Help - spray booth fan - how much CFM?

[Kenny King]

I'm trying to determine how big of a fan I need for a spray booth. This would be a wall mounted fan mounted to a window opening - just the fan, no window.

I'm planning on spraying water based finishes.

I saw one example where a guy used a 2200 CFM axial explosion proof fan. This seems like a good solution.

Any folks have any idea of what ballpark CFM I should be looking at. Will 3500 CFM be too powerful? i mean even with another window open, i don't want to create a vacuum and start pulling air back in through the chimneys for my water heater and furnace.

- Ken

[Matt Meiser]

Personally I don't think you could reasonably go too powerful, though I suppose if you had a wind tunnel fan...

I have the setup you are looking for with something like a 3500 CFM fan. I don't think it causes my furnace to backdraft because my furnace has a forced draft and shuts down if there isn't correct flow. However, there is a DEFINITE difference in fan sound and air flow between having a window open a couple inches and having all the doors and windows closed. I have 4 furnace air filters mounted in front of the fan to collect overspray and that setup is working well for me.