new guys rig

[Gary R]

I did 4 modifications.

Damper in steam stack, added holes to the end of preheater gutters, added 1" of blanket under rear 1/3 of pan, changed preheater outlet so that sap has to come out of the top of the the upper manifold.

It sucked! I could barely get a boil in the back of the pan. I figured it had to be the blanket. Thankfully my good neighbor, Jim Brown stopped by. We decided to lift the pan and remove the blanket. It worked great. Full boil in the pan. The fire is great. When you turn off the blower to fire you see flame shooting out the nozzles on the air over manifold. I can not increase the distance between the pan and the blanket without major modifications. Now I wonder what could the boil be like with more space to get the heat towards the back?

Preheat temperature is only 160+ deg. My hood is not tight with a few openings as it covers the front pan also. I need to see inside to see how things are going. If you had an external float, you could keep this closed and have a higher preheat.

[3rdgen.maple]

Gary soumds like you are making improvements. I am however a little confused about you wanting to have a bigger opening under your back pan. I always thought you wanted the heat as close to the bottom of the pan therefore having minimal space between the pan and arch floor. The right size stack will suck that heat right to that back pan. I have less than 1 in space under my flues and it takes very little effort to get that flue pan to a rolling boil from one end to the other. Now when I had a flat pan setup I filled the back of the arch right full of sand within 2 inches to get it to boil better. The way my grandfather had it set up there was like 8 inches and the back 2 pans never boiled. Guess I should mention there were 4 flat pans and a finishing pan on the arch. I am just wondering if your stack diameter is choking the heat a little on you. 160 degrees on your preheater sound pretty good compared to the 130's you got before. I think it is easier to get to say 130 then it takes alot more effort and inginuity to get every gegree higher. Good job man sounds like you are having fun. You might want to consider some firebrick as well atleast split brick. It is about half the price at a concrete yard, than it is from a maple supplier. It helps protect your blanket and it retains alot of heat as a bonus.

[Sugarmaker]

Gary R
The preheater is working! but like others said may need a few tweeks to improve, if you want. I agree that the cold sap should go in one corner and the hot sap should come out the opposite upper corner. Maybe you can run the return line back to the bottom and across to your hood outlet port. Or just drop down and back across to the other side of the hood?

The drip tray system looks real nice. I like the use of stainless for the "v" rather than the aluminum I used.

The damper in the stack, I think is a must and should be able to trap as much steam as possible under the hood. I close my damper until steam starts to come out under the hood and then open it until the steam coming out the cracks in the hood is minimal.
I get 200 deg sap from my preheater.
I don't have a clue what the efficiency improvement is? I hear 10 to 15%. Its got to be better than cold sap going into the boiling pan.
I think I have about a 4-5 inch incline in my 4 foot preheater.
Nice job welding in the port for the probe.

Regards,
Chris

[vermaple]

Gary,
I'm having a little trouble visualizing your set up, but it seems like you are using a flat pan. If that is the case you must leave area (cross sectional) under the pan for exaust of smoke. As an example if your rig is 24"wide with a 7" stack 38+ sq in, you should have about 1.75"-2.0" under the pan. The under pan opening needs to be measured inside the arch.
It sounds like you may have dampered your fire to much with the blanket in. Trial and error is what it takes to find what works best.

The 160 degrees in the preheater may be about as good as you can get without a tight hood. Thats much better than 40 degrees. Looking the pictures of your preheater, it doesn't look like you have a vent in it. Without a vent a preheater will vapor lock from gases released from sap. A vent tube from the higher manifold higher than the highest level of sap in your storage tank with an open container on the end of the tube. Keep up the good work!

vermaple

[Gary R]

The preheater is vented. If I decide to change the pre heater, I think I'll change the outlet position. I'd move it to the other side and run the pipe back across the pan. Doing so would add almost 2' of piping. I also will add new pan gasket. I currently have a thin piece of blanket for the pan to set on. I'll go to the full 1". This should give my some extra clearence under the pan.

Chris, all the "V"'s for the drip tray are aluminum. I thought everyone could tell by the beautiful welds

[Gary R]

I wanted to follow up on how things went. It was a poor season so I did not have any long boils. The preheater change and air over has added at least 2-3 gph. I am now adding wood every 10 minutes. I do have some issues. The way I plumbed the air to the air over, most of the air comes from the back of the fire box. A larger manifold and bringing the air to both sides of the manifold would fix that. The blower needs to be shut off to fire now. I did not add dampers to over or under air. That would help balance things. My wood is split small. With larger wood I'm sure I could go to 15 minute fire. All in all this does work well. I can keep a full boil easily in the whole pan. The fire brick floor is awesome. No chance of warping and the holes keep clear. Preheat temp does only go to 165. That would be because my hood is open on the front.

[matrob]

Gary,
I'm looking at a similar modification because my pan near the stack won't boil. Are you saying you swapped out the blanket for the brick nearest the stack. Was the blanket hampering the boil? I know I need a bigger stack, but would like to figure out what other changes I should make at that time. My blower at the fire puts plenty of air in the fire, but I'm only getting 300 -400degrees at the stack. I don't have over fire air.
Thanks,
Matt

[Gary R]

Matt,

In my opinion, each homemade evaporator works a little different. There are some guidlines as to area under the back of the pan and stack size. But I think each builder has to tweak them to burn the best. With a blower on it, and only 300 degrees, it sounds like you have a restriction. Too small of stack or not enough clearance under the pan. I had the same problem when I put too much blanket under the pan. I only had about 1" space. It wouldn't boil. I opened it up to 2" and it boils great. Try some changes and boil water. Good luck!