I’m just using local clay, it was produced by glaciers, should be a typical brick clay.
Yes, dry down, and bake, same concept as brick making. I’ve seen vids using plaster, that will for sure turn into powder in short order. The quartz sand is extremely heat resistant, reduces drying shrinkage, and toughens the clay. Charcoal or perlite serve to improve insulation, reducing density.
I been looking at vidios and some are useing mason morter to mix in the perlite, clay and charco refractory, does that change the drying time of loose any temp rateing ?? Good OR Bad ? Thanks.
Been hereing useing water too make fire brick mixes, is anyone useing regular mason mortor for the glue, or is there a problem useing glue makeing refractory cement, or are they just two different processes.? Allso i am woundering ig air crete would work with a perlite added too the mix.?
Hi Kevin,
I couldn’t tell what’s actually in a good mix. For a small amount I would buy a bag.
I have made my heat exchanger out of just over 1/8" thick 2&3/8" od water pipe. Will that last long from the heat, or should i build the refractory heat collector to heat the exchanger slower and less extreme temps.??
Filled with water the heat exchanger can take the heat just fine. Only it should never be fed with really cold water or the exhaust steam will condence and the heat exchanger will rust. Stay above 140 F.
Thanks jo’o i gess i will go ahead and nail it together and pour refractory when done ?
welding.
Hello wood gasifier heating boiler builders Jo,christijan and others, i need some ideas on ware the primary and secondary air is best located and preheated before located too the upper and lower compartments. ?? Thanks for the building ideas help.
Hi Kevin,
Secondary air should enter in the restriction. Preferably slots in the refractory. Helps to cool it and at the same time preheats the air some. Also it takes advantage of the venturi effect and rips air out in high speed which creates a good turbulent combustion enviroment.
Primary air can enter anywhere high in the woodbox/hopper. Make a big and lazy air entrance not to disturb the “pillow” of smoke on top and around the logs. The inlet should be piped down low on the outside not to let smoke out. Hopper vacuum is almost nothing.
Thanks again Jo that confirms what i was seeing, plus .mounting the air pusher low too keep smoke from rushing out, i hadent seen or thought of that, So now i will weld a big flat channel around my front door as the hole front plate on my wood burner is single, no water jacket, perfect spot for preheat air, while keeping the front door plate from over heating causing shrinking troubles later.No hot air preheat yet, just made the bottom chamber with at least enough room for 2-1/2" fire clay mix. i have too weld some 1/4" rods that a i have about 1" from the top side of burn chamber too help hold the refactory if it seperates from the metal, and thinking putting some sceen in center of the fire clay too maintain the contour when it may crack here and there.
the steel looks muddy black, though it is like new 3/16" plate all through the water jacket. the camera made shades and glare. Now waiting too go get some lime powder at menards building department , the lime mixed 50/50 with cement makes for heat resistant cement and works as a bonding material after the cement burns away or falls out from the heat. and clay mixed in allso, makes good morter for fire bricks and helps keep cast refactory bricks together.SO they say.Sorry l didnt post much here, been extremely buissy.
Here it is guys, first test fire. I had some problems with the refractory hearth otherwise it all went smooth.
I had no chimney so l blew air in with a shopvac to acheave draft.
The thing that struck me is how clean this thing burns. All the pics of the chimney are taken at full blast. No visible smoke what so ever.
The boiler output is about 25-30kw.
Wow, Kristijan! I’m impressed.
I think in vacuum mode it will burn even cleaner. Pushing primary air with the shopvac there was probably not much secondary air entering.
A couple of questions:
Will there be a hatch for primary air? Where does it enter the woodpile?
With the rear cleanout door vertical, how do you sweep the tubes?
Thank you. A lot of this all is on your expence. Without your help things wuldnt turn out so good for sure.
Correct. I guess some air gets drawn in by the venturi effect but not enough. Still it burned well.
No hach. For now. We decided to try eliminating the chimney all together and just extend the existing pipe ~ a meter, then with a strong fan and a good ejector provide the nesseeery draft and regulation. The reasons behind are the boiler will stand on its own near to the pool, in the open, and having a 7m pipe sticking out in the air, ancered with cables, just isnt practical. Second reason is shuld one of the water pumps fail, the boiler wuld overheat in minutes and since this must be a hands off system when in operation, such a failiure wuld be catastrophic. When using no natural draft, a safety overheating sweech can be hooked on the fan killing it if overheating is detected. This will quickly suffocate the burn.
Primary air enters on top 2 corners of the top door.
Well this was the most elegant solution for chimney position. A brush on a rigid steel cable shuld do the job of sweeping the heatex tubes.
Good too see you makeing good progress, hope my wood home heating gasifier works half that good. I wouder how hot it actually gets under the glow brick on the hot face part of the hearth chamber.
It was a long time ago I bought my Tarm wood gasification boiler probably just over a decade ago but if I remember correctly the blue flame you want to see in those boilers was 1800F. I remember it was insanely high heat. But by the time the exhaust reached the back of the boiler it would have cooled to about 300F when the boiler got to the point where the exhaust was leaving at about 500f it was time for a shutdown and cleaning which happened about every 1 to 2 cords or wood depending on the wood. For the 5 or 6 years I ran that boiler before moving I burned 4 cord of wood a year and cleaned it once in the middle of the winter and once in the spring or summer when the heating season was over.
Thanks DanNH i probilly be lucky too reach 1500 f with my home built unit, just adjusting too the temp rateing of all the different alumina content fire clay difference, after i bought two bags of red art clay i found out it is only good max at about 1800f but some of the other clays have more aluminum oxide or alumina, and are more in the medium fire clays.2500f too 3000f depending on the clay type and if posible alumina is added too raise the max temp rateing.? well you can buy the aluminam oxide by the 50# bag but nor sure how high the redart low fire clay can temp be raised by adding alumina or not.?
No idea about the clay mixes. But from what I remember 1800F was the upper limit if you get the flame right through the sight glass with the secondary draft control 1200F was the lower limit I seen to remember for the Tarm wood gasification but I don’t know just where those numbers came from they are just what I seem to remember for the range 1200 to 1800F. So the 1500F your considering would be smack in the middle of that range and a good burn.
I was thinking the same thing. I tried to find info. I didn’t get much. Off the top of my head, after 40%, the aluminium content doesn’t help. But I think it is actually aluminium silicate oxide that actually helps. I think it is part of fireplace ash, but it needs to be purified. to get the potassium and other things out. Apparently it is kind of a black art, because clays all have different properties and/or I am not looking in the right places.
Mr Google kindly provided some info.
http://www.cndoubleegret.com/news/Main_types_of_alumina_silicate_refractory_brick%20.html
Your google foo must be superior. 
Apparently you can make aluminium oxide from aluminium foil though. However, that is a lot of aluminium oxide to make for a firebrick.
