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Jroma 12-09-12 10:29 AM

Help to build a prototype "Wood Stove" secondary burning in Brazil
Dear colleagues
"EcoRenovator" I am new here and I thank the help they can give me and there is a wonderful forum like this.
My name is Jorge and I live in Brazil.
First I would like to thank any help possible and apologize for my bad English (google default) and also by the large number of issues.
If my questions are not understandable, I may try to clarify the issues during discussions.
I believe some will find it strange the presence of a resident of a tropical country, this forum asking about the "construction of wood stoves secundary chamber".
I know that each choice will lead to advantages and disadvantages, but I need the opinion of people who understand the subject, beyond the Internet, like myself.

Jroma 12-09-12 10:30 AM

But first I will explain the reasons for wanting to build one of these "Wood Stoves" here in my country:
Brazil is a big country and there are areas where the winter is very cold for our standards.
I live in a small town called Irati (indigenous name which in Portuguese means "bees that make honey."
this town is in the southern state of Paraná, southern Brazil, about 100 miles from the state capital, Curitiba.
The winters here can last 3-6 months with temperatures between - 6 degrees C and + 12 degrees centigrade and is a mountainous region where it can rain over 100 days a year.
Our homes are not built to have a good protection against the cold, nor have good heating systems.
Here is common to use iron stoves they call "economic stoves" (I even bought one to experiment with heating and firewood consumption).
Not models are very primitive and all have fireplaces.
But the results of my tests were not very good.
In the few years in which I live, I noticed that a large number of families that live in this area, spend lots of firewood in inefficient stoves that return some smoke into our homes.
My goal here is to have your help to build a prototype from the use of a scrap "wood burner Stove" type secundary chamber, which in the future can serve as an example for others to change their heating systems for efficiency in heat production, with less wood consumption.

Jroma 12-09-12 10:30 AM

In Brazil there are companies that manufacture or import devices manufactured here called "heaters", the latest generation.
But as the market is relatively small, els are expensive for most Brazilians.
've Got a lot of information about the systems of "double firing" and I believe that I understand well the principles of operation of the system.
*Yet here I am a "pioneer" in building a legitimate "Home Made" from scrap.

Jroma 12-09-12 10:31 AM

My starting point:

1 Box Steel - reuse of a steel box size that I think is reasonable for the initial project.
I intend to lea serve as "Fire Box", which was used for storing tools in an old farm tractor.

Box Specifications

It is a steel box and already assembled with welded front door hinges. Steel about 3/8 inch thick.


Height: 64 cm
Width: 46 cm
Depth: 40centímetros

A square tube of steel plates about 3/8 polegade that fits on existing box.
This tube has 1 square meter in length.

My first thought was:
Building a wood stove in the style of a reform on which lí right here in this forum, ( 4. uses a secondary air supply or through the use of tubes in the shape of inverted "L", with perforated pipes of the secondary air supply coming from bottom of the wood stove.

This would be a mechanism associated with a "deflector plate" would help in the process of "second burn"

Coat the inside with small bricks, which are easily found in the Brazilian market.
Solder the "Square Tube" on the box and take advantage of already burned in dases lower box making run inside the tube generating better utilization of heat.

Jroma 12-09-12 10:31 AM

My questions are many, so I need help.

What would be the best solution?
1 - Use only the bottom box with the heat coming straight to the chimney?

2 - Option 2 - Solder the second pipe on the box using baffles to more than 2 times the exhaust box low travel longer before reaching the chimney? Would there be so good suction?

3 - Option 3 - cutting the top cover of the box "bottom fire" and cause the second combustion occurs in the "square tube" which would be welded on the box?

4 - Option 4 - Make the entire process of burning double in the bottom box and just pass the chimney inside the square tube to recycle the heat? In this case the plate too thick could not cool down the stove too neutralizing the effect of the second burning?
5 - Option 5????????????????

Jroma 12-09-12 10:32 AM

Block basic problems that are independent of whether or not to use a second pipe on the primary box.


*1 - I've read that the "hood" of the chimney must not be greater than 8 inches, for good cause suction of exhaust.
I could wear a 5 inch exhaust pipe with stainless steel that I found in the scrap, or be very close to the suction of the exhaust gases?

2 - the front door of the box is quite large
(Approximately 64 centimeters by 46 centimeters)
I would like to opinions about the best way to create a "sealed door."

I thought so far in 2 outputs

Option 1 - Solder a "frame" plate with approximately 8 to 10 centimeters wide at the front of the box, so that could stick two or three rows of "cords" fiberglass sealing flame-retardant, and able tentsar a door completely sealed.

Option 2 - weld the existing door and cut a slot for a smaller door already prefabricated.

As manufactures at home (with the help of a welder with turner course) a control primary air efficient, sealed and with good regulation?
*Well excuse me gentlemen again bad English and the large number of questions, but I appreciate the help of heart because as I said I want to share the learning and who knows fam'lias help low income to heat their homes better, with fewer hazards , more savings and more efficiency.
Thank you for your attention and
Big hugs to all


Jroma 12-09-12 10:42 AM

1 Attachment(s)
Example more stove heater as used herein homes

Jroma 12-09-12 10:44 AM

As I said before, these stoves have chimneys and they are even good, but in my tests I realized that a return to both smoke inside the house.

Geo NR Gee 12-10-12 10:53 AM

1 Attachment(s)
Welcome to Ecorenovator. It is hard for me to understand what you are looking for as you seem to have a pretty good handle on this project. My stove that I converted to a secondary burn was like you mentioned. I use it almost everyday. After the fire box is hot (about 10minutes) you do not see smoke exiting from the chimney pipe. In fact, I see a lot of heat escaping that I would like to capture with something like this.

Here is a description:
Installs into flue of your wood, oil or coal furnace or heater. Magic Heat Reclaimer consists of 10 heat-exchanger tubes and a thermostatically controlled fan to blow warmed air into the room. Turns on at 150deg and off at 110deg F. 115 Volts. Produces 225 CFM and 8000 to 30,000 BTU. Peak performance is maintained by the use of Flue Stove Pipe cleaner (our Item# 172801). 18 1/4in.H x 10 5/8in.W x 14 1/4in.D.

Jroma 12-10-12 07:13 PM

Dear Geo NR Gee
Thank you for your attention

I'll try to simplify my doubts dividing the questions in parts.

Part one
I have a box that I believe will allow me to make a wood stove double chamber. So far I have a lot of information about how to try to build it.
The first fundamental question is: Could I use a chimney of 5 inches for a project box with 64 X 46 cm by 40 cm deep or should I go to 8 inches or more?

The second question concerns the use of a second thick steel box (measuring approximately 40 cm by 9 mm thick) resting directly on the output of the second burning gases, welded or supported with other fund on the first box, which would to continue burning for about a meter.

I think of something like the wood stoves double barrel, only in this case the "second barrel" would be a vertical structure of bulk iron would receive the fire resulting from the second firing took place in the main box.
Does the idea make sense?
Or is it just an idea theoretically logic without having good chances to work

Thank you for your attention

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