One question we get a lot from people considering the purchase of a rotary evaporator is about the condensers. Specifically, what is the different between a diagonal and vertical coiled condenser and when would each be most appropriate?
The answer is surprisingly simple: It's just a matter of space.
Vertical and diagonal coiled condensers from a given manufacturer almost always have the same condenser design, differing only in its orientation relative to the rotavap and other glassware. Therefore, they have the same cooling surface and power.
If you'll be using the rotory evaporator under a low shelf or cabinet, you may want to use the diagonal condenser. If you want to conserve benchtop area, use a vertical condenser.
It's that simple.
The LabTech EV311Advanced, shown with both vertical (lower left) and diagonal (top right) coiled condensers.