Rocket water heater

Hey this my first time posting in forum for anything so pretty much dont k now what im doing ..anyway.im building a 6 " j tube style massheater my burnchamber is in place . the total length of the burn chamber is 19 " ish.now i was thinking the riser needed to be 2\3 longer than the burn chamber .my burn chamber a little over 5 " square so does  that riser length include that 5" of burn chamber or does it matter ? I was figuring about 31.5 " riser - 2.5 because i have a row of brick down already so 29 1/4 ish from the TOP of the burn chamber sound right? Im also casting around a single wall 6" pipe with about 1" of refractory cement and chicken wire.then 1/2" copper tubing .then a column of redbrick and back filled with more refractory mix. 55 gal drum with 2" gap off the top of the riser.also was going to put the outlet on the barrel the same elivation as the top of the burn chamber .im sorta locked into that now .i know about not using metal in the riser but its just a form....that stays in .so i wanna know.what do the experts think???

Hi Jesse;  Big welcome to Permies ! And a big welcome to the wonderful world of rocket science!

You have some big plans afoot.  I'm not sure yet if they will work well (& safely) for you.
Let me see if I have this right.
Your building a 6" J tube.  Total length of the burn tunnel is 19" or so.
Is that including the feed tube and the start of the riser?  If so then your length is good.
Feed tube, burn tunnel  and riser are all 5.5" square?
Feed tube is how deep? 16" is common.

Ok , now your riser.  
32" would be fine although it never hurts to go longer.  You do measure from the top of the riser to the floor of the burn tunnel.
Lets step ahead a moment and I will say you would do better with a 3" or more top gap from the barrel lid.  I ran a 2.5" gap for years but it has been determined that unless you are cooking on the barrel lid you really don't need a tight gap.

Using a sacrificial metal pipe to line your riser will work but there could be an issue.  That metal is eventually going to fold in on itself. Partially blocking the riser.
I suggest using a round concrete form instead. It will burn out in the initial fire and your refractory will be left intact.

So now we come to your water making plans.  There are several very easy plans, to use a rmh to make hot water.   None of them use pipe around the riser.
As I read it you want 1" of refractory as a riser, then 1/2" copper pipe wound around.   After that you want to put red clay brick around the copper pipe and use more refractory to fill the void?
Then I think you want your copper pipe to pass thru the side of the barrel and go where ever you wanted hot water?

You haven't mentioned anything about your mass or your transition area to horizontal.  
Nor have you said how you are supplying water and where you are sending that water too?

Water in small pipes can flash to steam in a microsecond, the results are catastrophic!  

If your not already building we will happily tell you alternatives.
If you are building then be aware of the possible dangers.

Hey a reply! Haha yes the whole chamber is 19 total.this a heater for a galvinized water trough 8×3×3.the mass heat tubes are 6" and burried in clay with some sand on top under the tub .pipes go out about 12 feet and 180 back and 90 up next to the barrel.i havent built the feed tube yet .the water is coming off the bottom side of the tub on one side and the hot i was going to split and bring to each end of the tub around half way up im guessing.the whole burn chamber is fire brick and refractory mortar .at should have said 1" min. Around the riser before the copper the reason for the metal is one i have it and 2 i was going to use some screws just poked into the pipe to use the heads as a guide for the concrete also to hold some wire in probly end up with more like 1 1\2 of refractory around it .to make things even more interesting i plan on making a cob type pizza oven just over the top of the barrel and make a removable plug heavily insolated up into the rear corner of the oven directly over the rocket riser.the barrel has a removable top and im going to split the sides in half and make it bolt together so i can service if i need and also give me an easy place to run my copper lines through the barrel .

Ok so my feed tube is 10 1/4 from the floor of the chamber so far
The riser is about 8" from the floor to where im going to build the rest of the riser .so i should subtract that 8 " off my original plan ?? Also am i correct on that ratio of the riser being 2 /3 longer than the burnchamber ?

Ok so im kinda just moving forward  with 32" from the top of the riser to the floor of the burn chamber .i left the crimped edge of tje pipe up so i can add on if i need to .i poured concrete  around my burnchamber up to the level where the barrel needs to sit which happens to be a full hight barrel and a 3" gap from the lid..and all around the riser is at least 3 " gap.the one thing i didnt notice till now is the side of the barrel is basically going to be half of my feed tube for the top 6 " i have a 8" clay pipe with a bell end i might just cut the back off and mortar right to the barrel or maybe cheat the whole barel over a little off center?? Tilt the feed tube? Im also planning on some sort of sheet metal trough to angle into tje feed tube so i can gravity feed about 6 ' of barbie doll logs at a time .anybody do that??

Hi Jesse,   Could you provide some photos of your build so its a bit easier to see what your building? I'm a visual person  :) Thanks.

The barrel can be positioned off center without any problems as long as their is enough space for the gasses to make the transition from the barrel into the manifold or plenum.

It is generally not recommended to have any wood sticking out the feed tube as sometimes the fire starts to creep up the logs and can smoke back into the room. Worse case scenario, fire can burn up the logs and catch the house on fire!  A properly drafting rmh should never do this but sometimes things don't always work out exactly as we planned. Especially when we turn our backs to them.

I have no idea how to add photos

That's an easy one Jesse.
When you go to reply, click on the tab below the dialogue box that says "Attachments".
There you will see several buttons to indicate where your picture will be coming from: "Upload a File" is uploaded from your computer to permies.com or "Add from URL" which is already posted somewhere on the internet and links to it. However, a simpler way to link a photo is to go to right click on your photo, "copy image address" then press the "Img" button (above the dialogue box) and paste it. Click the button "Preview" below the dialogue box to see your picture displayed. Press "Submit" when your ready to post.

Hope this is clear. Write back if you need more help.

I just have a smart phone .I can get file selected but there nothing to get it on my reply when I hit submit it dosent do it

No file?

Ok Jesse;
From your picture I see what you need .  Your barrel needs to slide back towards the riser. Adding a row of bricks on each side will support the barrel.  Let the barrel hang out the back side.
This is where your horizontal transition area starts.  

Cast riser

Was thinking of something like this after I wrap the copper around the riser and backfill with more refractory or cob? Thinking cob now in case I need to take it apart.would it not be a good thing to fire it up if the cob is still wet? I don't think cracks would hurt really since its more of an insolation barrier for the copper .ill Probly mortar the bricks and back fill with cob.idk I keep going back and forth .

Thinking about using the clay pipe as the feed tube.does it matter how tall it is .16" pretty normal but does it matter if its longer ?

Hi Jess;
Yes , length matters. If you lengthen the feed tube you must also lengthen the riser.
If you don't, then the fire could switch directions and treat the feed tube as its chimney... not pretty.

Doing it

So im having some issues with draw i think.i was playing atound with different size pieces of wood and different kinds of wood .also the angle of the pieces when theyre in seems they do better when i lean the bottom in more .im getting a greyish cold vapor out of the stack on the end.it seems to do well at first then coals build up and it starts puffing back and burning up the feed tube untill i stir it up .sort of a disappointing amount of heat but i think its because its just not woofing like it should building up coals faster than it can burn them down..i can feel the copper get hot and work its way to the tub but just before it gets there it stops burning as well and the copper starts cooling off again away from the tub .i do have a 6" inline fan i may put on the end of the exhaust to help pull everything through just as a temp way to figure out if thats my problem before i start changing the barrel around.also at first i had maybe a 5 " gap from the top of the riser to the lid and then temp raised it to about 3" maybe ill take it back down to 5.any thoughts? I was hoping the stove would heat the water too quickly if anything like people here and other places have mentioned before abut it flashing to steam but its nowhere near getting that hot

I thi k i need a bigger barrel haha

Hi Jesse;  
You need a smaller riser not a bigger barrel.  A nice 5 minute riser would outperform yours with half the size.
With you mentioning the thick grey cloud...out your stack.
Your system is still wet. Until it dries (can take weeks) you will not get a hot fire nor good draw.
And you won't get much hot water.
EDIT)  I was just looking at your pictures.  It appears that you have no transition area?   Looks like you just have a horizontal pipe inserted in the barrel?
If that is so then that is your problem area.

Yes Thomas .its just a horizontal pipe sealed into the bottom .what is a typical transition ?? I know the riser is fat but that Is as tight as i could get it with the 1" pipe , copper coil,and brick.my thought was to get to get some mass around it and see if it stays hotter longer .idk it was just an experiment with what i had .any advice is greatly appreciated im not really up to par on most the terms and ill be getting a book now I have seen all kinds of little homemade water heaters similar but small and metal im just trying to build a better version of the you  tube junk and if it heats the clay under the tub too that is a bonus .i can fab anything on the barrel to gain more gap around the side .i sorta got the blueprint on line for the stove that made the most sense to me but just showed the the horizontal tying to the barrel like mine .ill research some more

Hey Jesse;
The transition area is where you convince the exhaust that it needs to escape down the horizontal pipe.
You accomplish this  by funneling that heat into that little bitty six inch pipe.
At the very least use an 8" to 6" adapter to encourage that cold smoke to travel into your mass.
Or build your own with sheetmetal and make it 10" into 6".
Bigger is better.
And I'll reiterate the mass must be completely dry before this thing will rocket.

I tried posting several pics but they never want to go through

Jess; It may be that your pictures are to large .
I had problems here posting after I got a new camera.
Turned out the resolution was set very high.
As soon as I lowered that down  I could post as many pictures as I liked.

Ok thanks .i might just have to ditch the mass tubes all together in that case they are buried under the tub in the ground which is pretty much 100% clay and never drys .ill come up with abetter transition what you were saying is exactly what i was thinking when you mentioned  it .is it just the moisture that makes the air heavier to flow ?theres alot of moisture i can see in the barrel too it makes sense .thanks

This all  cheap smart phone and bad connection

I guess 4:00 am is the only time i can post a pic.everytime i try it just goes to a page no longer available thing then loses everything i wrote .whatever, i hooked the inline duct fan to the end of my exhaust and Wwoooof!! It rockets and nothing but clear heat waves coming out som im going to run it like this while work on other stuff like plumbing and let it dry.i think i will forever have moisture in my mass because its outdoor so the fan may be forever. As for the water it gets really hot and it does convect into the tub but nothing is insolated yet and im losing heat because im so far away from it so im going to install a inline circulation pump on the cold line inbetween the rmh and the tub.my goal was to heat this tub in 2 hrs with no power but its right inbetween my outdoor bar and the shop i got power ran all over out here .ill try and get some pics of it going later .my only concern is it maybe working too well and too hot i think the reality is its working like it should be

Fan crapped out.i knew it wouldnt last long cause its an old one i use to use to suck fumes away while welding galv metal.and im thinking now the clay and brick i encapsulated the copper coil with ( trying to create a mass that would stay hot and even ) is actually blocking heat from the all the heat from the barrel from heating the copper as well. If i take the clay and brick off i will also have a smaller riser to help with my draw issue .since ill have to pull the barrel to make a better horizontal transition anyway ill do it then and im glad i used more of a cob mix instead of mortar. Another thing i noticed is inbetween feeding the fire the heat slows big time and the still cold water from the tub starts feeding back into the outlet since it is submerged .might elbow up and out so it wont back feed cause once it cools off it takes forever to heat again .mainly just not hot enough even pumping water through the coil slowly .as far as the stove it works well with a few mods it should work great! I might just use it as a heat source for a pizza oven and build another set up closer to the tub if all fails .also i will do a bigger system