Homemade evaporator questions.........long

[Pete S]

I read through an earlier post and didn't find quite the answer(s) that I was looking for so I thought I'd post:

1.) I have located an old "parts cleaner" cabinet. It's a nice metal box and resembles a chest freezer. It's dimentions are: 38" long, 21" wide, and 28"tall.

2.) Tomorrow I want to get out the abrasive wheels, and gas axe, welder and accumulated old bed frames, and start making my evaporator fire box.
a.) How close should the "fire grate" be to the bottom of the pan?
b.) I'm looking to vent with a 6" pipe. should the pipe be near the top back of the evaporator? OR should I design a "baffle" that forces the heat "up" then down, and out the pipe?
c.) Should I build an arch, or will a grate for the fire to burn on be fine? The pan is nearly as big as the top of the evaporator.

This needs to be a low/no budget as it seems to be more fun/challenging, but if I can build in some nice features that provide additional noticable functionality, I'm interested.

Thanks in advance for any/all responses!!

[WESTVIRGINIAMAPLER]

If you put the grates about 20 inches from pan, this would give you 8 inches to clean out ash. Also might recommend you line the cabinet with ceramic blanket or 1/2 or full firebrick as the metal won't last too long and will be red hot and dangerous if you don't.

If you can put a grate in it along with the firebrick, it would work the best. If you can build up a wall in the middle of the firebox or fill the back part of the firebox with dirt or sand, this will help push the heat up. Mount the pipe as close to top of firebox as possibley.

[VA maple guy]

Pete, I have both a ceramic blanket and fire brick on and in my barrel evaporator. Your evaporator will be a whole lot more efficient with either one of these or both of them.. If your cabinet has any paint on it that is not high temp, you should first burn it as hot as you can to get rid of it or your first batch or two of syrup may pick up a real bad off flavor. I learned that the hard way.
Just put your pan on it and fill it with some water so you don't ruin your pan. I have a seven inch stack that vents out the back and as near to the top as i could get it. You may also want to use about eight feet of stack to help it draw. Good luck with it and keep us posted on how it works.


Gerry

[Pete S]

You really brought up a very important point! I was planning on "burning off" all the residues/paint/grease prior to utilizing this as an evaporator, as I could only imagine the "flavor" of the syrup!

BUT...............Should ONLY the bottom of the pan be exposed to the fire??? I was "planning" on setting it up so that the pan would "hang" into the firebox.

OR should/could I create just a reinforced opening that the pan "bottom" be exposed.

Actually that would be better/easier to grab the pan and dump the individual batches.

Additional feedback would be great!
Thanks!

[WESTVIRGINIAMAPLER]

If the pan hangs in the fire, it will boil faster but you would have to keep it full or the sides would scorch really bad were the sap is boiling up on the sides and if you keep it full, it would boil over. :?

[Pete S]

Thank you SO MUCH for that tip about the pan being into or on top of the fire!!!

OMG that would have been a disaster!

I feel armed with the necessary knowledge to continue with my construction of the evaporator.

Thanks to ALL for the good advice!!!

Oh, and just to share: I needed to burn this thing off/out as it is painted and has (had) a large fiberglass repair in the bottom, (as that's why it was in the scrap) "after it was readied for use.
Anyway, I was welding a patch into the side, and began to smell LOTS of smoke. YUP, we started the burnout process in the shop! Drug it outside, with all the BLACK smoke belching out, put the fire out and peeled the fiberglass out..............man what a mess! Now we're good, as the inside is nice and free from combustibles. What a KODAK moment!

[VA maple guy]

Pete , I have two pans on my barrel evaporator, both of them are recessed into the fire. my larger pan is made out of copper, it will scorch a little bit if you let the level get to low. I like to keep around one inch in it. The pan i had befor the copper one was stainless, It never got scorched but it would build up a small amount of light brown stuff on the sides. My small or syrup pan is made out of aluminium and has never scorched. I will be easier to dump the pan it if sits on top. I have a draw of on my copper pan so that's not a problem for me, my syrup pan does have to be lifted off to empty it. If i were to build another evaporator i would set the pans on top.
Gerry

[maple flats]

Brandon is right. You should not have the pan down into the fire or where ever the sap level is there would be a burn ring that would make the syrup off flavor. You will be better off if you figure a fill system so you can burn at 1-1.5" depth max but only if you can maintain it there no matter what else is going on around you.

[Daren]

My setup has 3 recessed steam table trays and yes they do build up "burnt" sides where the sap boils up onto it. It is difficult to clean up, but has not caused any off flavors as I run them pretty deep until I run out of bulk sap. This keeps the level right about the same as where they are recessed. (they sit up on 1 inch angle iron above the top, so there is about 2 1/2 inches of depth that does not recess into the fire box. That leaves enough head space over the sap to prevent it from boiling over). The dark stuff really starts to accumulate late in the boil when the levels drop. The boiling sap "rolls" up onto the hot sides and you can hear the "Sizzle".

So, after much long winded explanation, i too would only recess them a few inches into the firebox so you can run the sap a couple inches deep (safer than 1.5 inches to prevent burning it all up) and still not scorch the sides as much. I have to admit that i can really get them roiling with them recessed. I get about 10 gallons per hour, not exactly sure as this is the first year with the preheating, but should be close if not a little more. Good luck with the project.

[royalmaple]

Daren-

Really enjoyed the pics of your operation. What did you use for fittings to tap into the blue barrel you are using for gravity feed? Also what did you use for the transition from plastic tubing to copper. I was looking to do the exact same thing. Couldn't find anything at local Home depot that looked like it would seal the barrel etc.

[WESTVIRGINIAMAPLER]

Daren,

It definitely boil faster with the pans recessed because it makes it a little more like a flue pan. If that works for you, the that's awesome and stick with it. You know what your are doing and a great setup! :D

[brookledge]

Royal maple
bulkhead fittings can be cut into just about anything to give you pipe threads in various sizes Usually from 3/4" to 2"
I've used them and they work great.
Keith

[royalmaple]

Keith-

Thanks, can I pick this bulkhead fitting at a local hd store. Or are they only at maple supply co.

[brookledge]

Royalmaple
McMaster-Carr carries them from 1/2" to 4" But they cost a little more than Bascom. Try the Maple Guys for a price. I'm not sure if Home Depot or Lowes would have them. Another location would be an orchard supply store or any one that sells alot of plastic tanks.
Keith

[royalmaple]

Thanks I'll check it out.

[NH Maplemaker]

royalmaple. On my blue barrels there are 2 large screw in caps on one end, If you look close, one of which should have treads in the center of it ! It should except a 3/4 inch tread to pipe plastic fitting!! ( may be 1"fitting, can't remenber)Srew in fitting then just punch or cut out the plug, it should come right out!
I have used a few of these in years past as small gathering tanks. Placed a short pice of 3/4 black pvc pipe on fitting in barrel and a 3/4"ball valve on the end of black pvc pipe with another 3/4 fitting srewed in opposite side of ball valve. When I got back to the sugar house,I would hook hose from vacum sytem to barrel,open a valve on releaser and the one on barrel and away sap would go into storage tank! I hope you can under stand what I'm trying explain,as it maybe hard to picture ! I still use vacum system in the same way when buying sap from others,only now it goes though a water meter that I got from brookledge last year. It tells me just how much I'm buying!
Hopes this helps!!

Jim L.

[Daren]

Royalmaple....I used a brass quick disconnect hose adaptor that I attached to a threaded reducer sweated to 1/2 inch copper tubing. I got the threaded reducer at a local hardware store. I just took a clear piece of tubing and put on the "hose repair" kit ends to make a small length to go from the barrel to the fitting. That way, If it gets crazy cold and I have not got the time to completely finish the sap in the line, I can disconnect and drain it into a gathering pail to prevent freezing in the tubing. It is also very convenient to be able to remove the whole thing for sanitizing it. Especially late in the season.

[Daren]

oops royal....you asked about the barrel side.....I picked up a 3/4 inch faucet, used a 3/4 inch auger bit to make a clean hole and just screwed it into the plastic. It did not leak as I drilled into the thicker part on the bottom of the barrel and as I screwed it in, it kind of tapped itself. It is very sturdy, but I put a little sealant along the outside edge of the faucet where it snugs up to the barrel just in case. The hard part was finding food grade sealant. Most hardware stores do not have it.

[royalmaple]

Daren-

Thanks. I'll see what I can come up with.
I appreciate the help.

Once I get something in motion, I'll take some pics to show what I have come up with.

[royalmaple]

Daren-

Does your feed line / preheater line go into the top section of your arch then back out to the 3/8 flex line end?

Or does the heating occur just from contact to the stove?

Thanks,
Matt

[Daren]

royal....contact with the pipe and evaporator. It does not keep up all that well if you have to really "catch up" if you let the sap level get too low, but if you keep it tailored, it warms it up pretty well. I will need to add some more length for next year though. If I could fashion something removable, I would have run it into the evaporator and back out again. That would get it too hot though.