First practice run. Fired up new evaporator. boiling slower than expected, any though

[Azitizz]

Hi there, so heres some pics of the newly built evaporator from scraps and an old fireplace. I got it fired up tonight and had it going for a good hour and a half to two hours with water (tap water) to test it out.

It was boiling a lot slower than I hoped. Im wondering if anyone has any design suggestions or Ideas in order to improve its efficiency. Basically I couldn't get it to boil on 3/4 of the pan. it boiled only above the fire. The sides of the stove got glowing red hot once I put some 2x4s and dry soft wood scraps but it only just got boiling then and the rest simmered.

I haven't installed the refractory supplies yet, a 2' x 8' ceramic blanker (1 1/2" I think) and a couple dozen firebricks as well as a pan gasket. the space between the pan and the bottom of the arch where the heat passes through is about 5". I thought with the ceramic blanket and perhaps ashes under it it would bring it to close to 2".

I was also wondering how the chimney affects air pull. the stack i built has an 8" opening and goes down to a 6" chimney, would it be better to keep it at 8"? Would a higher chimney make a difference.

Thanks this site is great. i wouldn't have been able to build what I did if it werent for browsing all the info available on here.

Looking forward to bringing it in the shack where shell stay. I have to get things right while shes in the shop...times a ticking... and once its in the shack, no more welding or anything that requires electricity...

[GramaCindy]

Hello AZITTIZ, Congratulations on your acquisition of the property. I am just a minor player here, newbie last year also. A few observations that I made are; The stack needs to be at least two times the length of your evaporator, (I think it's 2x, something to check into) Get the blanket, bricks and rail gasket on, it will help to keep the heat INSIDE the arch, thereby heating the pan much better. Also, I'm not sure why or if it matters, (I think it does) get that firebox directly under the pan if at all possible. If you can, add air to the firebox. Last year I used a standard household fan in front of my ash pan door. It really helped a lot, although I'm not sure if you can do that with your set up. Just my 2 cents

[Greg Freeze]

The taller the stack, the more draft you'll get...minimally it should be 2x the length of your pan. You're going to find that it will work more efficiently after everything is insulated. Like you said, right now you have to much space inbetween your pan and arch at the back end. Once you force those hot gases closer, the boil will be better. I wouldn't fire it again until you insulate or you might warp something. Looks like you've done a good job with the supplies you could find. Welcome to Maple Madness lol.

Greg

[Paperman]

Well from the looks of it you are not getting much in the way of direct flame contact with the pan. In a commercial set-up you have the flat pan with direct flame on it and the back flue pan that pulls the heat out with the huge area of the flues. With your pan you really dont have much surface area to absord heat from the basicly hot air. Can you block off your lower firebox with a grate sitting on top of the opening between the two and build your fire closer to the pan? Maybe cut a few holes in the front to allow more air it and more stack for a draft. Also keep in mind we are not heating a house. More air, more draft, faster burn is more heat to boil more sap.

[ehafkey]

How much space do you have between the bottom of the pan and the arch? I would narrow that down to about 2" and definitely get the insulation in with some bricks. You should check your stack temp you maybe losing the heat up the stack.

[Azitizz]

Thanks for all your replies. I was waiting for someone to give me the 2x the length of pan-stack rule.. Its welded now, I made it as tall as I could with the material I had, Had I made it any taller, I would have had to use many more smaller pieces of varying thickness. not fun to weld.... Also I built the pan halfway over the firebox/stove thinking i could finish the syrup on the stovetop, I think Ill build a valve onto the pan to be able to pour off the sap with a slight tip of the pan towards the front.

I'm hopeful to hear about all the confirmations regarding insulating.

What should a stack temp read for one to determine loss of heat or not?

Thanks again...

[ehafkey]

If your stack temp is 600* and the back of your pan is not boiling your heat is going up the stack.

[70 Buick]

Insulating will surely help with heat loss

[Azitizz]

If your stack temp is 600* and the back of your pan is not boiling your heat is going up the stack.

What would be the cause in this case, and what could one do to rectify it?
Thanks..

[70 Buick]

Look around in this section Homemade
I read where someone had the same problem recently
they put in some kind of a deflector plate to direct the heat up or something like that
It was in the last week or so I read it so its not far away

[Greg Freeze]

What would be the cause in this case, and what could one do to rectify it?
Thanks..

Too much room under the back of the pan. Build it up with fire brick to keep the gases closer to the bottom of your pan...around 2".

[sugar ED]

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[Big_Eddy]

How deep was the water in the pan. Would be a huge difference in boil rate between 1" deep and 3" deep.

What kind of opening do you have for air? Should be under the fire and should be as large or larger than the smoke-stack.

Do you have a grate in the bottom to build your fire on?

I agree with reducing the space under the pan to the minimum needed - 1-2" is plenty.

With a grate, lots of air and less space under, should be able to get that pan boiling well if you run it 1-2" deep.

That said - I think I'd be looking to reweld the stove to have the firebox directly under the front of the pan. A couple of things about the current design bother me - you're bending way down low to add wood, and there's not much space in there to add a lot of wood. Also, I reckon that top surface is going to be the cause of a number of nasty burns over the years. It's right at shin / knee height, and heaven forbid someone places their adult beverage on it while you're boiling.

Just my 2.3 cents.

[sams64]

That firebox is a looong way from the pan. It will be a lot of work, but I would consider moving the fire box up & back. Also your flue box looks very flat as it moves toward the stack. There is generally a gradual slope that reduce volume as the gas travels throught he system. As the gas moves throught the system to the stack it cools and loses volume. This could allow the gas to stall/ less circulation of heat. The longer stack could create enough draft to pull the gas through the system better.

The metal work looks great and half the fun of doing it yourself is making it run. I need to brush up on my welding so I can go from concrete blocks to steel next year.

Sam