Two 45° Elbows are necessary when a bend is needed on the venting of your Envirolet® Waterless Self-Contained System.
Ideally, there should be no bends in the venting system. A straight vent is the most efficient. Non-Electric Systems should not have any bends. When considering adding bends to your vent, consider the Envirolet® Turbo Fan, which can increase evaporation in vents with bends.
There should never be a 90° angle in any vent configuration.