Decided to build my first stove

ievolve wrote:

 Perhaps it is just my design, but when I start it up from a cold start I can expect about 3 or 4 mins of massive amounts of smoke (as any fire would), if this thing were in my shop I would be all smoked out by the time things were rolling.

Every stove smokes at the beginning while the all "burning system" is cold. You're talking about smoke that raises from the riser tube or the feed tube?

ievolve wrote:

Yesterday I added a mesh screen to hold the coals off the bottom of the burn chamber and allow air to flow freely under.  It seemed to make a pretty big difference for my stove, I had much better airflow, it burned hotter, and seemed like I had better re-burn in the heat riser too.

Nice. This was an observation  that I think that I saw in my stoves, but now you confirm it.

ievolve wrote:

One other curious point is that during a burn, I can cover one of the barrels and it will increase flow in the open riser.  The flow increase is to be expected.  But what is odd is that according to my math, covering one of those risers should create a choke point, but it does not.  Has me wondering if I can get away with smaller openings into my risers and perhaps create more of a venturi?

I am not sure. Without measuring flows, temperature outputs and combustion product composition it is hard to confirm your observation. Actually, I do not think venturi effect is relevant here. In your case, the open raiser is still more than enough to allow good flow of air and gases.

ievolve wrote:

There are a couple things I will be trying this weekend.  

First is I want to insulate my heat risers pretty significantly and see what side effect (if any) I get.  

Personally, for the case of rocket heater, I do not think we need insulation in the raiser tube. The raiser tube is already inside a very hot environment. Probably insulation of the raiser tube in a heater allows you to get very small gains in heat output. On the contrary, for a rocket stove cooker, you need insulation to achieve maximum temperature at the pot.  

ievolve wrote:

Second is I want to try a different secondary air strategy, I just dont feel like my secondary air is doing much of anything, whether I cover it or leave it open it really doesnt make any difference in the heat riser.  Have any of you seen dramatic differences in your heat risers when you open/close the secondary air?

Visually, you will see nothing. Pekka, showed in one of his Youtube videos a dramatic increase in temperature output when he opens secondary air intake. You can make one test by firing your stove with the secondary air closed and when the stove is hot, open the secondary air. You most certainly will notice that the residual smell of smoke that you may feel, will disappear...

By the way did you change anything in your secondary air intake?

@catropheous thank you for the feedback. I've yet to change anything on the secondary intake, but that is where my next round of tests will focus.

I am semi frustrated that I dont have any equipment other than my eyes and nose to tell me more about how things are performing. I am exploring building some electronics to be a more accurate judge of what is going on.

FYI I did insulate the heat risers in this last burn I did yesterday and it did not appear to effect the draft at all. In fact it had little impact at all for me. I think you are correct, in a heater this maybe isnt such a big deal.

were is the finished stove today 12-14-2014..
lol date shows next month
Fri Jan 03, 2014 1:35 am