How do you make maple syrup evaporator?

Making your own maple syrup evaporator is a fun and rewarding project for anyone who enjoys working with wood and making things from scratch. With some basic woodworking skills and the right materials and tools, you can build an evaporator that will efficiently boil down maple sap into delicious syrup.

What is a maple syrup evaporator?

A maple syrup evaporator is a device used to boil down or evaporate maple sap into maple syrup. It consists of a pan or pans to hold the sap, a heat source to boil the sap, and a holding tank to collect the finished syrup. Commercial evaporators are large and elaborate, but small backyard evaporators can be made from simple materials like galvanized stock tanks and firewood.

Why make your own?

Building your own maple syrup evaporator allows you to customize the design to your space and needs. You can make it as simple or complex as you like. It also gives you more control over the syrup making process. Store-bought evaporators can be expensive, so if you have access to maple trees, making your own is a great way to save money. It’s also a fun project that provides a sense of satisfaction.

Planning Your Maple Syrup Evaporator

Before starting construction, you’ll need to make some design decisions and gather supplies. Here are the key considerations:

Evaporator style

The two main styles of maple syrup evaporators are flat pans and flue pans.

Flat pans are wide, shallow pans that heat sap over an external fire. The shallow depth allows for quick evaporation. These are the simplest type to construct out of materials like cinder blocks and galvanized steel.

Flue pans have partitions that allow hot gases from an external firebox to pass through channels under the sap pan. This gives greater surface area contact for efficient evaporation. Flue pans take more time and skill to construct but are a common design.

Pan material

Common materials for evaporator pans include:

– Galvanized steel – Durable and inexpensive but can affect syrup flavor.
– Stainless steel – More expensive but won’t affect flavor. Best for food-grade syrup.
– Aluminum – Affordable and lightweight. Can be shaped into flue pans easily.
– Copper – Excellent heat conductivity. Usually only used for smaller, specialty pans.


Consider how much sap you’ll be boiling at one time. Backyard evaporators are typically in the range of 16-48 square feet of pan surface area. Make sure your heat source will be sufficient for the size of the pan.

Heat source

Options for heating include:

– Wood fire – Traditional and inexpensive but requires lots of fuel and stirring of the pan.
– Propane burner – Easier to control than wood but you’ll need a large tank or consistent fuel supply.
– Wood-fired arch – Channels heat over the pan and is extremely efficient. More complex to build.

Other design choices

– Will you use a holding tank for finished syrup? This allows continuous boiling.
– What style valve will you use for drawing off syrup? Ball valves work well.
– How much insulation will you use around the pan? This improves efficiency.
– What materials will you use for the frame and housing? Treated lumber works well.

Tools and materials

You’ll likely need:

– Sawhorses and lumber for the frame
– Metal for the pans
– Drill and hardware for assembly
– Cutting tools like a jigsaw to shape pans
– Welder if welding pans
– Food-grade paint or sealant
– Piping, valves, and fittings
– Insulation like fiberglass batting
– Shovel and metals stakes if using a wood fire

Constructing a Simple Flat Pan Evaporator

If you’re a beginner, starting with a simple single-pan flat evaporator is recommended. Here is an overview of how to construct one:

1. Make the frame

Construct a sturdy frame using 2×4 or 2×6 lumber to elevate the pan about 3-4 feet off the ground. Cut two longer beams as the front and back frame. Then cut cross supports that go under the pan every 2 feet or so. Use screws or nails to assemble the frame.

2. Cut and shape the pan

Use jigsaw or angle grinder to cut steel or galvanized stock tank to desired shape and size. Weld or rivet corners together to make a square pan with 3-6 inch sides. Cut a drain hole with valve in one corner.

3. Install the pan

Set the pan on the frame and attach securely using angles brackets and screws. Drill holes as needed. Caulk any gaps with high-temp silicone. Paint the inside of the pan with food-grade sealant.

4. Add piping and valve

Install a pipe to the drain hole. Attach a ball valve or spigot to control syrup flow. Run piping along frame and install a second valve on end over a collecting container.

5. Insulate underneath

Cut rigid insulation board to fit under the pan. Secure it tightly to the frame. The insulation greatly improves efficiency.

6. Set up the fire box area

In front of the frame, establish a fire pit for the evaporator pan to sit over. Line it with fire bricks or stones. Have shovel and poker ready to manage the fire. The flames should directly contact the bottom of the pan.

7. Make a sap collection box

Construct a holding box with a spout above the pan to hold sap. Make it out of wood or metal with an open top to easily pour in sap. This allows you to continually add sap while boiling.

Operating Your Maple Syrup Evaporator

Once your evaporator is constructed, you’re ready to start boiling. Here are some tips for operation:

Preparing the sap

It’s best to pre-filter your sap through cheesecloth or a fine screen to remove debris that could burn on the pan. Pour the sap into the holding box before starting the fire.

Starting the fire

Use dry kindling and wood to start a robust fire under the pan. Hardwoods like maple, oak, or ash work well. The sap should reach a rolling boil as quickly as possible.

Adding more sap

Carefully pour sap from the holding tank into the boiling pan as the level drops. Try to maintain at least 2 inches depth. Add more wood to the fire as needed to keep a vigorous boil.

Controlling the boil

Boil the sap down, adjusting the fire to maintain a steady boil. Use a poker to prevent ashes from accumulating on the pan bottom. Scrape the pan sides with a spatula to prevent sugar crystals from forming.

Checking sap density

As water evaporates, the sugar concentration rises. Use a hydrometer to monitor density and boil until it reaches 66-68% sugar content.

Drawing off syrup

When the desired density is reached, open the valve to draw off finished syrup into your collection container. Let it settle for a few minutes then decant into bottles.

Storing syrup

While still hot, filter the syrup through a felt or paper filter to remove sugar crystals (“sugar sand”). Store the syrup bottles in a cool, dark place or refrigerate.

Tips for the Best Results

Here are some additional pointers to help you make the finest maple syrup:

– Keep an eye on sap levels and don’t let the pan boil dry. This can damage the pan.

– Draw off and replace sap every few hours to prevent caramelization on the pan.

– Use sap from the first maple flow for lighter syrup. Later flows yield darker syrup.

– Boil the sap as quickly as possible for optimal flavor. Don’t let it sit around.

– Keep your fire hot. Simmering rather than boiling leads to off flavors.

– Let your finished syrup sit overnight. This improves thickness and crystallization.

– Consider accessories like steam hoods to increase efficiency.

– Experiment with flavoring additions like vanilla or cinnamon.

Safety Tips

Boiling sap on an outdoor evaporator requires caution. Follow these tips to stay safe:

– Have a fire extinguisher on hand in case of accidents.

– Wear heat-resistant gloves when handling the hot pan.

– Don’t leave the fire unattended and make sure it’s fully extinguished.

– Allow the pan to fully cool before handling to avoid burns.

– Keep children and pets away from the hot evaporator.

– Exercise caution when using propane and handling hot liquid.

– Make sure smoke and steam don’t blow toward your house or barn.


Constructing your own maple syrup evaporator is a fun and rewarding DIY project. With some simple materials, woodworking skills, and a heat source, you can have a productive system boiling sap into sweet maple goodness. Carefully follow plans for a safe, efficient design. The process allows you to make maple syrup from start to finish with ingredients from your own trees. Enjoy the delicious homemade results flowing from your evaporator!

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