A Question About Exhausting via Furnace Ducts

Just wondering... Would running a 6in carbon exhaust from the G-room into a heat duct while the furnace is idle cause issues?
(pilot light, humidity, etc.)

The idea is to push warm air down to the basement which acts as heat sync and maybe gets some airflow down there too. Would this work? Or would the air just be trapped in the furnace and kinda seep out?

In the winter, I would be pushing the air under the door crack to be up-taken by a large air intake grid adjacent the room and boost the furnace's efficancy. In the summer, the furnace isn't sucking any air in, so it would just cook the upper floor of the house.

I have considered piping the exhaust out the window, however it's a densely populated urban area, and I have concerns about cops or competitive neighbor-growers hearing that soothing whorl of air, or smelling that dank herb in bloom, then barging in to crush my life lol. Also, i have the window in stealth black out mode, so high airflow there would create a lot of movement of the coverings.

Any insight or experience here would be really helpful guys

That is a very dangerous proposition, it could certainly cause some serious issues. When the furnace comes on you could get carbon monoxide and other nasties backflowing to your grow space.

If you want to exhaust out the window there are baffles you can get that significantly reduce the noise, much safer in my opinion.

Hmmn ok, dont want that. Thanx fxbane, what are these baffles like? I know i can build an insulated box for the fan vibration, but i remember from the 10" days that distinct whosh of air. Maybe it wont be such an issue now with a smaller fan, haven't set it up yet. It's also a good 15+feet up from ground level so maybe no one will notice... Also thought of maybe putting in a normal window fan, and taping the ducting to it just to normalize the scene from outside... would also be good cover for sound methinks.

I've never used one personally but I have helped a friend set a grow up where they bought one and it did make a drastic difference. I had a check on ebay for one, found one here. I'm due an upgrade in extraction soon I will probably add one for peace of mind, much smaller of course. I can tolerate the noise of a 5" at the minute and I'm pretty sure nobody can hear me 15ft away. Those window fans aren't that common here so I can't really say if it is good cover or not, maybe someone can vouch for it?

Response about the carbon monoxide is 100% incorrect that person does not have the knowledge of a heating system to be giving any advice. Assuming you have a forced hot air furnace with a central return I cannot see why that would be a problem but it's not gonna blow out in your basement. It will more than likely take a path of least resistance in the duct work and blow out of the nearest vent that you hook up to like if there's one in the next room.


And as far as carbon monoxide that's bs. combustion air is pulled into a furnace with whatever fuel your using and exhausted through your flue piping to a chImney or if it's a newer furnace out the side of your house. It is completely separate air than what is in your duct work. Air that heats your house is pulled through either a central return or individual returns passed through the heat exchanger in your furnace and back out through the supply vents. The only possible way you would mix carbon monoxide would be if you had a cracked heat exchanger and if you did you would be leaking carbon monoxide into your house everytime your furnace ran.

Doing what your suggesting would be fine but I don't think it will have the result your looking for.

^ he is right. The real problem with using existing ductwork is when you try and tap into the exhaust vent on your furnace or water heater

Granted, I have no HVAC experience at all and should probably have clarified that. I am merely parroting information told to me when I asked a heating engineer pretty much the same question. Got a speech about the pipes only being rated for a certain airflow and that adding an exhaust fan could cause a backflow of carbon monoxide to my grow. Since I didn't fancy poisoning myself and my family it kind of seemed like important information at the time. Thanks for the education.

No problem sorry If i came off ass a dick I was a little fired up last night lol