Heat Relief Fan Sizing
What size should the HVAC heat relief hood be for a powder coat booth and oven?
Q. I’m designing the HVAC system for a new industrial shop with a powder coat booth and a powder coat oven. What size hood and cubic feet per minute (cfm) should I use for the heat-relief hood in front of the oven doors? The oven has one set of double doors (5 × 10 ft.) with total door area of 10 × 10 ft. Oven dimensions are 16 × 13.5 × 13 ft., and the burner is 1.5 million Btuh. The exhaust fan on top of the oven is 1,500 cfm, and the oven recirculating fan is 14,000 cfm. Using the ACGIH manual for drying oven ventilation, the cfm is about 13,000, which seems very high. The building height is about 44 ft. —D.L.
A. You will want the hood to extend at least 5 ft. out from the oven wall. Use a large-diameter stack (24" minimum) and run it as straight as possible up through the roof. Install a damper so you can adjust it. I would not use a fan unless your building has significant negative air pressure. It would be best to rely on a normal hot air updraft. If you must use a fan, 13,000 cfm would be a disaster. You would pull way too much air from the plant and the oven. I would suggest a maximum of 3,000 cfm.
RELATED CONTENT
-
Anodizing Vs. Powder Coat
I am an engineer on a large yacht build project and urgently need information and advice on choosing a finish for the aluminum deck plates in the engine room.
-
Preparation of Stainless Steel for Powder Coating
Should type 316 stainless steel castings be sandblasted before powder coating, or can they be chemically etched? Should the parts be pre-heated in an oven before coating?
-
Calculating Oven Heat Load Capacity
Please explain how to calculate the heat load capacity of a paint baking oven, using aluminum alloy wheels as an example.