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Post by painterd on Dec 16, 2016 5:50:15 GMT -8
Update on my stove:
The stove is 3/16" mild steel, welded with a wire feed welder, I tacked all together to keep it from warping during the welding process.
The dimensions: The main fire box is approx, 14" x 14", and 24" long. The burn tube is now 4" square stock (1/4") going thru the front of the stove, with a 4" space in the back for the flame to come out. Then I lined the inside of the firebox with standard 9" X 4-1/4" firebrick (Menards) and made a 1" thick, high temp concrete baffle that sits on top of the fire brick, which is 6 from the front of the stove. I used high temp refractory cement (Menards) which I mixed with Perlite to make the baffle. The result is a light weight baffle that takes about 2500 degrees.
Now the flame burns inside the tube (Riley stove style burner) comes out the end of the tube, bounces off the back wall of the stove (also lined with fire brick) passes back to the front of the stove which continues to burn the gasses )and over the baffle, then back to the exhaust opening (4") It's just a simple rocket stove, only horizontal instead of vertical. I wrapped the stove with a 2" thin metal heat jacket and use a 480 CFM squirrel cage blower to blow the heat from the basement to the main level of my home ( much the same as a wood burning furnace) It works great. I get approx. 9 hours of heat with a 40 lb. bag of pellets on high. I also have a draft slide I can open on the front of the stove, so I can introduce air to slow down the burn and run it at a lower temp, which lets me control the heat output on warmer days. I can get as long a 16 hours out of a bag of pellets on low. Not too bad!
The 1/4" thick, 4" burn tube lasts one season before it breaks down and has to be replaced ( just cut it off and weld a new one on)
So.... Now I am in the process of changing the design, again... I'm using a 4" square burn tube inside the stove, only now it will be lined with fire brick to keep from breaking down. I made a 6-1/2" open ended box to hold the fire brick, and am welding it to the inside of the front plate on the stove. That's what will hold the fire brick in place. The first portion of the burner tube is still steel, but is bolted onto outside of the stove, so it is cooled enough to keep it from deteriorating from the heat. The fire brick is only 9" long so that is the length it extends inside the stove. That should still be enough to throw the flame out enough to fill up the inside of the stove and burn up the smoke before exiting over the baffle.
I'll post an update after I get it installed. It's below zero right now, so I'm gong to keep it running until later next week when it warms up to the teens above zero. That way I can take it all apart and get it up and running again before the house cools down. I'm glad I made everything bolt together so it easily comes apart for cleaning/ maintenance and fabrication. Dave
I'll have to figure out how to get a drawing of the stove so you have a better idea just what it looks like and how it works.
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Post by lightworker on Dec 17, 2016 15:48:57 GMT -8
Painterd:
I have been following your posts with interest. I initially followed this thread using Rectifier's carb design to build a l
pellet fired rocket bread oven. I am now retrofitting a hunter wood stove with secondary air burn and stainless heat exchanger to heat my outdoor hot tub. I like the option of changing doors and being able to burn with pellets. Am interested in seeing pictures of your set up as well as drawings. Keep up the good work in continuing to expand the use of the Riley style burner. You could line your burn tube with high temp fiber board use in kilns and foundry.
Lightworker
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Post by happycamp on Mar 17, 2019 13:10:15 GMT -8
Hello Painterd,
Im very interested in how you regulate the heat with the draft slide.
When you say you installed a draft slide on the front... do you mean on the front side of the fire box (rather than the Riley pellet burner)? And, do you mean by "front" the same side of the fire box that the Riley pellet stove connects to?
Thanks for any help you can provide!
Happy Camp
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Post by painterd on Mar 18, 2019 3:38:56 GMT -8
Happycamp,
Yes, the slide draft is on the front of the fire box itself, which allows air to mix with the flames, cooling the temp of the stove down and also, creating less draft, thus pulling less air thru the burner. It's very touchy. I open mine about 1/4" inch (with a 1" slide) which takes a little while before all the changes take place. Once it slows down, the flame is shorter and less intense. (I have a small 2X2" window on the front of the stove so I can see the actual flames burning inside)I'm concerned about the flame slowing down too much and not continuing a steady draft, so I rarely use it now. With the winter we had in Minnesota, I seem to use the pellet stove more during the coldest part of the season (running it at the hottest setting) and the furnace during the warmer days now (it runs cheap on natural gas)
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Post by painterd on Nov 24, 2019 8:54:38 GMT -8
I've since made another stove that is smaller, but puts out the same amount of heat and burns less pellets per hour. My design is much like the Wiseway stove (google it) but square instead of the triangular shape of the tube design. After years of research and design changes (I never thought I'd spend that much time on any one project) I finally came up with a burner design that seems to work flawlessly, burns hot enough and doesn't burn out and most importantly, doesn't clog with ash causing any back burn issues into the feed hopper. The design of the Riley burn tube and burner is the only one I found to work for me, so that's the one I copied to get started.
This is the Riley burner. Notice the square tube between the two round bottom tubes. I simply left that out left that part open on the l bottom. I didn't seem to serve any purpose when I had it in, so I just left it out on later burners. The pellets just slide down and are ignited by the incoming air that comes under the angled plate (where I left out the square tube) The two long round tubes let air in to burn up the smoke while it rushes by, making it a "rocket" sound. It really works well!
photos.google.com/photo/AF1QipPcfkZZQceHb-jsfucF3vP6dZLVqv1XCoMyqF0
One of my burners, pictured here, works that same way.
photos.google.com/photo/AF1QipOyGDdn4ey4DjGbP0p1Kk87FP9XiJgT0GLWa4I
My newer design works even better and burns hotter, which is what I needed for my new stove. The round tube in the center was replaced with just a piece of angle iron to keep the pellets lit and blows the flame forward.
photos.google.com/photo/AF1QipPelgLvruzlL9OJ2s8p1zJLkP5KwDv22bl2TVk
photos.google.com/photo/AF1QipNiETSN5KCf29oloYKExND9SEKYt5omM6os2z4 I replaced the two outer secondary tubes with a flat plate with holes in it and taped the air intake so the air comes in at the wide end and speeds up while it blows forward under the pellets and burns up the smoke as it exits. It also blows any ash forward so there is no buildup in front of the burner, keeping it burning steady and not plugging with ash. The holes in the plate also add air to the fire from underneath. This design seems to work perfectly and never slows down after running all day and night. I get 11 to 12 hours consistently out of a 40 lb. bag of pellets now with no back burn issues.
I'll try to get more (and better) photos up here and show the rest of the stove design. PD
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Post by Vortex on Nov 24, 2019 10:32:06 GMT -8
Would like to see the pictures but they are private and can only be viewed if logged into a google account. Can you please make them public.
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Post by painterd on Nov 25, 2019 16:04:17 GMT -8
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Post by Vortex on Nov 26, 2019 1:48:47 GMT -8
First ones not working still but second and third links work OK. Thanks
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Post by painterd on Dec 2, 2019 6:56:01 GMT -8
So, you see in the photos I posted, the idea behind how the burner works is, the pellets slide down the 45 degree slope and I light the fire thru the opening where the angle iron slopes forward. There is always a small draft from the chimney, so the flame always starts to get sucked into the stove slightly. It takes a few minutes for it to start to "roar" like a rocket stove. The tapered air inlet under the base plate of the burner forces the incoming air to shoot under the pellets, burning up the smoke. As the pellets burn up, the ash gets shot forward, into the ash pit ahead of the burner (not under it like most units) I also have holes drilled in the plate to help the pellets burn from underneath and keep the plate from ash buildup, which works perfect. The dimensions of that particular burner air not as important as one might think, but the part that makes it burn hotter or cooler is the gap under the plate where the tapered air inlet it. On that one it is 1/2 inch high and the taper is wide open in the back of the burner and tapers down to 1-1/4 inches where the air comes out past the burning pellets. I also have a 1/2 inch opening just ahead of the pellet feed tube (my feed tube is 3" X 2" square tube) which helps me to regulate added intake air to run the stove cooler if I need it. I rarely open it unless it gets too hot in the house. I have a few other burner designs I have used that also work very well. Some burn cooler ( using less pellets per hour) and some burn hotter, so I can switch them out depending on how cold it gets outside. The important point is the fact that I have designed burners now that DO NOT cause any back burn up the feed tube, which is what I worked so long to achieve. I did copy the burner design used in the Riley camp stoves, but I had one instance where is started to burn up my feed tube, (they also periodically have that problem) so that's the reason why I started to alter the design to work better. I now think that keeping the intake air coming under and forward of the fed pellets, keeps the flame from crawling back up the feed tube. I also get a complete burn with little ash and a nice hot flame with absolutely no smoke. My stack temp on the pipe going into the chimney is never over 200 degrees and the stoves usually runs around 800 degrees in the burn tube. I'll see if I can get some photos and dimensions of my stove up here this week, so stay tuned. PD
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Post by lightworker on Dec 2, 2019 13:14:43 GMT -8
Excellent work painterd! Looks like you have done quite a bit of development work with the Riley burner. Looking forward to pictures of your stove. Looks like I will need to pull out my mig and see if I can replicate your burner to test on my stove.
Lightworker
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Post by painterd on Dec 5, 2019 14:32:35 GMT -8
The slope of the burner is 45% and the small upside down angle iron "snout" is about 2" long. Under the burner is two 1/2" pieces of flat stock that taper from 4" at the rear to a 1-1/2" opening, where the air rushes under the flame and burns up the gases as the enter the stove. I also made a 1/2" X 3" wide opening in the top of my burn tube, (just ahead of the burner) that I can open to add more air to the flame, which actually cools the burn temp down a little. One would think that adding more air would make it burn hotter, but in this case, it adds more air to the flame going thru the stove, so there is less air being pulled thru the burner thus cooling it down a bit. So now looking back on all the burners I have made (I lost count) it all comes down to the amount of pellets, the air provided and how it's introduced into the mixture. I found if I made the secondary air too big, there was less air being drawn thru the pellets and they burned slower and cooler. It is much the same as a carburetor and that's how I approached the designs when I made them.
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Post by lightworker on Dec 5, 2019 16:27:05 GMT -8
Painterd: Unfortunately there is no drawing at your posted link.I see the link is gone now. I have a question as to why the burner is so long? I can see the front needing space for the pellets to completely burn, but the back? Perhaps the question will be answered by seeing the drawing.
Lightworker
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Post by painterd on Dec 7, 2019 7:36:16 GMT -8
Ya, I'm still trying to figure out how to post some of my photos and drawings (I'm not good with computers and that kinda stuff just yet) so be patient and I'll keep working at it. 
*The reason the burner ended up to be so long is I just had the piece of 4" flat stock to work with and I just never cut it off shorter. The idea is to make the under side of the burner to make the air rush into the burner better, to blow all the ash into the ash pit so there is no build up, which worked out perfect. The shape of the bottom portion of the stove looks kinda like this sketch: ________l PF l________________________________l l \ l \ burner l (excuse my typing skills) _________ \_________ l
_____________________ ash pit l l______________________________l -------------12"------------l----------- 24" --------------------------l
The burner (the portion with that angle on it) is positioned under the feed tube (shown with a PF for the pellet feed) and the 4X6" portion is my ash pit. The space under the burner is where the secondary air rushes past the pellets. The air comes in the opening at 1/2" X 4" and tapers down to 1/2" X 1-1/4" (approximate) so it speeds up as it comes in. Making it longer made it able to taper it more gradually. It actually starts about 5" behind the burn location. I have another one that has a larger opening where the air comes out, (which burns cooler) which tells me that the secondary air dictates just how hot the burn will be. Of course the size of the burner you're using also is a factor because of the volume of pellets that are burning at any given time. Once I had the burners fabricated so that they burned clean without plugging and causing a backburn in the feed tube (my foremost concern in the beginning) I then started to experiment with the size of the secondary air opening. Now being mine is a 4" system (4 inch burn tube) I find that the opening that feeds the secondary air should be smaller than the opening that feeds the air going directly to the pellets. It appears that the pellets need just enough air to keep them burning, which causes the draft to pull air in to cause a good secondary burn (in my case, under the pellets) The balance between the two is the secret to getting a perfect burn. That's when the light bulb in my brain came on - it's just a pellet carburetor of sorts! My first burners were just burn baskets made with 1/4" stainless rods (like all the ones yo see on YouTube) which I found to eventually burn the rods down too thin in a short time. But I also found out that the opening under the basket would dictate just how hot the stove would burn, so the secondary air is the key. I now see that I might just have to make a burner with an air control on just the secondary air opening. That should work as a "choke" on the carburetor so to speak!!! Gives me an idea!! ...I'll be back. |
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Post by lightworker on Dec 7, 2019 16:50:19 GMT -8
Painterd:
Thanks so much for the update. How is the steel of the burner holding up? With air flowing past it should keep the temps low enough to limit spalling. From looking at the burner it appears that the holes in the bottom plate are about 1/2" and in the centre 2" of the baseplate. Is that about accurate? If so it would allow some burning pellets to fall through and into to incoming secondary air.
As well, is the ash pit necessary as it seems that ashes would get blown out of the refractory burn tube and collect in the bottom of the stove? Or do I have that wrong?
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Post by painterd on Dec 9, 2019 11:40:46 GMT -8
Yes, the burner is holding up well for the past year or so since I started using it. There is some scaling on the "snout" angle, where it burns the hottest, but it should last for a while before I need to make another one. The holes in the bottom plate are 3/16" (I just staggered them in no particular pattern or measurement) so when the pellets burn up smaller, some them actually do fall into the secondary air steam and get swept into the ash pit where they continue to burn up. That's why I designed it that way. I didn't want any ash build up on top of the plate to slow the burn down, so that's why I drilled the holes. The air also blows thru the angle iron "snout", keeping the fresh pellets burning and also blow some of the burned pellets into the ash pit also.
This is a sketch of the stove as it is without the hot air jacket and legs I have on it now. (I hope this time you'll be able to click on it and it will work)
photos.google.com/photo/AF1QipMb-sbtVG2D2BlR3QVYL0I86BJYn_1NA657dk8 |
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