I just bought 2 of these 600CFM inline fans to move air from the top of my paint booth in my garage, through two home furnace filters to stop any particles than outside. My old ones were starting to get old and clogged up, I guess I got the wrong CFM as last time and my new ones are blowing too fast. I unfortunately cannot return them
Is there a way to run them at a slower speed? They are 110V
These types of fan are normally speed controllable. There are different types of controller.
The ones I've seen fitted before now are normally similar to a dimmer switch or there are some that have 5 steps slow to fast.
Stand alone speed controllers however can often cost as much or more than the fan itself.
A cheaper alternative might be to install a blast gate or single blade damper to restrict the airflow.
It could very well be if your fan doesn't use a starting capacitor.
You could even wire an E27 socket (or similar) in series with the Line and just stick a incandecent bulb in there that'll limit the current to the motor enough to slow it down to your liking. Also it'll give you some light.
I doubt you care, but there are very specific code requirements for wiring in paint booths.
Just as an example, there needs to be an interlock between the spraying equipment and the ventilation system.
Good luck regardless.