First time barrel stove evaporator questions

[Kombucha20]

Hi, this is my first barrel evaporator build.
I basically just took what I seen from YouTube videos and read but just a few questions to see if I can improve anything. I’ll post some pics of the stove. It’s not the prettiest yet still need to paint it but wanna get it running good.

The pictures are all sideways for some reason ??
But basically I have fire brick layering the bottom and then a bbq grate sitting on top of the fire brick
And it creates a space between the fire brick and the grate. The bung hole of the bucket it’s basically sucking air into the space for the draft. Just seems like I’m losing a lot of heat up the flue.
I only did one test boil so far because it’s been cold. my back pan is the hotter pan. I got it boiling but not a real strong rolling boil and my front pan was right around 99degrees Celsius when I stuck the thermometer in it. Most videos I seen it was always the front pan was the hotter pan. Any suggestions what I can do to get it burning hotter? I have a damper in the flue and tried to get it as tight as possibe where the pans sit, I made some runners for the pans it sit on. It’s pretty good but not 100% tight. I don’t have any smoke coming from any little gaps by the pan

Any suggestions are greatly appreciated
Again sorry for the pics, there not very good. I can take more if need be

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Thanks

[aamyotte]

I built the same thing as you. The only difference in mine is that I made a draft door that I can open or close. I didn't put a damper on the flue though. I have only tested with water since it was too early to tap.

I had the similar result with the rear pan boiled hotter.

[maple flats]

For a wood fired evaporator you should never have a damper in the stack. You want the most air you can get in to create the hottest fire. I hope that grate will hold up, you may end up needing one made of angle iron, welded about 1/4-3/8" apart, with the V point facing down. Then the ashes can fill the V and protect the angle iron. Aside from that, you have likely done well. Either block the damper fully open or better yet, remove it. Also, cut a larger air inlet under the grate, you will do best if it's the maximum possible, but then add a door to control the flow.
Back when I had my 2x3 arch and pan, I kept the draft door fully open.

[Kombucha20]

I leave my damper fully opened, the only reason I put one in is because I had one, when you say cut a larger air inlet so you mean like a bigger draft hole where the bung is?
I’ve seen set ups where people hooked up a blower in the bottom bung hole I was thinking about trying that. That’s why I didn’t cut a draft door yet, also i think I read where people put a perforated pipe in under their grate and hooked a blower to that so the o2 went right under the fire if I understood it correctly.

[aamyotte]

I leave my damper fully opened, the only reason I put one in is because I had one, when you say cut a larger air inlet so you mean like a bigger draft hole where the bung is?
I’ve seen set ups where people hooked up a blower in the bottom bung hole I was thinking about trying that. That’s why I didn’t cut a draft door yet, also i think I read where people put a perforated pipe in under their grate and hooked a blower to that so the o2 went right under the fire if I understood it correctly.
I used the opposite end of the barrel for the door. I made a cutout of 3x8 and added hinges to make a draft door. If I add a blower I will make a transition piece to fit the draft door.

The perforated pipe idea makes sense, hadn't thought of it.

[maple flats]

You can use a blower, or cut a larger draft hole, either will work. If using a blower make sure it moves enough air to make the fire real HOT.

[Big_Eddy]

Tell us about the fire.
How big a fire? What size wood? How many sticks?
This is not a wood stove or a camp fire. You want dry wood, wrist size or smaller and you need to fill that barrel about half full.
Heat going up the chimney is a given - lots of it.

Evaporating sap is not about fuel efficiency. It's all about time efficiency - which means you need to accept the fact that lots of heat is going up the flue.

[Gord]

Here's my rig. I bought a barrel stove kit, but didn't use the exhaust port. I wanted more space up top, so I made mine exhaust out the back. I added a blower too. Mine is variable speed so I can control the fire. I used a fireplace grate to keep air underneath. The blower keeps the front port clean and free of falling ash. So far, so good. I also beefed up the barrel by having a buddy of mine weld some strapping to the sides of the barrel. Added fire brick to the bottom and sides as well.

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[Balrog006]

Aside from sealing up gaps and cracks to keep the heat focused at your pans adding more insulation is your best bet. Brick up the sides as far as you can without them falling over from the curve of the drum and get some ceramic insulation and line the rest of the drum, door, sides all the way up to your pans, back and around the flue. Insulate as much as you can- this will keep the heat your fire makes on the pans better and longer.

[Kombucha20]

This is a good point, before I cut the holes for the pans and just had the flue, I was doing a burn to burn the paint off and I was just using scrap cut off pieces of lumber and man that thing was rocking. The flue was red with flames shooting out at some points. I only had a short piece of flue pipe then. When I did my first test boil I only used some shavings from my planer and then small round logs. My next run I’ll use more kindling like stuff

[Kombucha20]

This is my long term goal, I’ve been using all free stuff I’ve had, but I just wanna keep adding as I go

[Kombucha20]

That’s a nice set up! I was gonna go out the back with the flue but I thought it would draw better on top, I won’t have a lot of sap to do this year so the smaller top will work for me. I have another spare barrel and that’s probably the way I’ll go next build

[Z/MAN]

This is a good point, before I cut the holes for the pans and just had the flue, I was doing a burn to burn the paint off and I was just using scrap cut off pieces of lumber and man that thing was rocking. The flue was red with flames shooting out at some points. I only had a short piece of flue pipe then. When I did my first test boil I only used some shavings from my planer and then small round logs. My next run I’ll use more kindling like stuff

All I use is cut off 2x4-6's. I get them from a modular home builder that is happy to give them away. I get 12 GPH off my 2x3 with this extremely hot burning wood. I do not need a blower either. If you can get scrap 2x's burn them!

[STP92x]

We have been using a very similar setup for 4 years now and it has worked great. We have made a few modifications over the years and the biggest difference was when we added forced air under the fire, it took the fire and the boil to a whole other level. A friend of mine donated a 2.5" steel pipe that we drilled holes in the and ran under our grate and out the back of the evaporator. We use an old hair dryer as our blower. If you can find a thick steel pipe I highly recommend adding forced air under your fire.

[Kombucha20]

We have been using a very similar setup for 4 years now and it has worked great. We have made a few modifications over the years and the biggest difference was when we added forced air under the fire, it took the fire and the boil to a whole other level. A friend of mine donated a 2.5" steel pipe that we drilled holes in the and ran under our grate and out the back of the evaporator. We use an old hair dryer as our blower. If you can find a thick steel pipe I highly recommend adding forced air under your fire.

That’s exactly what I want to do with a pipe under my grate. Why do your run it out the back of the stove tho?

[wobbletop]

It's a cooler area at the back of the evaporator and it gets it out of the way.
I just use 3" duct piping and a bathroom exhaust fan. They tend to be quieter than other fans. I drilled a few 1/4" holes in the duct pipe under the grate. They last a long time since there is usually cool air blowing through it so it doesn't burn out.

[Galena]

Aside from sealing up gaps and cracks to keep the heat focused at your pans adding more insulation is your best bet. Brick up the sides as far as you can without them falling over from the curve of the drum and get some ceramic insulation and line the rest of the drum, door, sides all the way up to your pans, back and around the flue. Insulate as much as you can- this will keep the heat your fire makes on the pans better and longer.

Balrog was dead right about the insulation thing - my barrel stove has teh ceramic insulation, sand and firebrick - holds heat amazingly well, I can stand next to it when it's running a boil at 235 and not get blasted by heat. And it came up to temp within 20 min on relatively little wood.

[82cabby]

Balrog was dead right about the insulation thing - my barrel stove has teh ceramic insulation, sand and firebrick - holds heat amazingly well, I can stand next to it when it's running a boil at 235 and not get blasted by heat. And it came up to temp within 20 min on relatively little wood.

Absolutely. I ran a barrel evaporator for many years and the biggest single improvement I made was carefully insulating it as much as possible. It cut my firewood usage in half. Second biggest improvement was forced air.

[Kombucha20]

Does the pipe under the grate need to come out the back of the stove? I have a cinder block kinda just under my flue at the end of my grate just to make the fire box a little smaller. I was thinking about resting a perforated steel pipe on the block with the end capped so all the forced air will be right under my fire

[Galena]

Absolutely. I ran a barrel evaporator for many years and the biggest single improvement I made was carefully insulating it as much as possible. It cut my firewood usage in half. Second biggest improvement was forced air.

I've heard that forced air works wonders, but I am using a 6in smokepipe so have a great draw. There is also an air vent in the door and a cast-iron stove grate sitting atop the firebrick so air gets in underneath and helps keep it going. Considering that I burned snow at 235 and it took approx 20 min to come up to that temp, I am VERY happy with my insulated barrel evap!

[red4476]

So did anyone make a ramp up towards the chimney out of sand or simply stack brick to make the heat go up towards the pan? Plan to insulate my barrel this year. Also how do you keep the insulation on the door?