In some cases a desired constituent is not soluble in alcohol or water and must be extracted in a more exotic solvent like chloroform or ether. If that is the case, you will need one of the Professional units that seal up so solvent vapors don't escape. Ultimately, carbon dioxide is often the ideal solvent because it has different solvent properties at different pressures and leaves no traces or residues in the final product. Different herbs have varying sensitivities to heat. It is usually good to have some heat when processing herbs.
Moderation is the key.
Temperature ranges from 100-150 degrees Fahrenheit are usually ideal. All of Eden Labs products will operate in this temperature range. Many herbalists believe that herbs should be extracted at room temperature. If you want to follow this rule, a cold percolation unit, the Professional Round Bottom unit, or a mixing tank is the way to go. Solvents are distilled out under gentle heat or gentle heat and vacuum or just vacuum if no heat is desired.