First Run Maple Syrup, Vermont-Style, in My Homemade Evaporator

My first attempt at making maple syrup in my homemade maple evaporator was a success. Well, mostly successful. There was the incident with the pre-warming pot blowing into the warming pan, and the burnt foam stuck to the side of the finishing pan, and the… Hold on. Let’s get to the parts that went well first.

My homemade 55 gallon drum barrel evaporator worked pretty much exactly as I’d anticipated. My biggest worry was that flames would be licking up the sides of the steam table pans, due to the gaps around the edges where the pan sits in the barrel, thereby wasting heat. But I had a strong enough draw with my 4 foot chimney stack that the flames were all moving in an orderly fashion across the bottom of the pans and back toward the chimney. I was also pleasantly surprised by how little fuel I needed to burn to boil off my 25 gallons of sap. In all, I burned about 20 thigh-sized logs (for some reason a human thigh is the only thing I can think of for size comparison’s sake). I should note that I split the logs down considerably, to about forearm-sized, to get a hotter burn going. I attribute the fuel economy mostly to the extra steps I took to insulate the inside of the barrel.

sand in evaporator

My first step before building a fire in the maple evaporator was insulating it for fuel economy. I first poured about 4 shovel-fulls of sand in the bottom of the barrel.

maple syrup evaporator with log holder

Next I dropped in a log holder over the sand. This is a plain old log holder that you’d see in a standard fireplace. I picked this one up at Tractor Supply Co (on sale for $17. score.) It’s not an ideal size but it works well for the purpose of getting good airflow under the fire to help it burn hot.

maple sap arch with fire bricks

The next step is what I consider the most crucial in the fuel economy of my barrel evaporator. I stacked fire bricks on the sides of the barrel. These are plain ol’ 5″ x 8″ fire bricks that you can pick up at hardware stores. I debated buying these because they’re kind of expensive at $3 a pop (and you can see that I cheaped out and only bought 10 when I could have bought 15), but I’m really glad I went for it, because the return on investment was immediately apparent. At one point my wife came out to check on the progress of the boil and was standing about a foot away from the evaporator, holding her palms toward the barrel to warm them. “Huh,” she said. “I thought this thing would be a lot warmer.” That’s a good sign — it means all the heat is contained in the firebox and not dumping out the sides, wasted.

pouring sap in barrel evaporator

With the fire just getting going, it was sap time. Here’s me pouring fresh maple sap into the front pan. My daughter seems to be happy with my technique. The pans are full size steam table pans that you’d see in a hotel buffet. The blue container, of which I have four for sap collecting and storage, is a BPA-free water storage container that I purchased on Amazon.

With the fire picking up steam (pun intended), I filled both of the pans with fresh sap. At this point, I had one burning (pun intended again. sorry) question: which pan would burn hotter and boil sap quicker, the front or back? I assumed that the back would burn hotter because of the draw out the chimney, so I made a point to build the fire closer to the front pan, thinking that would even the heat spread.

After a half hour, the back pan was at a rolling boil. The front pan, however, was barely simmering. My question was answered. The back burns hotter. But now I had another question: which pan should I be using as the finishing pan and which as the warming pan? My first-time maple syrup making logic told me the front should be the finishing pan, and the back pan should be receiving all that fresh cold sap. About an hour into it, though, I changed my mind and used the back pan as the finishing tray. Looking back — it’s now 2 days later — I can’t recall why I made that game-time decision. I probably panicked in the heat (last pun. really) of the moment, thinking I’d made a huge mistake. But really, what’s the difference? No, I’m asking. What’s the difference between the two pans, and should I be using the front or back as the finishing pan? If you have insight, please chime in in the comments below.

barrel evaporator in action

Here is my barrel evaporator about 2 hours in to the boil. Notice the light brown scorch marks in the middle of the pans on their rear inside side. That is where the flames inside the barrel were super heating the pans. I didn’t think about this when I built my evaporator to allow the pans sit down, recessed, in the barrel. The burning got pretty serious later in the day as the level of the sap went down — mostly it was the foam getting charred as it tickled the sides of the pan. My syrup came out much darker than I expected this early in the season, and I’m fairly certain it was due to the burnt sugar from the sides of the pan. It doesn’t seem to have affected the taste, however, and frankly, who cares how dark the syrup is if you’re not selling it commercially? Get in my belly!

vermont maple syrup march 2014

The final product. 7 pints of syrup. I’m pretty sure I underboiled this batch. Yes, I know I should get a hydrometer and get an accurate determination for the syrup’s readiness — but it’s much more fun to guess at it. Then, you can brag to your friends and other syrup makers, “Hydroma-what? Nah, I just eyeball it. I can, ya know, just tell when it’s ready.” Way cooler that way.


5 thoughts on “First Run Maple Syrup, Vermont-Style, in My Homemade Evaporator

  1. Nice work on the arch. You must be in the banana belt of Vermont. I have a few taps in the yard (Middlesex) and haven’t seen a drop of sap yet. Last year by this time, I’d made 5 quarts.

    • Hey Tom,

      Well it looks like this weekend into next week is going to finally be in the 40s every day, so it should be flowing for ya. I made another 3/4 gallon this past weekend on 21 taps, but I’m thinking the next few weeks will be a much higher yield. How are you boiling your sap?

  2. I just watched your videos on this project. I’m not sure why the back pan is hotter, but so is mine. I built a 2 pan system out of concrete blocks. It fits 2 pans just like yours. I thinks I’m going to build a system like yours for it’s portability. Thanks

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