Building an evaporator

[Rabbit River Sugar Shack]

We are building a new evaporator out of concrete blocks, firebrick and 5 "steam table pans." It is very close to the "Do It Yourself Evaporator" at Mother Earth News .com. Everything is coming together very well, but I have two questions that I need to have answered. How close to the bottem of the pans do I build the arch? Should it be 1 foot, 10 inches, 6 inches and so forth? The main fire box is about 24 inches square and 3 1/2 cement blocks high, from that point how high do I bring the arch, and at what angle? Should it come up at a 45 degree angle and then level off under the pans, or should it be gradual up to the flue? Any information would be a great help.

[jtcinv]

I have been using a rig with 2 steam table pans for a couple of years. I only tap 25-30 trees. I have some pictures on the website listed in my profile. I have been building it up so there is about 16-18" between the ground and the bottom of the pans. I am not happy with this arrangement and will either get an evaporator this year or will build it up quite a bit more to allow for a wood grate so I can get some air under the fire. I have found it key to use thinly split wood or dried out sumac branches that burn fast and hot. I have gotten my costs down to about $200/gallon this year, not including beer, coffee, gas, or my time.

Jeff

[Maple Flats]

If you want to match what a commercial unit is I will give you the approx. design of my Leader 2 x 6. The fire is on grates with a large air intake under the grates, about 6" x 12". The firebox is about 16 x 24 " and the grates are about 15" below the pan bottom. At the rear of the firebox it tapers up to about 1" clearance under the flues in the flues pan but flames also pass between the flues so you would need more that 1", maybe a 1.5" space for all flames to pass thru and the entire width of the arch. This space would go the entire length until the stack. Making a flared stack helps spread the heat. Once the flames/smoke are in the stack it reduces to 7" on my 2 x 6 and the stack height is designed to be 2x the evap length or in my case 12'. However in actuality I have 14-15' of stack because my sugarhouse is taller and need it to go above the roof. I hope this helps. If you need more exact measurements I can measure them next week as I will be working there all week getting things ready and doing some improvement cuttings.

[RileySugarbush]

I have been using a rig much like that for years. Gradually adding pans so that now I have 4. Blocks should be protected by fire brick or they don't last. I have a fire grate in the first 24", then the base of the arch is stepped up like the profile you see in real arches. It works very well, despite the hot sides of the pans scorching a bit near the finish. Syrup filters out and tastes fine. Also, with four pans it takes a bit of maintenance to keep levels correct.
I've added some poor man's drop flues to the back two pans. See some photos at:

http://web.mac.com/jabushey/iWeb/Riley%20Retreat/Maple%20Sugaring.html

[WF MASON]

I thought I'd seen every flue pan known to man ,,,,,now I have.Wow

[ibby458]

Excellent workmanship!

Flue pans like that were made commercially sometimes in the distant past. I like to paw around thru old collapsed sugar houses (with permission), and I've seen 2 of them. I would think they might work a bit better than the normal flue configuration. More surface area in the fire.

I've thought of building one like that, but I was thinking of 2" copper pipe, with caps soldered on. THen I priced 2" copper pipe - and started looking for a used evaporator!

[Fred Henderson]

I am very interested in this article. How long would those copper tubes be? They look to be about 5".

[ibby458]

There you go, Fred! With your talents, you could build one to fit your existing arch!

If I can't buy the rig that I'm using this year, I may build one using that method.

[RileySugarbush]

Fred,

I've made three of these pans. The first, for myself, I used 1" copper water pipe and caps, about 7 inches long. That worked out OK but the caps made it a lot more work. The next two, I used some water hammer arresters from Home Depot for a couple of $ each. These look like little bullets with a pointy end that is spun closed. The open end is reduced to half inch diameter, so I cut that off and flared the 1" opening so that it seated nice in the pans. A little less area bu a lot easier and cheaper to build. I gave one to a friend and he is having good luck with it too. These pans evaporate at about 2 to 2.5 times the rate of an unmodified steam table pan.

John Bushey

[WESTVIRGINIAMAPLER]

John,

Great job! What size is your total setup and what kind of evap rate do you get?? :D

[Fred Henderson]

One thing that concerns me is when the is no sap for days to boil, evrything freezes. Takeing my pan off and draining it is out of the question. Because my arch has a heat dam/ damper maybe I could close that and just hang a light buld in there. You certainly have given me some ideas to ponder.

[WESTVIRGINIAMAPLER]

Fred,

With a heat lamp bulb, it would definitely not freeze.

[RileySugarbush]

I haven't done it, but I would not be concerned with the tubes freezing since they are open on top and not that long. I'm boiling this Sunday. I'll try the experiment for you after that.

I'm just a weekend sugarer. I have 30 taps / bags, and make only 5 to 8 gallons a year. When I have my fire well stoked I am guessing I can approach 15gph, but my arch is pretty crude, and I end up with a big pile of coals on the grate and poor air flow near the end of the day. I just installed a blower under the grate, so this Sunday should be interesting! I'll add a picture of the set up later.


John

[ibby458]

I REALLY like the concept of drop tubes, so I did some research & Calculations.

McMaster-Carr lists the same water hammer arrestors for BIG BUCKS, but on the same page of the catalog was Stainless steel sink tail pieces. 1-1/2" x any lengthy you want up to 12" long. THe top is pre-flared. I got a friend with a computerized plasma cutter, so cutting disks to solder in the bottom would be a snap. At $3 for 8", it seemed reasonable.

I'd want about the same surface area as a 2x5 flue pan, so I started fiiguring. To match 8-60" flues, you would need 199 of those tail pieces! At $600 for the bare tail pieces, let alone the awful amount of soldering I would have to do, It puts a used evaporator in very good light, indeed.

It sure is a perfect upgrade for a steam table pan, but it seems to be a bit less attractive for a larger evaporator.

[Fred Henderson]

To apoint I have to agree with but on the other hand knowing that you made something with your own hands that works very well gives one a deep feeling of satifaction and also make syrup.

[RileySugarbush]

Here are some things to think about:

I looked all over the net to find better prices, but ended up buying out hte stock in two local Home Depots. I don't recall the price, but it wasn't horrible. Far better than McMaster was.

The water hammer arresters are nice because they are closed on one end, but you have to flare them yourself. I made a little jig to do that quickly.

The 1" diameter is as small as you want to go,and really is too small. It seems like a good idea to maximize surface area, but the narrow tube works like a percolator and shoots sap like mini Old Faithfuls. I lose some sap that way since my pans are small and a lot of the tube are near the edges.

The stainless drain tail pieces sound good. For simplicity, you could crimp the open end and solder seal them. Makes for a crevice that would be hard to clean, though.

It's fun to think up alternatives and come up with these home built designs. I'm adding force combustion air to my arch with a $24 Walmart electric leaf blower and a Radio Shack lamp dimmer for speed control.

In the end, though, I think I've taken this concrete block/steam table pan thing as far as it can go. I really need to get a real evaporator and tap a few more trees. I've got an old camp bunk house 50 feet away that just needs a cupola and some glass replaced and I'd be set.

[RileySugarbush]

It can work! I sealed up the door and put sheet metal on the insides behind the firebrick to minimize flames blowing out the sides. I layed some 4" ducting under the filler in the arch so I could put the blower out of the way behind the arch.

Results? 15gph when I paid attention and kept the split hardwood fed regularly. It really cut down on the bed of coals that would slow down the boil after a couple of hours. There is a short video clip here:


http://web.mac.com/jabushey/iWeb/Riley%20Retreat/Sugaring%202006.html

[Daren]

Hi John. I too have a steam table setup that I have boiled on for the last two seasons. I do not have any "tubes" on mine, but it seems to boil pretty good with the pans recessed into the firebox. The problem I have and from a few of the pictures you have linked, you have as well is the scorching of the pans and the resulting cleanup following each boil. I have been using good old elbow grease, but that does not get it all off. All it seems to do is take off the loose stuff. I finally have started to hand clean them, then use fine grit sandpaper on a sanding disk inserted into a drill to clean them the rest of the way. I am sure that this will ultimately reduce the service life of the pans, but nothing else seems to work, including commercial pan cleaners. What do you do for this problem, or do you not sweat the hard, really cooked on stuff. I just cant seem to get myself to start a boil with other than sparkling clean pans!

[RileySugarbush]

That black burned on stuff is pretty tenacious all right! I have gone both ways on this over the last 10 years or so. Some years I cleaned them up completely before each boil, Others I rinsed them out, scraped off the loose stuff and rinsed them again. In my experience, it doesn't make a huge difference in the syrup. Heck, the old iron kettle over the fire wasn't shiny clean and I bet the old timers liked their syrup, even if it was a shade darker. Actually, if you do the rinse, scrape, rinse and look at the last rinse water, it is pretty clear. Of my four pans, only the front two get significant build up. The other two, with the flue tubes, are sap pans.

This year I cleaned all four really well (to be described later) and on subsequent boils just cleaned them up as above. I don't like carrying the sooty things up the the house where I have a hose. My syrup comes out about the same to a tiny shade darker when compared to the stuff my neighbors make on a nice clean half pint. I say save yourself the aggravation and don't try sanding them clean each time. It's enough work just boiling on these pans!

Now for some cleaning.... Years ago, when I was using two pans, I put them in the self cleaning electric oven. First I washed all the loose soot off and scraped them as best I could. It worked great! I got confident and next time just threw them in after rinsing out the sugar. Big mistake! Soon, out of the small vent on the top of the stove , came a thin stream of vile yellow smoke. Then the smoke detector went off. And guess what? You can't open the doors of an oven when it's self-cleaning! I rushed out and got my 1.5 inch sump pump tubing and hooked up a shop vac out side, about 25 feet away. That fixed the smoke problem, but sucking through that corregated tubing set up a howl like a thousand banshees! Intolerable noise. My dogs were upset, too! Luckily, we were the only ones home. I finally found that by clamping down on the hose with a c-clamp I could slow done the air speed enough that it was quiet and still sucked out the smoke. It smoked for at least an hour of the 3 hour cleaning cycle.

Now when I want to really clean the inside of the pans I let them soak in muriatic acid, diluted with water. You can get it the hardware store. It is a bit extreme and hazardous to work with, but will eventually remove the toughest burned on sugar. As I said, only when necessary due to a really big buildup.

Have fun and experiment,

Trial & Error John