What to do with the evaporator?

[MaxJ]

We bought all the sugaring equipment with the property a few years back and now I see where there can be some modifications done to the system. The evaporator must be 30+yrs old, newer pans, and the brick has been replaced but things are just not right. The rear is a 24"x48" flat pan and the front pan is a 33'x24" divided barrel pan or what would fit on a Leader 1/2 pint evaporator.

Here's the main problems:

The inside measurements between the brick is only 16", the top outside rail measurement that the pan sits on is 23" so I can see I'm loosing 30% of pan right there.

The fire box is 36" long with hardly no wall at the back before the slope going to the stack. Loading wood in it's easy to have wood burning up in the slope area (which is the only way to get enough heat to get the rear flat pan to a mild boil.)

The solution: Have the frame of the evaporator frame made wider to accommodate the 24" pans, then install a blanket and replace the brick?
Have a wall installed at the back of the firebox to force the heat up to the rear pan?
Right now with 13.5 sq.ft of pan I'm lucky to obtain a 10 GPH boil which is making for a long day.

I can't justify buying a new evaporator at this time when I think this one could be just refigured into a better working one. So is the best way to improve this or am I dreaming?

[Russell Lampron]

You need to widen the arch to accommodate the 24" pans. It should be wide enough so that only a 1/2" of the pan on each side sits on the rail. Then you need to build a ramp starting at 24" back and slope it up to within an inch of the bottom of the pan. I think that the ramp in mine is at a 45* angle. Fill the area behind that with vermiculite to the top of the ramp and slope it down at the rear just in front of the stack. I haven't measured it but I think that the bottom of my firebox is only 16" wide. I have found that 16" wood works the best.

[MaxJ]

Thanks for the reply Russ, I just measured the unit and the fire box is 16" x 33", then the sarts for 24" putting 14" at the front of the rear pan going up to 5". I'm wondering if I can use these fire bricks to build up the slope? They're 9" x 8"x 2 1/2"thick.
13807

[Bricklayer]

They will work

[MaxJ]

Thanks Bricklayer,

i'm just thinking I'd stack them in for now as it'll all come apart come spring for the frame rebuild. How high should I stake them given there's 14" of space at the beginning of the ramp?

[Russell Lampron]

Stack them so that there's about an inch between the top of the bricks and bottom of the pan. Start the bottom of the slope 2 feet in from the door. Use 16" wood for fuel.

[MaxJ]

When I finish this boil the pans are getting cleaned, and I'll get the bricks in place.

[MaxJ]

Well I have had two very frustrating days with equipment, the evaporator is giving me grief. I built up the ramp by about 9" with a 45 degree angle for 24" then I cut the 5+" that was under the rear pan down to 2". But I have no heat by the time I get to the stack it's almost touchable, the front pan is boiling and I can get a little boil half way on the 48" flat pan. I didn't have a lot of time to cut the brick so I set them in and then built up the difference with sand.

Would the sand be absorbing the heat faster than pan?

[Big_Eddy]

Max
Pictures!!
If I read this right - you have 2' x just under 7' of arch.
You had a 36" firebox, which you have now reduced to 24". At the 24" mark, you have a vertical back wall, then a 45 degree slope up to 2" below the bottom of the pans. From there to the stack you have sand in the arch 2" below the pan bottom.
The sand may absorb some heat for the first 15-20 mins. After it heat-sinks, it has no further impact.

I'm not sure what you mean by the 16" bricks and 23" rails. Do the bricks go right up to the rails, or is there a space above them?

If I understand your setup correctly, then you are close enough with the arch setup that you should be able to accomplish what you want.

Next 3 things to look at

Draft (chimney)
Air Supply
Wood.



Draft
Without a blower, the stack determines how much air is sucked into the arch. For a 2x7' arch, you should have an 8" or 10" chimney, and you need at least 12' of stack. More would be better.

Air Supply
I didn't see anything about a blower, so whatever ash door you have needs to be wide open. You want at least 100 sq inches (6x16, 4x24) of open area for air to enter the arch under the grate. You need a grate and it needs to have at least 4" of clear space under it. Remove all ash any time it builds up.

Wood
The rule is wrist size, but I like it smaller still. For a 2x arch, anything bigger than a 2x4 will burn better if split again. Fire often (<10 mins) with less wood, instead of loading it up and waiting. If you look in the crack between your two pans or between the back pan and the chimney, you should see flames going by. If not - then your wood is too wet / large, or you don't have enough draft / air opening.

Stick at it - we should easily be able to get you up to 15gph - 20gph

[MaxJ]

Max
Pictures!!
If I read this right - you have 2' x just under 7' of arch.
You had a 36" firebox, which you have now reduced to 24". At the 24" mark, you have a vertical back wall, then a 45 degree slope up to 2" below the bottom of the pans. From there to the stack you have sand in the arch 2" below the pan bottom.
The sand may absorb some heat for the first 15-20 mins. After it heat-sinks, it has no further impact.

I'm not sure what you mean by the 16" bricks and 23" rails. Do the bricks go right up to the rails, or is there a space above them?

If I understand your setup correctly, then you are close enough with the arch setup that you should be able to accomplish what you want.

Next 3 things to look at

Draft (chimney)
Air Supply
Wood.



Draft
Without a blower, the stack determines how much air is sucked into the arch. For a 2x7' arch, you should have an 8" or 10" chimney, and you need at least 12' of stack. More would be better.

Air Supply
I didn't see anything about a blower, so whatever ash door you have needs to be wide open. You want at least 100 sq inches (6x16, 4x24) of open area for air to enter the arch under the grate. You need a grate and it needs to have at least 4" of clear space under it. Remove all ash any time it builds up.

Wood
The rule is wrist size, but I like it smaller still. For a 2x arch, anything bigger than a 2x4 will burn better if split again. Fire often (<10 mins) with less wood, instead of loading it up and waiting. If you look in the crack between your two pans or between the back pan and the chimney, you should see flames going by. If not - then your wood is too wet / large, or you don't have enough draft / air opening.

Stick at it - we should easily be able to get you up to 15gph - 20gph

Thanks for the reply Eddie

The fire box is still 33" long and between the brick it's 16". The wall at the back of the fire box used to start 3" above the grate which are 3pcs of 2"x 2" sq. tubing 29" long, I added a 2" piece of round pipe as there was too much gap in grate and the fire was basically falling right through to the ash box. This reduced the space but still allows some spacing between the tubes.
Eh! BRAIN FART! I had ash build up over the grate-NOT ENOUGH AIR FLOW!

The wall at the back of the fire box is now 12" then slopes back 24" @ 45 degrees

The chimney is 14' or more for height, but only 6" going up for 8' to where it's connected to a 8" insulated pipe and continues up through the roof. I bought this operation from the previous owner which did some upgrades from the original builder in 1985 so it seems that it was easier to had a larger pipe to the small 6" pipe instead of increasing the hole in the arch.
13965

[Burnt sap]

Very good info Eddie that should put him on track. Nicely done you even helped a problem I'm having thanks! :cool:

[MaxJ]

Thanks again Eddie, it's just hard to breath if something isn't getting enough air. Boil going better.:)

[Big_Eddy]

Thanks for the reply Eddie

The chimney is 14' or more for height, but only 6" going up for 8' to where it's connected to a 8" insulated pipe and continues up through the roof.


I really think a 6" stack is too small for a natural draft 2x6 or 2x7 arch. You need to pull lots of air into the arch to get a rip-roaring fire and that restriction is going to reduce your draft substantially. 8" seems to be the norm. If you had a blower, 6" would probably do, but without I'd see what it would take to replace that section of pipe with 8".

After that - it comes down to wood and firing technique.