How to Size an Evaporator

How to Size an Evaporator

Transforming maple sap to syrup is a straightforward process. You simply boil it to evaporate liquid, leaving the thick syrup behind.

An evaporator is what you use to boil the sap. Simple, right? Actually, selecting an evaporator can be quite complex. You need to consider a wide range of factors including:
  • Whether you are using wood, oil or propane as a heat source
  • The number of taps you have now and amount of sap you collect
  • Whether you plan to add more taps in the future
  • How long you want to boil
  • The size of your sugarhouse

When we advise customers, the very first question we ask is about the heat source they will be using. Evaporators that burn wood are less efficient – but also less costly – than ones that operate on oil or propane.

Armed with this information, we consider size next. How much sap do you plan to boil and how long are you willing to devote to the evaporation process? The larger the pan, the more surface area and therefore the more gallons per hour that may be evaporated.

This chart can help give you a sense of evaporation rates:

Evaporator Size                  Evaporator Gal/hour
12" x 20"                                            1
19" x 36"                                            3
24" x 33"                                            5
24" x 48"                                          8-10

We generally recommend a three- to five-hour boil time for evaporators. So let’s say you get about 1 gallon of sap per tap and have 30 taps.

Here’s how we might calculate a starting size:

  • 10 taps x 1 gallon/tap= 30 gallons
  • Time available to boil sap = 4 hours
  • Evaporating capacity needed = 30 gallons/4 hours = 7.5 gallons/hour
  • A 24” x 48” evaporator might be the best choice

We stock evaporators  in all sizes from a 2’ x 33” evaporator up to a 7’ x 18’. These evaporators can boil off a few gallons per hour or as many as 1,000 gallons per hour of sap. It is also important to consider your future plans. If you plan to expand, be sure to choose an evaporator that can grow with you, or be able to accommodate add-ons, so you don’t have to replace the evaporator when you add more taps.

Whether you have 10 taps or 100,000, we will work with you to help you find the right evaporator(s) for your needs. We try to keep the smaller evaporators listed on our website in stock, and most of them are set up in our showroom. The larger evaporators are usually a special order since they are often customized with options and features that you select.
Previous article Getting Started as a Backyard Maple Syrup Producer