Gravity Convection Air is circulated by natural convection. Since hot air moves up, a gentle movement keeps temperatures fairly uniform within a chamber and quite uniform in any particular location.
Mechanical Convection is a gravity convection oven assisted by a re-circulating fan in a working chamber.
Forced Convection Ovens
These ovens include a fan that provides forced air circulation through the heating chamber. This system gives very rapid heat up and recovery times, combined with particularly low temperature variations within the working chamber. Adjustable vents and semi-forced exhaust make it a good sample-drying oven.The drawings below illustrate three forced convection systems.
Forced Exhaust Ovens
In these ovens, air is forced through the working chamber by a fan, and dispersed through an adjustable vent. This type of oven is particularly useful in applications where the heating process produces gases or fumes that need to be quickly and continuously removed from the working chamber. All of the forced air ovens exhaust at a greater rate than a convection oven. However, much larger forced exhaust rates can be achieved by including an air inlet and an adjustable outlet.
This modification costs an additional $100 and is only possible with forced convection ovens.
Side Draught Ovens
These ovens have air circulation from one side to the other i.e. left to right. Rapid heat up and recovery time make this type of oven ideal for preheating plastic sheets (hospitals, etc.) or any work where flat sheets or trays are used. Even air flow and heating is ensured.