Bricks for the box of my cob bench

Do we really need another one at the foot of the vertical pipe going out the roof

for the dead birds

I only have one clean out but it gives me direct access to my manifold and the first 11' of horizontal piping, the other 9' of pipe I would use air to blow up and out. In the case of a dead bird I would open up the exposed vertical pipe to gain access to dinner... lol, your making me laugh shilo.

Thomas: you mean your ducts are at different sizes? 11 at first and then smaller to 9" ? What benefit would that give?

No Bacon; My duct work is all 8" , I was referring to the length of my horizontal piping , 11' down to the 180 degree turn then 9' back to the 90 degree turn that comes up out of my mass.

My goodness, I only cleaned half of the bricks, the refractory cement bond good. Many bricks got chips (most of them). As this is not for the heat riser. For burn tunnel and the bottom of the heat riser, the 90 turn up to heat riser, is ok if the bricks are chips here and there. Should I use mortar (fireclay and sand) and fixed the bricks or just leave them as they are (The feed tube I know it shouldn't matter. I am just wonder about burn tunnel and the 90 turn at bottom of heat riser, is it ok if the bricks got chips here and there

I cleaned up all the bricks. Someone told me Homedepot can cut bricks for us, I brought them there and they did. Tomorrow I can build the burn chamber, but the floor have not yet dried. Why it took so long, 3 days already. Maybe because I always have my greenhouse closed to retain the heat. Here is the pic of my floor protection. I will put some bricks to support it. If it's still wet, can I start the burn chamber or wait? Why it took so long to dry?

If homedepot cut the bricks for us, then I will make my heat riser by firebricks too. I will have only one clean out at the transition. I can't have dead bird because I have a witch hat on top of my smoke pipe. The pocket rocket heater is a very big job for me too, and I am scare burning that in my little back yard. However, I found a shop who will do the sandblast for me, good.

Why it took so long to dry?

because the perlite.
use a fan

I will do the burn chamber this morning.

Thomas: What is the high of your feed tube? The photo of your burn chamber (photo #43), is it 4 bricks high (on width) ? I do calculation, and you have 3" floor protection, 2.5" base for burn chamber, 4.5" for first layer (all through layer), 4.5 for layer with burn tunnel seperates heat riser and the burn chamber. So total should be 3+2.5+4.5+4.5 = 14.5, right? How come on your photo #52, look like you your feed tube was up to the high of 4 bricks (on edge) which is 18" ? So, did you add another layer on top of photo # 43

Thomas: Also on photo #12, I noticed you don't have a wall of bricks to support below the barrel where it open into the transition. Did you put a wall of bricks on later or you leave it like that? I will do my this morning, and i want to do mine like your to make sure I am ok. Don't want a redo again.

Good Morning Bacon; My feed tube is 16" tall ,3 bricks on edge sitting on top of one laid flat. As far as the back of the barrel , No I do not have a wall at the back supporting it. There is plenty of support from the front & sides. The back is open for easy flow of the heat down into the manifold. I laid hardware cloth from the barrel over to the rock that covers my manifold and cobbed it over thickly to seal it off. And before you ask my riser is 45" from the floor to the top.

I manage to have it done up to here. I have to wait for more bricks to cut. Homedepot didn't want to cut bricks for me today. It seems like depend on the person if he/she want to do it or not. Home Depot doesn't have it as a service, too bad. I have to try again tomorrow for my luck. Hopefully I got a person who would want to help. I have question please

I think I will do my heat riser in full size firebricks. When I break down the old one, I notice the split is very easy to break. The full size is very hard to break. I don't want my hard work break down soon someday. So I think my heat riser will be in full size firebricks

My feed tube, burn tunnel, and heat riser are all 5.25 * 5.25, awesome huh!

First, I put the lid of the barrel down on the floor protection and trace it with include some opening for the manifold, and then I build my burn chamber.
Please see if I did it right or if you see anything need to fix. Also, I have questions please

1) When I have bricks cut and finish with my heat rise and after it dry off (a day), I will do insulation. Can I do insulation and then cob them all level up at the same time, or I have to wait a day until the insulation dry off to cob it?

2) My floor protection somehow wassn't level. This morning I have to put a lot of mortar to level them (Mortar is 1 clay and 3 sand), is it ok? Mortar and cob are the same thing, right? 1 clay and 3 sand

Do we have to sanblast outside? The shop said that they sandblast inside only. Is it ok?

Looks good bacon; About your barrel ... all the paint must go, outside of the barrel is more important than the inside. If the outside has paint then it will burn off inside your house ! That is not acceptable. If there is paint inside the barrel it will go up your chimney and outside your house ... not nice to the neighbors but it won't hurt them.

Thomas and all: Can I insulate it and then cob it at the same time (fill the whole burn chamber up to the flat level for the barrel to sit on) at the same time or I have to wait until the insulate dry off and then cob it?

Bacon Lee wrote:
Do we have to sanblast outside? The shop said that they sandblast inside only. Is it ok?

I think they must have understood that you wanted them to do the work outside! I can't see no other reason, exept if they have no cabin, but that's not a sandblasting business then!

Bacon; I don't understand, what are you using for insulation ? I'm guessing that you can cob right away.

Thomas, are you sure that I don't have to insulate the burn chamber? I remember Glen, and Eric, and Allen has talked about insulated it. They said in this post that we have to insulate it to keep the heat inside the burn chamber, that's the main point of rocket heat, right? Or I misunderstood them?

Satamax, they are not the sandblast business. They are a autobody shop. They have sandblast machine, and I ask them to sandblast for me. But now they agreed to do the outside as well, but I have to pay them $20 extra. So, it cost me the total of $100 to have the barrel sandblast. Mine, I remember someone on youtube said the rocket mass heater cost total around $200. Now I do it, it cost me a lot already. But I can't stop now. So I will not eat for the next many month. Or I only eat vegetable from my aquaponics.

Yes insulate, then cob

No one gives me tips, so now I will give you tips:

1) When we build heat riser with bricks, beside make sure it level, also we should measure often to make sure our measurements stay the same. In my case, when I finish build my heat riser today, I measure the top layer, surprised! I suppose to have 5.25 * 5.25, it turn out I have 4.75. How could this be, I don't understand it, but that was what I had. I had to undo the whole thing, and clean up to reclaim the bricks again. Good thing this time the glue didn't dry yet, so I have the hose spay them hard. That's it for the day. I am tired and had nothing done. Tomorrow will continue

2) In case you need to cut bricks and don't have tool or don't know how to use tools, this is what you do: Draw line on brick where you want to cut, get a hatchet and hammer to pounce a long the line to mark down a little. Then stick it in the Smart Splitter, it will cut, not a smooth cut line like with the saw but, it does break the brick at the line. In case you don't have a Smart Splitter yet, then that's the only thing I recommend you to own. Split wood awseome. That's the best wood splitter ever:

https://www.youtube.com/watch?v=74mlHNA6i20

Do you have any tips please tell me. i don't want to make mistake and redo again. It's awful

Bacon Lee wrote:
"No one gives me tips"

What?? This entire thread has been *almost* *entirely* people giving you tips!

But others cannot tell you everything. Yes, you build level. Yes, you should check this regularly. Yes, you should check that square are truly square.

How does 5.25 become 4.75? By not measuring accurately at each course.

The other side of this, is this is obviously one of your very first building projects. Most people offering advise have long ago gone through these kinds of "learning curses." Everyone goes through this kind of thing. It's called learning your trade. Even if that "trade" is only for home-building. It still requires we make mistakes as we learn. One just hopes to take extra caution and study when dealing with fire, electricity, and structural elements.

In other words, you are "paying your dues" as the saying goes. You are going to make mistakes. You can diminish these by reading and study and asking advice. But you will still make them. It's just how most of us learn.

I didn't know it's hard to keep the measurement the same. Today too, I have to continuously fixing it so maintain it as 5.25.

Now I have a very bulky heat riser (diagonal 14"), and diameter of my barrel is only 22.5. Am I having problem here? I think it is appropriate to insulate with rock-wool, but they have a very big bag, almost the size of the twin bed. We have to buy the whole thing, they don't have smaller bag. My guess I just need about 20% of that. I don't know what to do with the rest. If I use perlite, I am afraid I may knock off my heat riser. What should I do now? Can I do perlite with out the outter protection? I just stack perlite on the heat riser?

You can wrap the rockwool around the riser and cage it with chicken wire or any other wire mesh. It's okay to have a somewhat thinner layer of insulation at the corners, as they already get less heat than the straight sides of the riser. You can't get pure perlite to stay in place around the riser, but you can use any kind of sheetmetal (not aluminum) wrapper to hold it. You can also mix perlite with just enough thin clay slip to make it hold together and form that around the riser. When it dries it will be rigid. A few wires or mesh will make it more secure.

Bacon Lee wrote:
I didn't know it's hard to keep the measurement the same. Today too, I have to continuously fixing it so maintain it as 5.25.

Now I have a very bulky heat riser (diagonal 14"), and diameter of my barrel is only 22.5. Am I having problem here? I think it is appropriate to insulate with rock-wool, but they have a very big bag, almost the size of the twin bed. We have to buy the whole thing, they don't have smaller bag. My guess I just need about 20% of that. I don't know what to do with the rest. If I use perlite, I am afraid I may knock off my heat riser. What should I do now? Can I do perlite with out the outter protection? I just stack perlite on the heat riser?

22.5 - 14 = 8.5
8.5 / 2 = 4.25 inches on each side, where 1.5 is a bare minimum (and more is better) gap between the fire riser and the barrel. I'd probably try to size the containment for the riser to be about 1-inch or so beyond the corners (diagonal) of the brick in the fire riser. If you recall the previous discussion, you can get several pieces of the ductwork, and pin them one to the next, and make a larger diameter tube to hold the perlite & clay mix.

Filling a metal tube with perlite clay mixture would be the easiest way of insulating (assuming you do not buy the rockwool - wrapping it with rockwool is the easiest, you only need to tie it in a few places with bailing wire or something like that.

Alternately, you could paint the brick with clay, and then just start "cobbing it on" the brick. Then after you get it build up several inches thick, you could wrap it with hardware wire (1/4" or 1/2") or even chicken wire, I suppose, and put on the "final coat" with a greater percentage of clay, so it goes on more smoothly and serves as a final coat, holding the rest in.

So there are a number of options.

If you like the idea of using rockwool, I'd call all the hardware stores in your area. I would be surprised if rockwool wasn't available in smaller packages.

I think I will go with the option Glen said, to mix just enough clay with perlite and form that around the heat riser. When they dry, I will wrap around with wire mess

Erik: The 14 inches is before 2" insulation . But now I will make perlite insulation in a way which will not increase the diameter of the heat riser/insulation. Which mean not much at the corner as Glen said, the perlite will curve around where straight edge around 2 inches, and at corner, not much, right?

So, my side gap is not so loose. if I push my heat rise toward the back of the barrel where the feed tube is so I can have more room in the front for the transition to the flue, is it ok ? (I mean my heat riser will not be at the center of the barrel)

Erik, We only have Homedepot and Lowes, I already went to both stores. No, no other size, the have a twin bed size, and that's it!

The fire riser does not need to be dead center. Closer to center is ideal, but not a requirement.

Glen: You mean I have an option to use perlite alone dry and don't have to mix it with clay and water? If this is the case, I can do it. I am afraid of putting the slip of clay and perlite into the slot of heat riser and duct, because I have to press the mixture down, I am afraid I knock off my heat riser. If we can use perlite-DRY-alone, then I can do it. I will have duct 14 inches diameter, so the corner will not have insulation. Around the straight edge, I will pour perlite in there, good deal?

Awesome, then I will have my heat riser off-center to give me room in the front.

I decided to buy the Roxul. I use whatever I need and the rest I will give it to an accquaintant who is a construction. He remodel houses, he may need this. I think it the easiest thing for me. The metal duct will be a little work and I am sure I can do it. Good idea, huh!

Rockwool is good for a number of uses. For example where your chimney pipe goes through the roof, you'll most likely want a 2" air gap around the pipe (and your code may require it) but some codes also state that a 4 to 6 inch gap/distance must be maintained between the chimney pipe to combustible insulation, like cellulose for example, but you could use the rockwool to insulate that 4 to 6 inches. It may also be used to help insulate clean out covers, or as filling in expansion gaps which also have to withstand high heat. Etc. I'd keep it around until you are finished with your project. It is a handy and easy to use insulation, especially when building a wood burning heater.

Then I definitely need to buy that roxul. Right now I have my pipe snug fit through that plastic roof (1/4 slot). I will make it 2-3" space and put this rockul around it. Also, you are right Erik, I can use some more to wrap around those 4*4 woods on the top of the barrel. I have more safety device.

Also, I think I will add another layer of brick on my heat riser. Because I want to cob level to the feed tube, which is 3 layers, then I have 6 layers left = 27 inches. My barrel is 33 inches. If I have another layer, it will be 31.5 inches, and I will cob above the 3 layer about an inche, then my top area is around 2.5". That's just right, huh!

Bacon, carefull with too tight a heat riser gap. Better to have it too large, exept if you plan cooking a lot on it. So i wouldn't add another course of bricks myself.

I too would leave the riser as it is. This is in a greenhouse, so I doubt you need or really want to cook on top of it.
Besides, many build up a sloped on the top of the last course out of fire clay and a little perlite (just guessing here, maybe twice as much clay as used to insulate the fire riser?) so the fly ash tends to fall off the top of the riser, and not accumulate there.
That angle can be an inch or two tall. You can slope it either toward the inside or the outside. You may recall Ernie Wisner saying in one of his videos he prefers sloping it back toward the center, to try to get the fly ash to fall back down the fire riser, where he can remove it with the ashes from the burn.

Bacon Lee : The Heat Riser should be dead center. The barrel over the top of the the Heat Riser can be slightly off center ! This will generally create a Cooler
and a Warmer side, with the pinched or narrow side being cooler !

The gap between the top of the Heat Riser and the Bottom of the Barrel should not be smaller than 1.5 inches with a 6'' System, 2'' with the 8'' System.

You can experiment with a larger Heat Riser / Barrel gap, this generally moves the hottest spot on the barrel from the flat top to the sides of the barrel-

Some people have reported that with a gap exceeding 3'' that the cool side and hot sides of a off-set barrel are reversed, the latter is is not something I have
experimented with !

For the Good of the craft ! Big AL

You can slope it either toward the inside or the outside

toward the inside is better to the stream profile

Ok, thank you all for your advises. I will not add another layer then.

I already done with insulate the burn chamber. This is hard, because we want only 2 inches of perlite/clay. If we fill all the way to the brick-wall then it is easier. What I did was, I made a wall around the burn chamber with 2” gap, so I can stuff the perlite/clay into the gap. I used cardboard, wood-board, dart-board, I even had to borrow Ensure boxes from my mom to make wall around the burn chamber.

After I did the insulation, I measured 30.5” from the platform of the insulation to the top of the heat riser. Which means if I put the barrel over it, I will have 2.5” gap. I plan to heat water in copper coil on the lid for my pond of Tilapia. Is 2.5” good ?

I had to give up on ash-pit and transition like Thomas did. I want to do it like that, but I have to accept the fact that I am just a lousy woman. I don’t know how to do transition area like that. I will worrry a lot that my systerm/barrel collapse with a hollow area below the barrel if I don’t know how to do it properly. I rather have everything around the barrel solid. So, I will go for the register boot. I go for this one, open up from bottom:

http://www.ebay.com/itm/like/161562842091?lpid=82&chn=ps

I had to give up on the angel lip too. This is too luxury of a lousy woman who is tired already.

Tomorrow I will take out the wall around the burn chamber and cob it included a register boot. I will insulate the heat riser and then ready for test burn when my barrel is back from the autobody-shop.

Allen: About the barrel, that's what I mean. When I put the barrel over the heat riser, instead of aiming for the heat riser to be in the middle, I will move the barrel forward a little, which means the heat riser closer to back side of the barrel and leave more room in the front. It is ok, right? Please let me know because I will include the register boot in tomorrow assuming that I have more room in the front

Please think of any tip to give me before I do it tomorrow. I am afraid of a redo. /Just want to make sure I got it right

I have the locking ring for my barrel. So I put it on the heat riser to take picture so you will know what I am talking about. I just want to make sure before I do it tomorrow of include the register boot in the front with the assumpsion that I have more room in the front. Here are the pictures:

I use the locking ring (the metal ring) as though it is a barrel. In the first picture, I aimed for the heat riser in the middle so the front side where Ensure box is and back side where feed tube is, are having the same side. Then in the second picture, I move the locking ring toward the front, so now the front where the Ensure box is, I have more room. The back side where the feed tube is smaller.

That, Am I ok doing that?

When are you going to insulate the fire riser?
The fire riser insulation is supposed to go up the entire height of the fire riser, not just the bottom few courses.
However you do it, that needs to be done before you put the barrel over the riser.