Purpose of a fan

[joebiggsly]

What exactly is the purpose of the fan? As I understand, it is used to homogenize the air, that is, ensure the air is the same temp. throughout the oven by "mixing" it. Do you actually want a draft? It seems to me that a draft would remove heat from the oven and cause a "stream" of cooler air and cause hot spots. I ask because I am trying to choose a fan, and the purpose will dictate which fan I choose. Thanks in advance.

[FigureLLC]

you're right about the mixing part. ideally you want the fan pulling air from the top of the oven and discharging it at the bottom. too much air movement is no good if you're blowing powder off the parts or if it's enough air to get your parts swinging and bouncing off each other. too much air movement won't create hot spots, though.

what size is your oven?

[philipd]

Another question: should the fan draw in cooler outside air or should it just recirculate the air in the oven?

[SCOTTRODS]

Originally Posted by philipd

Another question: should the fan draw in cooler outside air or should it just recirculate the air in the oven?

Re-circulate only.

[FigureLLC]

yup, recirc. your oven should be vented, though. expanding air in the oven is coming out somewhere, which will be more than likely around the door seal if you don't vent it, and it'll leave ugly smoke marks around the door.