RMH Calcifer info and issues

I wanted to repost this with updated information and to clear out the chatter as well as as focus on newer issues I'll start with current info and then move on the issues

Calcifer weighs in at about three tons with a 13 and a half foot Bell about 2 ft tall the walls of it are 3 in solid cinder block half blocks with two inches of concrete on the top and bottom the inside diameter is about 12 or 13 in ID the OD is closer to 20  
It runs on a small batch box with a 6in exhaust when running good and hot the barrel reaches temperatures have anywhere from 650 to 800 Degrees  above the riser and the outside Stone around the core reaches about 135 to 140 degrees and the benches are anywhere from 100 to 120 degrees though they take a while to warm up. Ambient outdoor temperatures in the twenties this will keep my house above 55 degrees for at least 12 hours.

At first I was having issues with backflow and cracking fire brick however the cracking seems to have solved itself and the backflow was fixed with a assist fan

My current issue now is soot I'm getting a crap ton of soot build-up on my exhaust fan which i imagine means I'm getting it all throughout the system I don't believe there's any creosote buildup or anything of that nature as I attempted to light some of this on fire just to see how flammable it is and it seems to be fairly resistant even to a 2000 agree torch so I don't believe it poses a fire hazard but it can't be good for that much buildup in my system. Unfortunately my infrared heat tester maxes out at a thousand degrees so it's hard to say how hot the burn chamber is but I'm pretty sure I'm getting the 1200 degree minimum

Also please note I'm still in the process of building a proper door for the fire chamber and I have yet to add a concrete countertop across the top of the entire thing the idea is for the barrel to act as a cooktop built into my kitchen countertop

I can't say for certain without seeing a burn (and listening) in person, but my hunch is that you might not have enough turbulence in the burn chamber to mix all the exhaust gases with incoming air for complete combustion. Your firebox is basically a box, right? In the photo it looks like a big L-tube and although it's a very free-flowing design, it doesn't create a venturi in the same way a J-tube would, nor does it have the secondary air channel of Peter's batch box design. So, even though you're getting sufficient temperature, it's not getting the mixing effect.

Phil Stevens wrote:I can't say for certain without seeing a burn (and listening) in person, but my hunch is that you might not have enough turbulence in the burn chamber to mix all the exhaust gases with incoming air for complete combustion. Your firebox is basically a box, right? In the photo it looks like a big L-tube and although it's a very free-flowing design, it doesn't create a venturi in the same way a J-tube would, nor does it have the secondary air channel of Peter's batch box design. So, even though you're getting sufficient temperature, it's not getting the mixing effect.

I thought that was the purpose of the barrel 2 mix and cause turbulence  but you're right I do not have that bottlenecking Venturi effect .i spent a year watching videos on these things I never realized that part was there let alone important lol  mine is also a 6 inch Riser with a 6in exhaust its 6 in all the way through

When you say secondary air channel do you mean air inlets into the Firebox for extra oxygen? Because I do have one on either side of the box if that's what you're referring to

Any suggestions? Currently waiting on mortar to dry but I'll have a more proper door here shortly my primary concern right now is reducing the soot

So I just had an idea the bottom of the L of my burn chamber is excessively long what if I bottlenecked it to a 4in Venturi chamber feeding into my current six inch riser it would be a short chamber Maybe two or three inches but it would bottleneck it and it would be at an upward angle problem is if I do this it's unlikely I'll be able to undo it if it doesn't work
Another idea is my Riser is excessively tall at 17 in I could sacrifice a few inches of my Riser & bottleneck the base of it to a 4-inch that might be easier to remove if it doesn't work perhaps that way create a sufficient Venturi effect how long does that bottleneck need to be to properly mix and burn up the soot?

Got my door instaled  

Is that a casserole dish lid? If so, it does look nice but do be warned that quite a few people that have used them have commented that they either crack or shatter under the intense heat/cooling they experience. Casserole door In particular, Matt Walkers comment about a 1/4 of the way down.

Gerry Parent wrote:Is that a casserole dish lid? If so, it does look nice but do be warned that quite a few people that have used them have commented that they either crack or shatter under the intense heat/cooling they experience. Casserole door In particular, Matt Walkers comment about a 1/4 of the way down.

I have a fan on the back side of it to keep it cool it was an extra if it blows up whatever I'll try something else however putting that little steel bolt through it as a handle works great as the steel bolt stays cool don't need a oven mitt to pick it up but mine is currently at about 500 Degrees and I know that's pushing it but we will see

Hi Ryan - A picture is worth 10e3 words, and a movie, etc....Take a look at these videos:

This is Satamax showing the dual ram's horns in a batch box system where it goes from burn chamber aperture to riser

Another batch setup (don't know if this guy is on permies)

You can get the feel for the velocity and mixing ability of those gas streams just by seeing the clips. That is the crucial puzzle piece that I suspect Calcifer needs to stir him from his torpor. (Love the name, btw...I've lost count of how many times we watched HMC.)

Calcifer?
Miyazaki FTW!
I curious about your exhaust fan.
A batch box is tuned to work off of the natural draft created by a proper chimney that matches  system diameter.
If you are using a flue that is sized to match your system,  a powered fan might be cooling your burn by introducing too much combustion air.
An unpowered fan might be slowing down draft,  but that seems unlikely.

Thank you for the videos  
Im thinking my riser is longer then it needs to be so im wondering if i can bottle neck it at the first 2 or 3 inches of the base of the riser with castable fire brick  i have a 6 inch riser not sure how much to reduce it at the base 3 or 4 inches? My batch box is rather small

For the moment the fan is a must as it stops backflow. I just slaped a pc fan on it lol its goofy but works wonders till i can figure out a more solid fix "witch might be the same fix as the soot problem

Have a close look at the evolved and tested design of Peter van den Berg's batch box. The secondary air channel and port are critical to success in this breed of RMH. Just putting in a restriction may give you even more draft issues.

Phil Stevens wrote:Have a close look at the evolved and tested design of Peter van den Berg's batch box. The secondary air channel and port are critical to success in this breed of RMH. Just putting in a restriction may give you even more draft issues.

Where can I find this newer batch box design

If you need to use a fan then the draft isn't correct which may mean not enough oxygen is getting to the fire.
Soot burns at over 1112 deg F but you will deposit soot at the beginning of the fire along the exhaust path, and surely it will remain there as those temperatures are only reached in the burn chamber and riser.

Is the system smoking outside at all during the burn as opposed to just the beginning?

My 5 minute riser deposits soot as the fire starts up but as the fire gets going the soot burns off again.

Yes that was another concern of mine I am still getting quite a bit of smoke out of the exhaust which makes me wonder if I'm reaching the proper temperatures however my heat gun maxes out at 900 to 1000 degrees and it Max is it out every time quite easily and my Barrel has reached temperatures upwards of 800 so I find it hard to believe that I'm not reaching high enough temperature but the fact that I have smoke makes me doubt that I am

On another note I finished my bottleneck and it does seem to be adding to the rocket effect which seems to be solving the backflow problem I was having as I'm now able to turn off the fan once hot no it does not seem to have done anything for my soot or smoke issues
I bottlenecked my six inch riser with a bit of castable fire brick around a 3 in cardboard tube which is the center of a commercial roll of toilet paper LOL