Assembling the Leader Evaporator Half Pint - Part 2 of 4

Part 2 involves assembly of the Reservoir Pan and the Boiling Pan, which are relatively simple and easy tasks, as well as installing firebrick in the sheet metal structure of the arch, a seemingly simple but very tedious task.

Draw-Off valve and thermometer at right front

corner of Boiling pan

I assembled the pans first, which only involved the addition of draw-off valves and thermometers ( 2 each) to the Boiling Pan, and the addition of what I am calling a "make-up feed valve" to the Reservoir Pan.  The only tool required is an adjustable wrench, and aside from the parts supplied with the evaporator, the only item required is a roll of teflon tape to seal the pipe-threaded joints.  Pictured is the draw-off valve and thermometer installed at the right front of the boiling pan, there is an identical set of valve and thermometer at the left rear of the boiling pan.  Having draw-off capability at opposite corners allows the flow through the Boiling Pan to be reversed, which minimizes the build-up of "sugar sand" in the Boiling Pan.  A "solid, sand-like material in the bottom of the syrup pan ... is sugar sand (commonly calcium malate crystals containing varying amounts of sugar).  Excessive amounts of sugar sand on the bottom of the pan can burn, giving the syrup an unpleasant strong caramel or bitter taste, and possibly damage the pan."¹  In our first two years as hobbyists we did not experience trouble with sugar sand build-up in our boiling pan, probably because we did not take the sap all the way to syrup in the boiling pan; we drew off the final 3-4 gallons from the boiling pan and reduced it to 12-16 cups of syrup on the range in the house.  I will have more to say on sugar sand and the operation of the evaporator in a later post.

If you look closely at the picture you might also find it interesting that the thermometer has an indicated range of only 0 to 50 degrees, and that the "7" is made to rest at the bottom of the dial as installed.  Syrup boils at approximately 7° F above the boiling point of water, regardless of altitude or barometric pressure.  Taking advantage of this fact, it is possible to adjust these thermometers to "0" when pure water is boiling in the pan, so that when "7" is indicated with the evaporator in syrup-making operation we know that its sugar content is approximately 66%.  With the "7" placed at the bottom of the dial, only a quick glance at the thermometer is required to know that the sugar concentration is at or near 66%; the final determination of sugar content is made by hydrometer (measure of specific gravity) or refractometer (measure of index of refraction).

Now on to the fun stuff, installation of the firebrick.  Let me just say up front that I am no mason!  And, eventually the job of "firebricking" the arch was done in spite of the inexperienced hand on the trowel.  This more difficult than it needed to be, for at least three reasons:

1) The instructions call for putting "about 1/8” on each edge of the brick to be installed and a skim coat on the side facing the metal," but the "fit" having done so is not as depicted in the instructions, and
2) I decided to fit the bricks to/around the nuts and bolt ends that protrude into the arch, versus simply pushing the bricks up against the fasteners, and finally,
3) the cement needs to dry at "room temperature (approximately 65°F)," and the only place I could maintain that temperature for extended periods of time was in the house.  This third difficulty was not a problem until it came time to move the arch to the sugar house!  The process of moving the arch to the sugar house will be included in Part 3 of 4.

Sample of brick instructions for floor of the arch

First came a leveling of the arch using a 4 ft. level and quarters for shims.  This is an absolutely necessary step, as was found out when the team and I were leveling the fully bricked arch in the sugar house; with the brick fully cemented into the arch, the arch becomes very stiff.  What I mean by "stiff" is that the arch will hold whatever shape it was in when the brick was installed.  In still other words, if it is not square and the top surface is not level before bricking, it will be extremely difficult to make it so after bricking.  The top surface is key, because when the Boiling Pan is mounted the sap needs to flow front to back, left to right, right to left and back to front, with equivalent ease, for the evaporator to work as designed.

Bricks laid out for floor of arch, with

refractory cement and instructions

The instructions (Leader Half Pint Assembly and Operation Instructions) depict a dry fit of the bricks, which is to say they do not allow for the 1/8 in. of refractory cement on the edges of the bricks.  If you count the joints between bricks front-to-back in this picture there are 6 (at 1/8 in. per joint that is 3/4 in.), and side-to-side there are 2 (1/4 in. at 1/8 in. per joint), which resulted in the need to do more trimming of brick to fit than was accounted for in the instructions.  Surely my joints were a bit wider than 1/8 in. which contributed to the need for additional cutting. Fortunately I did not need any additional bricks, in fact there was one Half Brick (HB) left over.

I worked in the order provided, which was Floor, Back, Side (1), Side (2), Front, and Firewall.  Things went more smoothly as I learned, but I definitely spent more time in this endeavor than anticipated.  As work was started, the included image shows the sheet metal and iron structure of the arch, the refractory cement (which was not nearly enough to complete the job), the instructions, and a "dry fit" of the bricks needed to complete the Floor.  With the use of 1/8 in. tile spacers during the dry fit stage I might have realized what was going on earlier, or perhaps if closer attention had been paid to the caveat in the instructions, which is, "Measurements in these drawings will vary depending on the technique used in bricking."  Well of course measurements will vary, why didn't I think of that!

Left side; (L) bricks dry fit, (C) brick 8 relieved for protruding nut/bolt, (R) brick 8 installed and cemented in place

Those pesky nuts and bolts; I was simply not content to only push the firebrick up against them, for among other reasons there would be a 1/2 in. gap between the brick and the sheet metal shell of the arch.  So, like is done when installing drywall around an electrical outlet, I measured and made cuts, in this case drilled 3/4 in. holes, in the brick to allow it to fit around the nuts/bolts.  The picture above shows the process using "Block 8" as an example; I numbered the blocks 2, 4, 6, 8, 10 and 12 from front to back on the left side, and 1, 3, 5, 7, 9 and 11 from front to back on the right side, to keep things in order when going to and from the garage.

The left and right sides were the most difficult parts of the firebrick installation, this was due predominantly to the number of projections into the firebox, including the grate rail (where the fire grate sits) and the nuts/bolts securing the grate rail and the nuts/bolts in the corners securing the front and back panels to the side panels.  Still, things went as well as could have reasonably been expected.  I am very happy with the outcome, and I expect the attention to detail to pay off in the life of the arch.Please "follow" the blog, or follow us on Facebook.

-- John, 02 Mar 2016

Easier said than done, the evaporator positioned on leveled blocks in the sugar house

1. Randall B. Heilegmann Ph D, “Chapter 7. Maple Syrup Production,” in North American Maple Syrup Producers Manual, ed. Melvin R. Koelling Ph D, et al. (Ohio State University Extension, 1996), 79-80.