Frank Johnson

Fist thing that caught my eye was the fact I did not see an insulated Core. I use 6" cast iron pipe 2" cob and the outer sheath of my core is aluminum 10" duct pipe. The insulated Core allows the retention of heat that helps the secondary burn of all the wood gas within the riser core, which creates massive amounts of heat.

The second thing that I noticed is wow that is a really long duct. I would imagine it will take a good long time to heat(charge the system) before it will start to draw the way it is supposed to. You may even need to set up some kind of forced air flow(bellows) to get the air started through that much ducting. Possibly a longer riser might help also.

Destiny Hagest wrote:I'm not sure which videos or books you've read on the subject, but there are a lot of great learning resources out there that you can just soak in to help you get through this project - I find the more I understand something, the easier time I have working on it.

Ernie and Erica just released their Rocket Mass Heater Builder's Guide, and Paul's brand new DVD set, Better Wood Heat: DIY Rocket Mass Heaters is also now available for preorder. That one's kind of nice, because it shows you both a cob and pebble style, and also goes into the inner workings of the core of the RMH a bit more.

Thanks for the links and info. I am familiar with Ernie and Erica and Paul's info. I have viewed maybe 200 videos about rocket mass heaters from all over the internet before building mine.

I will say that mixing mud by hand was allot harder than I thought it would be and when the time comes time to build the bench I will use a cement mixer.

Rob Sigg wrote:I recently built a small scale trompe, here are the specs:

Closed system using a bucket of water being pumped to the top of the inlet and then returning to the bucket. Im doing this only to test out the dynamics of it, this will be used on a natural water way.

3/4 inch inlet with one straw for air introduction, this is about 8 feet tall
transition to 1 1/2 transfer pipe then to a vertical 3" air entrapment with 1/4 air compression gauge and valve. The air chamber is about 2 feet tall.
The outlet part of the transfer pipe then goes to 1 ". The outlet pipe is about 5 feet tall. I experimented with a one way valve to try and create back pressure. Youtube Mr. Teslonians  Trompe Hammer for the gist of this.


No matter what I do I cannot seem to generate more than 1 PSI and of course once the pressure is releases the water level comes up and spills out of the top. I want to test this on actual falling water because I think it has to do with the volume of water going into the inlet pipe, it doesn't seem to be enough since im pumping through a 1/2 tube into a 3/4 inlet pipe.


If anyone has any further ideas/thoughts I would appreciate it and I can post more details if desired. I tried to contact Mr. Telonian but I can't find his contact info anywhere, he would certainly know the answer.

Sea level air pressure is 14.7 (1 atmosphere) psi. For every 33 feet of water depth that pressure will increase by 14.7 psi. At 99 feet under the surface of the sea you will increase your air pressure by to 4 atmospheres , which will be 58.8 psi. These calculations are what you would get at sea level, I am sure the calculations will change a bit at diff elevations. I think for a trompe to work the pressure going into the holding tank must be greater than that leaving the tank or you do not get the flow in that you need to separate the air from the water in the holding tank. Also there must be some pressure on the outlet to maintain or build pressure in the tank.

I think your test system is to small to build any significant pressure. You might want to experiment with a ram pump if you are looking to move water around.

If you watch Bill's vid again you will note  they had something like a 300 ft drive pipe with over 100 ft of drop going into a 55 gallon drum which eventually exploded to to high pressure.

The idea of the Trompe has been around since the days of the roman empire. I would imagine it was an accidental discovery when bringing water into cities via aqueducts then dropping it through a pip into a cistern. Well eventually that cistern pressurized and started blowing out fountain heads or some such. I would imagine the Romans may have even used them for cooling in some way.

I think the idea is to use water that drops from a high place, like say a waterfall. The higher the water drops from the higher your pressure can be. If my scuba training holds in this situation you get something like 14psi for every 33 feet of water depth/drop. I would imagine falling water might be more than this.

Now if you combine the Trompe with a ram pump I would imagine you can do lots more stuff too.

I wonder what kind of pressure you might get from a drain pipe on a skyscraper?

Ok this project is on hold for the time being as my sister needs to make up her mind where in the yard she wants to put it. I still need to build the bench to attach to it. The bench will not happen though until the location is determined.

Recently I was at a home depot scouting out materials I needed to screen red clay for my rocket mass heater project. While checking out the hardware cloth. I noticed a petite woman and her young young child checking out the 90lbs bags of concrete. I doubt she weighed more than that bag. I knew for sure she was not gona lift that bag into her cart so I walked over and asked her which one she needed and put in in the cart for her. I was really surprised at how thankful she was. For me it was just a matter of simple courtesy. Then later on when I had finished my shopping I saw here again at her car trying to figure a way to get the bag into her car and again I walked over and did the lifting for her and again she seemed inordinately pleased to be assisted.

I am always willing to help a person in need when circumstances allow and would live tho think most people are. Sometimes is it the small things that make the most difference.

I had a few days off and dug into this RMH project and have it nearly complete.

Glenn Herbert wrote:Looking good so far! You will get even better draw if you make the heat riser taller, ideally 3 to 4 times the height of the feed tube from the burn tunnel floor. Laying the riser bricks up on edge will get you more height while reducing the mass that has to heat up before the draft gets to its best.

My riser which is not shown in it's finished state here, will add another 26" to the bricks you see in the photo above. I also need to cut one of the top bricks in half then adding another layer pf brick to the riser area so when I add the barrel I will have enough room to install the duct where the bench piping will connect.

So a couple of short vids showing the drafting without the riser.

This was my first full weekend off in two years so I spent most of it playing with the RMH brick arrangement. I decided to go ahead and try my hand at sealing the blocks with some homemade mud plaster. It may not look very good but it does have the rockety draw I was looking for. I did get the riser packed with mud also but forgot to get a photo of it. I used a peace of 10" duct as the outer casing. I have a couple of 15 second vids showing the draw and sound of the rockety goodness but the forum does not allow an MOV file to be uploaded. I'll have to look and see what sort of vid file is allowed and see about converting them.