Post by D. Anthony Dayringer on Dec 19, 2018 12:42:09 GMT -8
I finished my first rocket heater!! Been using it for about a week. I tried to upload pictures here but it wont let me. I even made really small image files. Still wont let me upload. So here is a link to a post I made at the permies forum that includes some pictures (I plan to add more later.)
permies.com/t/98342/built-rocket-heater
I heard there were some more technical minds on this forum. And I would like to get thoughts from those minds!
I am building a heater and a mass separately because I had most of the materials for the heater, and we needed heat NOW. So this is a rocket heater without a mass. For now. Which means it is running almost all the time.
I have the type of mind that likes to do things that people say you can't do... so this build breaks some rules about the proper way to make a rocket heater. That is a big part of why I want some technical input.
The body is made from regular 4x8x2 concrete bricks. And I used quikrete mortar mix for mortar. So all the masonry is based on regular portland cement. From my understanding portland cement breaks down around 600F. I thought I could get away with this because the burn tunnel is lined with 2 inch thick 2600° ceramic fiber blanket. The feed tube is lined with firebrick from tractor supply. The sides of the feed tube are not lined with the insulation... only fire brick (I now believe this was a mistake. As after a long (10+ hour) burn 4 or 5 days after the initial burn a crack is forming by the feed tube. This is partially due to my inexperience with masonry as the crack is not really a crack, but a separation between the mortar and the brick itself. The outside of the heater gets about 150 degrees after a few hours of burning. The absolute hottest the outside has gotten was 250 at the sides and 280 at the front by the feed tube. This was around the feed tunnel that does not have the 2 inch ceramic insulation. And it was when I noticed the crack. It will not be getting that hot anymore. That was after a 10+ hour burn and I had neglected to empty out the ash in the burn chamber so there was less air flow, and I had the feed tube mostly covered by a brick to make up for the lesser flow... which held in more heat in that chamber making it get much hotter higher in the feed tube. When it is clean there is enough airflow in the feed tunnel to keep it fairly cool. I can stick my hand right in the feed tunnel when its running properly.
This is also a 4 inch system. The CSA of the feed tube, heat riser, and the vertical exhaust pipe are all between 12.5in² and 16in². Depending on whether it is cylindrical or rectangular. (4x4=16 and 4 inch circle is about 12.5)
The heat riser is an 8 inch duct with the same 2 inch 2600° ceramic fiber blanket wrapped on the inside. Giving it a 4 inch ID.
The feed tube is 13in tall and the heat riser is 43in tall with a 2 inch gap at the top. I made the riser a bit taller than necessary to help with draft. Plus since it was close it was just easier to make the riser tube 3 ft (plus 7 inches to the bottom of the burn tunnel.)
The exhaust (not a) manifold is a 4x10 rectangle that goes into a 6 inch circle (I plan to use 6 inch tube in my mass to help reduce drag). It then reduces back to 4 inch for the vertical exhaust that runs about an inch away from the bell(not sure if this is the correct terminology, Its what the drum usually is... but I used an old water heater... so... not a drum)
Right now the system is working AMAZING (as long as I clean the ash out of the feed tunnel). There is a good draft when the system is cold. I have more than once accidentally put out the fire on newspaper when trying to light the heater because I put the paper in to quickly and the draft blew out the fire. This gives me hope that I will be able to add a mass and still have enough draft.
Ask questions. Give me critiques. If you want specific info or pictures let me know and Ill get what I can. Ill post the pictures on the permies post since it seems I cant here...
Looking forward to responses!!
Editing to add videos of build.
permies.com/t/98342/built-rocket-heater
I heard there were some more technical minds on this forum. And I would like to get thoughts from those minds!
I am building a heater and a mass separately because I had most of the materials for the heater, and we needed heat NOW. So this is a rocket heater without a mass. For now. Which means it is running almost all the time.
I have the type of mind that likes to do things that people say you can't do... so this build breaks some rules about the proper way to make a rocket heater. That is a big part of why I want some technical input.
The body is made from regular 4x8x2 concrete bricks. And I used quikrete mortar mix for mortar. So all the masonry is based on regular portland cement. From my understanding portland cement breaks down around 600F. I thought I could get away with this because the burn tunnel is lined with 2 inch thick 2600° ceramic fiber blanket. The feed tube is lined with firebrick from tractor supply. The sides of the feed tube are not lined with the insulation... only fire brick (I now believe this was a mistake. As after a long (10+ hour) burn 4 or 5 days after the initial burn a crack is forming by the feed tube. This is partially due to my inexperience with masonry as the crack is not really a crack, but a separation between the mortar and the brick itself. The outside of the heater gets about 150 degrees after a few hours of burning. The absolute hottest the outside has gotten was 250 at the sides and 280 at the front by the feed tube. This was around the feed tunnel that does not have the 2 inch ceramic insulation. And it was when I noticed the crack. It will not be getting that hot anymore. That was after a 10+ hour burn and I had neglected to empty out the ash in the burn chamber so there was less air flow, and I had the feed tube mostly covered by a brick to make up for the lesser flow... which held in more heat in that chamber making it get much hotter higher in the feed tube. When it is clean there is enough airflow in the feed tunnel to keep it fairly cool. I can stick my hand right in the feed tunnel when its running properly.
This is also a 4 inch system. The CSA of the feed tube, heat riser, and the vertical exhaust pipe are all between 12.5in² and 16in². Depending on whether it is cylindrical or rectangular. (4x4=16 and 4 inch circle is about 12.5)
The heat riser is an 8 inch duct with the same 2 inch 2600° ceramic fiber blanket wrapped on the inside. Giving it a 4 inch ID.
The feed tube is 13in tall and the heat riser is 43in tall with a 2 inch gap at the top. I made the riser a bit taller than necessary to help with draft. Plus since it was close it was just easier to make the riser tube 3 ft (plus 7 inches to the bottom of the burn tunnel.)
The exhaust (not a) manifold is a 4x10 rectangle that goes into a 6 inch circle (I plan to use 6 inch tube in my mass to help reduce drag). It then reduces back to 4 inch for the vertical exhaust that runs about an inch away from the bell(not sure if this is the correct terminology, Its what the drum usually is... but I used an old water heater... so... not a drum)
Right now the system is working AMAZING (as long as I clean the ash out of the feed tunnel). There is a good draft when the system is cold. I have more than once accidentally put out the fire on newspaper when trying to light the heater because I put the paper in to quickly and the draft blew out the fire. This gives me hope that I will be able to add a mass and still have enough draft.
Ask questions. Give me critiques. If you want specific info or pictures let me know and Ill get what I can. Ill post the pictures on the permies post since it seems I cant here...
Looking forward to responses!!
Editing to add videos of build.