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A Homemade File Cabinet Sap Evaporator

We were in need of something more than just a turkey fryer to get our sap turned into syrup. The turkey fryer does indeed work well for making backyard maple syrup, and it is what we still use to finish our batches of maple syrup. Our syrup production has increased now, and with the amount of sap we are collecting, a beefed up sap evaporator was a must. Off to the local habitat for humanity restore I went with a brain full of ideas, on the hunt for this and that to build the backyard sap evaporator.

See the file cabinet backyard sap evaporator pan in action in this video:

I settled on using an old heavy duty file cabinet for the firebox. I’d seen videos of file cabinet sap evaporators before, so I had some ideas to work off of for this build. For evaporator pans, I decided on stainless steel steam tray pans. These are a pretty common item used in backyard syrup making.

Inside the firebox, 6 clay pots are used to elevate some old oven racks a few inches off the bottom of the file cabinet to allow air to move underneath the fire. Underneath the door, I cut a 2 inch by 14 inch hole to act as the fresh air intake. Alternatively, you could cut a hole and use a bathroom vent fan on a dimmer switch to provide fresh air into the firebox. For my unit, this wasn’t necessary.

The flue consists of about 3 feet of venting exiting the firebox at the top rear of the unit. Once I have the evaporator in place in our sugar shack, I will most likely extend the flue to something closer to 6 or 9 feet in height to create a better draft in the unit.

Using the file cabinet evaporator is simple. With the pans and heat shields removed from the top of the evaporator, fill the firebox with paper, kindling and some larger pieces of dry wood. We have a surplus of chopped and split softwood that we don’t burn in the house, so that’s our main fuel for the fire. Light the fire and allow it to start to burn from front to back. Insert your heat shields, place the evaporator pans on top and fill them with sap. As the sap begins to boil, laddle sap from the front tray into the back two trays where the evaporator is hottest. Keep refilling the warming tray with fresh sap and continue the process until you run out. It’s best to start with a minimum of 200 litres of sap in order to make it worth while for a full maple syrup boil.


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