Helpful Hints in determining what size evaporator you may need.
Generally, most people size an evaporator to be able to boil one gallon an hour for every 10 taps or spouts that
they have out. This is based on the idea that 1 tap will produce on average 1 gallon of sap a day (when it is
running) and most people don't want to cook for more than 10 hours a day. For example: If you have 80 taps in
your woods you should purchase an evaporator or pan that will cook off 8 gallons of sap an hour. On an average
production day you will then be done in 10 hours cooking time (8 gal./hr x 10 hrs. = 80 taps). If you wish to
get done in less time purchase a larger evaporator and if you have more time then money you can purchase a smaller
evaporator and just plan to cook longer. Keep in mind that some days you may get runs of up to 4 or 5 gallons
per tap. These days don't come along very often, but you should have a plan to be able to handle this extra flow
when it does happen, you don't want your sap to spoil.
Sap quality is an issue for making good quality maple syrup. If you are thinking "I will just hold my sap and cook it on a day when I have more time", you must be aware that the quality of your syrup will not be nearly as good as it would have been if you had boiled it down immediately. What if it runs again before you get to cooking? Then you will not only have a lot of sap to cook, but you could have a lot of pour quality syrup when your done. If the weather is cool storing sap is not as big of a problem, but the warmer the sap gets, the faster it will spoil. In general try not to hold sap for more than 24 hours and if you must hold it that long or longer, do your best to keep it cool.
Flat Pan Cooking
In choosing the size of your flat pan to cook with, here is an easy calculation. You can generally boil off
one gallon of sap an hour for every square foot of surface area on your pan. For Example: A 2 foot by 4 foot
pan will cook off about 8 gallons of sap an hour (2 ft. x 4 ft. = 8 gal./hr.). Using the above calculations
you can then determine that this size pan will be good for up to 80 taps. Keep in mind that the square foot
of surface area calculation only works if you are firing hard with good dry wood or oil. It also helps to have
a properly shaped fire box and enough draft to keep your fire burning strong and hot. Generally, you need twice
as tall a smoke stack as your pan is long. For example: If you have a 2 foot by 4 foot pan then you should have
an 8 foot tall smoke stack.
Evaporators with flue pans cook at the same speed as flat pan evaporators with the same surface area, but when you consider the extra surface area created by the flues (raised or dropped) you can boil much faster with less wood or oil. Below is a chart that shows evaporation rates for evaporators with flue pans (based on the 7 to 7 ½" flue depth).
|Evaporator Size||Flue Pan Size||Average Evaporation Rate in GPH (Evaporator)|
If you have any questions please feel free to ask.