This picture guide goes through the steps I take to boil the sap for making maple syrup. This is the second step in the process of making maple syrup, after collecting the sap, but before the final finishing boil.


This is part 2 of a 3 part series on how to make your own maple syrup. These are the links to the other articles in this series:

What I Use:

How to Boil Maple Sap for Syrup

The principle of boiling down your sap is really easy. You basically want to boil off the water, so that you are left with the highly concentrated sugar-water (syrup). Typical ratios of sap to syrup run anywhere from 20:1 to 40:1, depending on the sugar content of your sap. Sugar maple trees have the highest sugar content, so often the ratio of sap to syrup for a sugar maple is on the order of 32:1 or so, at least in my experience. If you don’t mind ‘watery’ syrup, then you can get away with less boiling, so you end up with a higher yield, like 20:1.

Steps for Boiling Sap

You can get all scientific about it if you want, but I am going to make some recommendations here for you. This will get you in the right ballpark for getting started. You will end up with some really tasty maple syrup, and as you go along and gain experience, you may decide you want to tweak the process to your liking.



Alright, these are the steps for boiling your maple sap:

  1. Set up your turkey fryer in a safe place where it won’t start surrounding brush on fire.
  2. Put 5 gallons of sap into your boiling pot and start the fryer.
  3. Set it at a medium heat and wait for it to start boiling.
  4. Once the sap starts to boil, you may need to adjust the heat slightly so that it keeps a nice rolling boil. If it is too hot, it will start to boil over. If it is too low, you won’t see bubbles coming up.
  5. Continue to boil down the sap until you have about 1.5″ to 2″ of sap in the bottom of your kettle. This will take about 4-5 hours.
  6. This will get your sap to about the 10:1 ratio.

Here, the sap has been boiling for about 1 hour.



In the following picture, the sap is nearly done boiling outside, notice the rich dark color of the sap. Soon, we will turn off the burning and bring the sap inside for the final boiling.



I recommend doing the ‘finishing boil’ on the stove inside your house so that you can keep a closer eye on it as well as to monitor the temperature more closely.

A description of the finishing boil will be given in the next article.

Improved Design

One minor problem with the method described above is that if you are boiling on a windy day, the wind disperses the heat rather quickly, and you have to run the fryer at a higher temperature. It can also add up to an hour of boiling time, so it ends up taking more propane.

An additional consideration is that you have 5 gallons of boiling hot sap propped up on these rickety fryer legs. If you have kids around, for example throwing a ball around, you may be a bit nervous about having them anywhere near this thing in case they should knock it over and get burnt. I had the same thoughts…

Luckily my uncle came across a great idea (not sure where he got this idea, wish I could give credit to the original inventor!): put the whole thing into a 55 gallon drum. I must admit a was a bit skeptical at first, but after he gave me one to try out, I am completely convinced. This thing is awesome!



There is a larger hole at the bottom for the gas line to run through.



Also, there are about 6-8 small holes drilled near the bottom to allow for air to enter in the bottom of the drum.



This makes it so that the whole boiling apparatus is contained. The area where the flame is, is completely sheltered from the blowing wind. Also if someone accidentally bumps into it, they do not get doused in boiling hot sap.





The outside of the drum also stays relatively cool. You can put your bare hand on the outside of the drum while the sap is boiling, and while it is pretty warm, it won’t burn you immediately. I can hold my hand on there for several seconds before it starts to get uncomfortably hot.



A Few Words On Propane

Refill vs Exchange

The 20 lb propane tanks I use hold about 4.6 gallons of propane. I recommend that you take them somewhere to be re-filled, as opposed to exchanging the cylinders – and here’s why. When you exchange the cylinder, the tank you are exchanging for is not filled all the way full and typically only holds about 3.5 gallons of propane.

I usually refill the tanks at Tractor Supply, where currently the price is $2.19/gallon. So to fill one of these tanks is about $10.

How Long Does One Tank Last?

The tank will usually burn for about 20 hours total. This is enough to boil down about 4 batches of sap (5-gallons each).

Making Maple Syrup – Part 1 – How to Tap Maple Trees for Sap

Making Maple Syrup – Part 2 – How to Boil Maple Sap

Making Maple Syrup – Part 3 – How to Perfect the Finishing Boil