Dave Lot

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since Oct 05, 2014
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Recent posts by Dave Lot

After repeated firings, the rocket heater is now all dried out and burning nicely.
Since I have made the burn chamber .5 of an inch smaller in one direction - there is no smoke back, or puffing at all.

Loading the stove up with cardboard, gets the stove really hot !

This is why I warn people, when building one of these stoves, to leave plenty of room around the barrel.
2 years ago
I had to urethane some window frames out in the shop.
So, I went out at noon, and fired up the portable rocket heater.
At noon, it was 28 degrees F.  By 1 pm, it was 40 degrees F.  By 3 pm, it was around 65 degrees in the shop, and I started urethaning the wood.
After that, it quickly reached 72 degrees, and I had too open the door too cool off.

In total, I used 8 pieces of 1.5 x 1.5 x 36 inches plus 2 - 2x4s - 48 inches long - as a test for back burn - there was none.

It works.

Edit.  After burning the stove full out for most of the afternoon ( 5 hours or so ), the outer bricks around the fire box ( the ones with 2 inches of perelite inside ) only reached 90 degrees F.  or so.  Perelite is a REALLY GOOD insulator.
2 years ago
After a week of sitting in the shop, it was time for a full on burn.

No leaks, and very good draft.  6 inch pipe thruout the build.  The one thing I did differently is too make the entrance to the burn tunnel .5 of an inch smaller in one direction.  That increases the draft in that area, and I can now load up the burn chamber as full as it will go, and I have no smoke back or back burn issues at all (so far).

I also find, that the 4 or 5 feet of bare chimney pipe is losing almost as much heat as the mass was absorbing.  I know that I cannot tell what the inner temperature is on the stove pipe, since it now gets hot enough to melt the regular stove thermometer I was using, but the new chimney thermometer I picked up, is telling me that it does not get over 200 F . I do notice a difference at the top of the chimney outside, as there is no smoke, no steam, nothing to see - as if the stove is not even running.

On the plus side, with that large slab of concrete covering the manifold, my coffee stays hot ...

2 years ago
After taking apart the hastily built mess that I made, I took my time, and mortared all the surrounding bricks with high temp brick mortar.

After that, it was just a matter of building up the surround for the manifold, and topping if off with a slab of concrete.

Added a few more bricks too weight down the chimney placement ... so it wont move too much, and did a small test burn.  Warmed up the stove, to help it dry out, and checked for leaks.
2 years ago
Yup, make the manifold big....
2 years ago
My 6 inch rocket had 6 inches of clay perelite around the entire fire box, too get it nice and hot for a good clean burn - after 6 hours of burning  (1100 + F) , the outside brick (another 2 inches thick) would still be at room temp.
The mass was a measured 6 inches of clay/sand from pipe to pipe - then I added another layer of brick for durability (+ another 2 inches or so).

After a full 6 hour burn - working out in the shop - the entire mass would be 100 F - just like a heating pad.

The thinner the mass, the faster it heats up, and the hotter it gets.  My mass was fairly thick, so it would take longer too heat up ( would not even feel a 2 hour burn).  4 inches sounds about right.

edit :  sorry did not answer the question - add all the mass together - just because its brick, its still mass.
2 years ago
I have posted this in other threads, but would like to add it here.

I built a 6 inch RMH, and it so happens, that the barrel was located 3 feet away from an electrical panel.  Once the mass dried out, and the stove was "rockety" - it was normal too see the top of the barrel hit 1100 F - hot enough to get the face of my electrical panel too hot too touch - just from the radiant heat coming off the barrel after an extended burn.

You need the barrel to radiate the heat away from the stove - that gives you your draw up the chimney - but when my plastic vapor barrier started to crinkle up and melt - ya know your in trouble ....

2 years ago
me personally, I tend to build it first, then ask questions as too why its not working....
You find out a lot of new things that way.

As for your cooler pipe crossing under the burn tunnel, first question that comes to mind, is how high do you want your stove too be ?
The very next thought is, people underestimate the insulation value of clay and perelite.

I am thinking, you build your stove like in the picture - the way you want too - with an air space under the whole thing - don't want too burn your floor - add to that a 4 or 5 inch layer of perelite clay - again, so you don't burn your floor - lay in your chimney pipe - then add another layer of perelite clay to insulate the heat from the burn tunnel and keep it hot. - only put the perelite clay between the tunnel and the chimney -  Then you can build your burn tunnel as usual.

The first problem, is how high is it going to be . . .  2 inch air gap - 2 inch concrete pad - add 4 inches of perelite clay - add a 6 inch duct - another 4 inch perelite clay - then the burn tunnel ....

You would still want the chimney to exit and go straight up near the stove barrel - the radiant heat from the barrel will encourage the chimney draw - adding to the draw of the stove...

I will include a warning, that when this thing is burning right, that barrel could get hot enough to glow red - i.e. 1200 F plus - so anything closer than 4 feet from the wall, and you could burn your building down ... My stove was 3 feet away from an electrical box, and the box was too hot too touch after a long burn @ 1100 F.  Leave air gaps in between the stove and the walls - for air flow, and so you can stick your hand in there and see how hot it is.

With the added layer of perelite clay insulating the burn tunnel away from the cooler chimney, the stove should hit temperature, before it even starts to effect the chimney pipe, and by then, it will just add to the draw of the stove....

just my opinion . . .
2 years ago
After thinking about it for five minutes, I realized, that if you want a good sturdy stove, you have to start with a good solid base....

Too that end, I have started removing the outer bricks, and mortaring them into place - to make a solid frame too work from.

Also, while I have the heat riser off, I am going to be laying the bricks flat - instead of being on there sides, and very unstable and tippy.

Unfortunately, the weather has turned colder, so we will see how it goes . ...
2 years ago
Here is an update on the wheelie rocket . . .

I went to hook up the chimney, and as soon as I touched the thing, the stove and the chimney separated. ...  bummer.

2 years ago