've want to try on a horizontal box type stove is to run a 2" daimeter air supply pipe down each side of the firebox with spaced 1/4 -1/2 holes to admit air. All combustion air thru these pipes with adjustable disks at inlet for control. Think velocity increase at holes will act as forced draft creating a burning front the full length on each side??? Think this will promote even & thorough burning ???? I've seen downdraft top loaders with similar tubes coming down into firebox but have single outlet at bottom. They seem to work well. If you try this I'd like to hear how it works. An efficiency idea from 1800's logging camps in northern New England was to put the stove at one end of the bunkhouse & run the stovepipe horizontally the full length of the building extracting almost all of the heat. Of course these stoves were tended regularly, not filled in the am to run all day. MikeD74T
Reply:Heres the one i was looking at building, If you print the article you get some overall dimensions, and pretty good diagrams, plus 150,000 btu's to boot.http://www.motherearthnews.com/DIY/1...rning_Furnace_
Reply:metalworks,That is way overkill for my needs. I thought of making one using 3 brake drums from an 18 wheeler mated together like a pot bellied stove. Maybe put a shelf in the top and put some big rocks on it to help store heat.See the picture (sorry about the poor drawing skills). Attached Images
Reply:Bob - that looks like a great idea. I would put in a secondary chamber though...or make the rock area a secondary chamber by simlpy installing 2 plates opposing each other in that area.John - fabricator extraordinaire, car nut!- bleeding Miller blue! http://www.weldfabzone.com
Reply:I'm not following hwat you mean by two plates opposing eah other. Where would they be?I know nothing about secondary chambers
Reply:I wonder if anyone is considering the free ads in newspaper or internet site CRAIGSLIST.com.A lot of local folks here are swapping good wood stoves for gas. Those are usually stoves chosen for cosmetics so the old wood stoves are sometimes the expensive ones.
Reply:i'm not sure if this comes under the topic discussed...1.can we convert an oil fired heater to wood fired? what are the concerns and loop holes?2.lesser the moisture content in firewood, better to use it as fuel, because you dont have to use energy to evaporate/superheat the moisture. In practice it is seen that dry firewood doesnt give as much performace when compared with less moist firewood. what can be the possible causes/areas to think on?Does it have anything to do with the heat capacity (Cp) of wet air?
Reply:Well,Its getting to be that time of year again. The shop gets pretty cold too. Any more ideas on this subject?I do have a 30" and 18" s.s. tubes I rolled laying around, and both are 7 gauge. Been looking at the designs in the Lincoln project books.Any semi experts out there?I can get the double lined exhaust pipe from my Dad, just looking for good clean economical design. 600 acres behind the house full of old oaks.Ideas?Bill
Reply:Last winter I spent $5,000 on heating oil. I was running 3 furnaces, one in the house, one in my wood shop, and one in the weld shop. I have gone to electric forced air in the wood shop, and the house stays as is. Toward the end of last winter I bought a used "Fire-View" wood stove on ebay. It is round with the access door on the end. The "fire-view" name comes from the ability to flip a couple of handles and watch the fire through heat resistant glass (an feature I could care less about). The stove has a electric squirrel cage fan mounted on the back that takes cool air and circulates it around the rear radius of the stove. On the coldest day in March (in the 20's) it brought my weld shop up to 70 degrees in about 1/2 hour. I'm extremely pleased with the stove. It's not a large stove, takes little room, and really works great. I'm thinking of making another one, but leave the window out. Here's a link to see what these stoves look like. They no longer are made as they don't meet today's codes. In my shop I could care less about the code as I have plenty of draft air coming in.If any would like a set of pictures of my set up, I'll be pleased to post them.Here's the link: http://hearth.com/econtent/index.php...ew_Wood_Stove/ - 19k
Reply:I didn't see a mention of creasote anywhere. This can be a problem with high efficency wood stoves. Whatever you build needs to be built where it can be cleaned out occassionaly. A chimney fire is scary. Ask me how I know.
Reply:Bill, I was thinking of using S.S. also but after doing a little research . I have found that Stainless steel is not a very good conductor of heat it has 1/3 less thermal conductive then that of Carbon Steel (Mild steel ) . I am planning on building my own , but I have not completly figured out the design of the seconday burn yet. SantosLast edited by Santinis; 10-23-2008 at 12:48 PM.Reason: wrong word.
Reply:There may be good reasons for or against the use of SS for a wood stove (cost being a big one), but I don't think that the thermal conductivity of the metal is a practical issue. Don't forget that many advanced wood stoves are lined with firebrick or castable thermal insulation to decrease the rate of heat transfer (i.e., the conductivity) through the stove walls to the surroundings and thereby raise the temperature of the firebox for more efficient combustion and reduced emission of pollutants. Decreasing the conductivity of the metal shell by may actually be beneficial, if it has any practical effect at all.The last time I replaced the heat exchanger in my attic gas furnace I paid a premium for a SS exchanger and my subjective impression is that it has paid off handsomely in reduced replacement costs compared to the earlier mild steel units (I haven't actually tracked it).Emissivity of the surface may be of interest, and, not having researched it, I don't know how it differs between SS and mild steel. You can find it in handbooks or probably by googling it. Emissivity is an indicator of the efficiency of thermal radiation off a surface of a given temperature. That is, if you've got a stove at a given surface temperature, it gives off its heat both in the form of thermal radiation and in the form of convective heat transfer to the air passing over the surface. If the emissivity of the stove surface is low, less heat is lost through radiation and more heat is lost by convective heat transfer to the air.If you are sitting in front of the stove, you want thermal radiation to get that cozy feeling and warming of the air is, while still important, secondary. The thermal radiation also transfers heat directly to the various surfaces and objects in the room that can "see" the stove. The rest of the heat is transferred to the air that circulates around the room and eventually around the house, depending on your air flow conditions.On the other hand, if your wood stove is in the basement (unlikely, I grant), you are not particularly interested in thermal radiation and you want to transfer most of the heat to the air circulating around the house. I would guess that the emissivity of SS is lower than that of oxidized mild steel, but I'm not sure it is a big enough difference to be of concern. Intuition is not always a good indicator of emissivity.As a non-expert in stoves whose main experience is with a tiny 1 cubic foot cast iron stove in a mountain cabin, my bottom line would be cost and appearance instead of thermal conductivity. If I had access to SS plate at low cost, I could TIG it myself, and I didn't mind looking at a shiny stove with a multi-colored, bluish hue, I would not hesitate to go with SS. awright |
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发表于 2021-9-1 00:49:16