i just recently upgraded to a vented hood so I can run 400-600 watt hps. Problem is, the hood has 6" ports. I only have a 4" fan and filter and don't want to invest in a 6" combo yet. I put reducers on both sides of the hood and ran 4" ducting to the fan and filter. Temps are ok @ 450 watts but just a tad high @ 600 watts. My question is, if I put the reducers on the fan and filter instead and ran 6" duct, do you think that would allow more air flow and help temps stay down a little more?
I understand that but I was wondering if the 6" would create less resistance in the line itself allowing a slight bit more air to be pulled through.
A larger diameter duct would make the fan less effective, as the area in which the fan has to move the air has increased so the "power" of the fan is more spread out meaning a slower turn over even if you have less surface resistance.