Can't brother as I am using co2. Thought about it... but the decision to use co2 won...LOL. Also using the adjust a wings. I was just getting the jitters as it is getting close to running time.
Weeeellll... that ain't necessarily so...
If you're running tanks, there's no worries at all; run it right into the house. If you're running a burner for CO2, then the *possibility* exists that you'll have CO buildup somehow. This is a much bigger possibility with natural gas than propane. BUT in either case, you need to go to Home DePot and get a $40 carbon monoxide detector (a good one with a digital ppm readout!) no matter what- even if you just run a standard gas furnace to heat your home. If you're running a burner you MUST get one of these for your safety and that of the plants as CO isn't good for them, either.
For the air to get through your house, you'll need someplace to exhaust it from your place; choose some low spot, like a basement window or a cat door and place an exhaust fan there. This will both suck cold air out and help encourage the air from the hoods to pass through your home, warming it. To keep cold air from entering while the fan is off (like dark cycle), use a backdraft damper or just a flap over the opening to keep it closed. By the way, if the CO2 tank you may be running decides to suddenly empty, this low exit will suck the gas out of the house before it can build to toxic levels. Once it cools to room temprature, CO2 is heavier than air and will sink to the floor, like butane. CO2 is NOT flammable, just in case someone wondered!
Now, once you have a detector, you're clear to route air from outside through your hoods and into the house. This air is meant to remain separate from grow room air and thus should not pick up more than a tiny amount of air from the room on the way through. If you push the air through your ducts with a fan upstream of the hoods, you'll have no issue at all, but this will substantially reduce the efficiency of the hood cooling system.
One more issue to think about when routing outside air through your hoods; if your climate drops below freezing, you're likely to overcool your bulbs, which leads to them running too cool and changing their spectrum. To avoid this, use a thermostat and place the sensor in the ducting just downstream of the first hood in your chain. Set it to 70 degrees, and whenever the temp falls below that it will shut off, thereby allowing the bulb to stay warm. Only one thermostat is needed per circuit; you can run all your hood fans right through the thermostat.