Post by invention1 on May 29, 2018 13:18:04 GMT -8
So here is a theory, and I have a flame-proof suit on, so gentlemen, start your flamethrowers! I will bask in the glow.
A batch rocket stove, say 8", with standard sizes per the regular calculator. Somewhere in the middle of the firebox there is a primary air inlet, and a rather standard floor channel.
Here's where it gets interesting though: The first thing I want to add is a way to sweep the ashes and crud down the drain - an ash box below the firebox. Why work so hard to shovel out ash, when you can just sweep it up? Lots of DIY pellet stoves have this feature as they need regular cleaning. Like any stove really.
But the most interesting part is this - what if that air inlet was also a place to slide in a pellet basket? There's a pellet feeder behind the basket. It is a convertible pellet/wood rocket stove. Witht he right mix of primary and secondary air, a port, a proper flue, all insulated with ceramic fiber.
Most DIY pellet stoves are welded up out of steel. They can't possibly get hot enough, without a meltdown.
"OH, PELLET STOVES ARE NO GOOD, THEY REQUIRE 120V WHAT IF THERE IS NO JUICE?" a common objection. 12V gearmotor, out of my junk box, rated at about 1 RPS, runs on a fencing battery, which runs on a little charger. Id would run for days and days without 120VAC. I actually have two of the little gearmotors, I think I got them on Grainger a long time ago for another hack. Timing - well, I do a lot of electronics let's just say that isn't going to be a problem, I'll get that figured out. It may well be that the pellets are still run in batch mode, with a manual switch until I get the timing figured.
Other objections to pellet stoves - electronics failing, noisy fans, and so on, won't be much of a problem here. If the electronics fry, well I built them, I can fix them. No fans to make noise. Conventional wood stove draft. I have a really good tall chimney, if anything too much draft, so I'm not worried about getting enough combustion air to the stove.
Pellet basket is removable. If we are burning wood, it gets replaced with a firebrick with a proper air gap for primary air, also removable for cleaning and so on.
Pellet baskets burn out, mostly the rods people use. I happen to have a large box of 8" X 3/8" ceramic rods, originally for electrical heaters. These things can go cherry red indefinitely, without failing. The walls of the pellet basket are still stainless sheets or plates, and they tend to last OK. Pellet basket will be fragile, not for use with wood, only pellets. Spacing between rods about 3/16". Lighting will be manual with a propane torch, same as wood. The rods are fragile, they will fail because some dunderhead mishandles them, not because they burn out. After a few broken rods, we'll get used to handling them. Stainless threaded rods hold the basket assembly together, those rods are out of the fire so they should last OK.
Well, the junk box just continues to provide. What about doors? I'll need an airtight wood loading door. I just happen to have scored several large (9" X 16") stainless steel electrical disconnects at a Habitat. Watertight, hosedown Nema 12. They had no idea what they had, these things are worth $300 each and I got them for about $1 a pound. One of them has now already been hacked into a servicable wood loading door, with the back cut out, a wood stove gasket in place of the rubber gasket original. It's a wood loading door almost the same size as the inside of an 8" rocket stove firebox. The door is 9" x 16", whereas the firebox is meant to be about 11.5 wide by 17" tall. I can work with that as a wood loading door. It sports a cool "ON-OFF" label on the outside, and a big steel handle to lock it shut. The inside will have ceramic fiber to keep it from sucking out too much heat, and also because I want the label to stay.
I'll need an airtight door for the pellet hopper, to prevent burnbacks into the hopper. (Yeah, I researched this, that's the fix) Burnback is worse with hardwood pellets, which I will be using. Airtight door - well I already have one - and it is made of stainless steel. Another electrical disconnect. This part doesn't get hot so the original rubber gasket can stay.
There will be some other cleanout doors and so on, I'll make out of doors I can buy, say barrel stove parts. Ugly but servicable.
Next post some dimensions and a sketch.
A batch rocket stove, say 8", with standard sizes per the regular calculator. Somewhere in the middle of the firebox there is a primary air inlet, and a rather standard floor channel.
Here's where it gets interesting though: The first thing I want to add is a way to sweep the ashes and crud down the drain - an ash box below the firebox. Why work so hard to shovel out ash, when you can just sweep it up? Lots of DIY pellet stoves have this feature as they need regular cleaning. Like any stove really.
But the most interesting part is this - what if that air inlet was also a place to slide in a pellet basket? There's a pellet feeder behind the basket. It is a convertible pellet/wood rocket stove. Witht he right mix of primary and secondary air, a port, a proper flue, all insulated with ceramic fiber.
Most DIY pellet stoves are welded up out of steel. They can't possibly get hot enough, without a meltdown.
"OH, PELLET STOVES ARE NO GOOD, THEY REQUIRE 120V WHAT IF THERE IS NO JUICE?" a common objection. 12V gearmotor, out of my junk box, rated at about 1 RPS, runs on a fencing battery, which runs on a little charger. Id would run for days and days without 120VAC. I actually have two of the little gearmotors, I think I got them on Grainger a long time ago for another hack. Timing - well, I do a lot of electronics let's just say that isn't going to be a problem, I'll get that figured out. It may well be that the pellets are still run in batch mode, with a manual switch until I get the timing figured.
Other objections to pellet stoves - electronics failing, noisy fans, and so on, won't be much of a problem here. If the electronics fry, well I built them, I can fix them. No fans to make noise. Conventional wood stove draft. I have a really good tall chimney, if anything too much draft, so I'm not worried about getting enough combustion air to the stove.
Pellet basket is removable. If we are burning wood, it gets replaced with a firebrick with a proper air gap for primary air, also removable for cleaning and so on.
Pellet baskets burn out, mostly the rods people use. I happen to have a large box of 8" X 3/8" ceramic rods, originally for electrical heaters. These things can go cherry red indefinitely, without failing. The walls of the pellet basket are still stainless sheets or plates, and they tend to last OK. Pellet basket will be fragile, not for use with wood, only pellets. Spacing between rods about 3/16". Lighting will be manual with a propane torch, same as wood. The rods are fragile, they will fail because some dunderhead mishandles them, not because they burn out. After a few broken rods, we'll get used to handling them. Stainless threaded rods hold the basket assembly together, those rods are out of the fire so they should last OK.
Well, the junk box just continues to provide. What about doors? I'll need an airtight wood loading door. I just happen to have scored several large (9" X 16") stainless steel electrical disconnects at a Habitat. Watertight, hosedown Nema 12. They had no idea what they had, these things are worth $300 each and I got them for about $1 a pound. One of them has now already been hacked into a servicable wood loading door, with the back cut out, a wood stove gasket in place of the rubber gasket original. It's a wood loading door almost the same size as the inside of an 8" rocket stove firebox. The door is 9" x 16", whereas the firebox is meant to be about 11.5 wide by 17" tall. I can work with that as a wood loading door. It sports a cool "ON-OFF" label on the outside, and a big steel handle to lock it shut. The inside will have ceramic fiber to keep it from sucking out too much heat, and also because I want the label to stay.
I'll need an airtight door for the pellet hopper, to prevent burnbacks into the hopper. (Yeah, I researched this, that's the fix) Burnback is worse with hardwood pellets, which I will be using. Airtight door - well I already have one - and it is made of stainless steel. Another electrical disconnect. This part doesn't get hot so the original rubber gasket can stay.
There will be some other cleanout doors and so on, I'll make out of doors I can buy, say barrel stove parts. Ugly but servicable.
Next post some dimensions and a sketch.