Venting my crawl space

[gmacfarlane]

Now that I have my HRV balanced, I realize that there is no intake vent to expell stale air from my crawlspace. Looking at the vanEE installation manual, I have  what they call an exhaust ducted system where the HRV shares piping with my furnace. Can I simply cut in a port, say 4" round on the stale air side and if so, should it be close to the HRV or at the far end of the system. I am concerned I will have very little draw on the furthest duct from the HRV.