Playing around with rockets

[louisbiker]

I've decided to build two rocket stoves. The first will be a Rocket Mass Heater for the house. Situated in the garage, boxed in with sheet metal and ducted into the house.
The second will be a BBQ for outside.

To get a feel for the process and see how these things burn i thought i'd whip one up.. just the rocket heat riser. no drum.

Grabbed some pipe that was lying around and welded it up. just guessed the length of the burn tube and riser.



Got pretty hot. maxed out my non-contact thermometer. so way over 350 degrees C. (660F)

I ordered some vermiculite fire bricks and used some heat-proof tape i had lying around to try and insulate the burn tube and the heat riser.
Also added some little doors one on top of the feed tube to control the amount of air and one bottom of the feed tube to facilitate cleaning.



It got very hot (on the top of the burn tube) and I realised that this pipe is galvanised and it would probably start putting off zinc chloride (i think) or something nasty. lucky it was outside and a little breezy. though not good stuff. I'm going to grind it off.

The thermocouple on my multimeter got to 670 Degrees C. (1238F)

I was very impressed with how hot it can burn. with proper insulation and dry wood it would scream. I got some weird noises out of it. started to sing a little.

Anyway. my first tests of rocket stoves and can see lots of potential, should be able to heat the house easily.

If anyone can see any glaring mistakes i'd love to hear. (apart from the galvanised pipe )

[Nutcase]

Neat! I'd make something like that if I had the material and the welding setup. How long does it take to stop smoking? You could insulate it by just sticking it into a box filled with vermiculite or perlite, I wonder how that would work. Fortunately, zinc isn't a cumulative poison. Lots of info on "foundry flu" online, putting the potential risks in perspective. For an outdoor cooking setup with no heat capture, I'm not sure you even need to insulate the chimney. A barrel would just be there to diffuse/redirect the waste heat flow so that it's not in your face while messing with the food. Lots of ways to mod a barrel if it doesn't draw well.

Nice looking gravel path.

[matt walker]

Welcome Louis! My first experiment looked a lot like that, they do sing, don't they? That's a great little test rocket you built, but one thing to know is that you will have to get away from the metal for any stove that you want to last. Even that heavy wall section will not last long in the burn works. The bricks you have, on the other hand, will be perfect to build a combustion chamber with.

I'm excited to hear that you will be building a BBQ. I'm absolutely convinced that these things make the best outdoor cookers available, and not too many folks are aware of their versatility. Have you seen my smoker video? It shows my technique for controlling the heat from the rocket. I'm so pleased with that set up, I believe there is a lot of potential there. If you do go that way, an insulated riser is mandatory. Your bricks will be great for that as well, although there are lots of ways to get there. Glad to have you here!

[louisbiker]

Thanks for the replies Nutcase and Matt.

It would only smoke if I started to shove too much wood in or when I was starting the fire. It's amazing how quickly it will burn cleanly.

Matt, I can imagine that the steel tube will be under a lot of stress especially when insulated. i think it was glowing red when i had it at it's hottest.
I'll have a look at your smoker video.

I'll make some changes and post some results soon.

[Nutcase]

[louisbiker]

Nutcase, I was measuring just on top of the burn tunnel about half way along. Probably the hottest point. I wanted to see it will get hot enough to melt the steel.

I think the steel being that hot will oxidise very quickly.