Quote from: wndsnb on Today at 04:46:34 PM

Just did a search for flexible duct specs and this was what came up (from Thermaflex), you may be able to find similar specs for the exact duct you're looking at with enough internet searching...

For a straight run of 10" duct at 1000cfm (which includes safety factor since the fans on the miner max out at 500cfm each at 0 static pressure), it looks like about 1"H2O per 100'. I assume you'll have some bends in there, so the drop would be higher. Maybe just give yourself a factor of 2 more safety factor. Or click on the image below to open the pdf where they go into depth about how to calculate equivalent lengths with bends.

This is awesome info - thank you.. For the bend, I can shorten that exhaust duct, just needed it pointed upwards towards the exhaust fan. I have a ~2500 cfm exhaust on the roof, may add another, enough ventilation, so not worried about the negative pressure.