Please help me figure out why this isn't working - I don't know what to try next.
This is my vent hood - an upside-down washtub. It has 8 inch vent pipes and the fan is on the other side of the wall. It's 24 inches above my table, 18 inches above my torch.
Incense test failed - the smoke just wafts about going here and there and eventually most of it goes up.
The fan is this one from grainger:
Blower,495 CFM,115 V
Shaded Pole Blower, Air Flow @ 0.000 Inch Static Pressure 495 CFM, Speed 1570 , Voltage Rating 115 Volts, Power Rating 225 Watts, Current Rating 3.25 Amps, Frequency 60/50 Hertz, Thermal Protection Auto, Wheel Diameter 6 1/4 Inches, Wheel Width 4 1/4 Inches, Air Flow @ 0.100 Inch Static Pressure 476 CFM
Grainger Item # 4C445
The fan box looks like this, except it has 3 extra 2.5 inch holes drilled in the bottom of it to provide air to the motor:
The make up air - door open or shut, same deal. I also have the vents in the wall above the table, behind the hood, I've tried them open and shut, doesn't seem to make a dif. We've gone over the whole system, it's all screwed and taped tight.
I tried adding some back and side baffles, no help. The fan seems to be exhausting strongly. I tried blocking part of the vent hole in the hood and it grabbed right on to the hard plastic sheet I had and held it up by itself.
I called grainger and the tech guy there suggested I change to 6 inch pipes. Dale says that info is incorrect.
I don't know what to look for next. Please, any ideas?
Thank you.