|The secret to making maple syrup is heat, lots and lots of heat. The faster the sap is boiled down, the lighter the syrup. It takes 40 gallons (litres) of sap to make a single gallon (litre) of syrup, so a lot of water has to be removed. In most Rideau operations, a hot wood fire is still the prime heat source. In the commercial unit on the left and centre, primary evaporation is done with a fan assisted wood fire, while the final stage boiling is done with an oil fired burner. In the family run operation on the right, the entire process is done over a single wood fueled firebox.