Exhausting into house?

[ItsAllOver]

So I've been contemplating my system, in which there's now a 1kW flowering room (4.5'x4.5'x7') that needs a 6" fan added to the already existing 4" one for the 600W veg room. I am exhausting the 4" fan into a 4" hole that belongs to a light fixture that I removed, and am unwilling to enlarge the hole or create a new one to vent to the attic with, which would otherwise be my initial choice. Winter is coming too, and it brings snow, which would melt on the roof from my exhaust, looking odd. So moving the vent would be good anyway.

The question:
Is it possible to exhaust my 1kW flowering room through the same doorway that leads to my grow room that I am bringing my air in from?

I'll be extending the insulated ducting to a bedroom across the hall, allowing it to benefit from the waste heat in the winter. So... the air coming out won't be going exactly to where most is coming in from, but pretty close.

What should I be thinking here? I'm not worried about the heat being an issue, because I'm pretty sure the cold weather and my 420 cfm fan will be enough to take care of that, based on my test today without plants. I'm just concerned that I won't be giving my plants enough CO2 this way, because no matter what, some air is certainly going to be recycled, which is probably not optimal with a 1kW flowering plants 600w of vegging plants in a room. They'll need all the CO2 they can get. I might be acting crazy though, to think that this room is even going to have much effect on ambient CO2 levels in the upper deck of the house...

I guess you could think of it like the relationship between a cabinet and its venti system in somebody's den or bedroom and my grow tent venting into my greater house area, since the exhaust is going back into the source area... Just a larger source area, sort of.

Anyway, what the deal, yo? Any input?
I would like to supplement CO2 but don't have the $. Anyway, I don't want to do it until I can get 100% sealed.

 

[PuReKnOwLeDgE]

Ambient temps play a large part of the temps inside your cab. I have vented in the same room before and you will notice a large increase in RH. Enough that your windows will be wet, which can also be an indicator. I don't recommend exhausting anywhere near your grow, exhaust is just that, exhaust. Get rid of it! Just make a larger hole and repair it when your done. It will PAY for itself. I always vented to my attic, and left window open in the summer, and closed in the winter. I still had snow on my roof. 3000 watts of light at that time. Make a hole, repair later, easy fix. Make better enviorment, grow better plants, get more yield.

 

[lloyd]

If you have plants in a sealed room with no outside air coming in your Co2 will be very Low. like 300ppm and lower. If you are bringing air in from one location and you want to vent it out into the same location this shouldnt be a problem I would just keep and eye on the recycled air coming in make sure it isnt the same low ass co2 air your putting out. in a normal house the co2 is around 600-1000. good luck

 

[ItsAllOver]

Yea I hear that analysis. The hole wouldn't really be fixable, but it could be covered up in the sense that the light fixture that goes over it is larger than the hole. If the landlord ever looks there, maybe removes the fixture to paint, it'll be obvious that mods were made. I'm not so sure on the snow thing for a couple reasons, and it might just come down to redoing the ducting in this less desirable way during times of snow if it's looking sketchy.

Fuck it, I think I'll just cut the hole tomorrow.

 

[billy_big_bud!]

heat from that amount of light wouldnt melt the snow on your roof imho. upwards of 4 or 5 maybe but one light, i think you would be ok.

 

[FrankRizzo]

heat from that amount of light wouldnt melt the snow on your roof imho. upwards of 4 or 5 maybe but one light, i think you would be ok.

I have to agree. I have a 1500w heater that can't keep a cold room very warm at all. And while I'm sure there are differences between a bulb and a heater I have to believe the heater would be more efficient at heating. Also depends on your specific roof, but I have a feeling you would be fine.

 

[ItsAllOver]

Yep. Honestly this is my first run with a 1k bulb, and I didn't know what to expect. I ran it last night with the exhaust going into the bedroom across the hall, and the grow tent stayed at 80 (all night, I woke up a couple times to check it. It wasn't creeping up) which is fine by me and the ambient house temp was up at 72 from 68. Ambient house humidity never exceeded 55-57% which is ok for now. I had my hygrometer outside the tent but I'll put it inside tonight and check. It could well be lower in there because of the air movement, correct? I'm shooting for 45% during late flowering. Nothing a dehumi can't fix if necessary (I hope it's not!) I've never had problems with PM anyway. I use good air intake filters, move lots of air, all seems fine. Just an outdoor issue, and it sure is an issue out there.

Also, the temp of the air exiting the ducting was not too high at all, so I wonder whether or not it would melt anything. Sort of doubt it. However, I'm still not so sure about my particular roof situation (location of exhaust in relation to roof shape, material)

Now I'm just trying to decide if I like the supplemental heat, because this is an old, leaky, uninsulated house. So I thought why not, ya know?

I am just not 100% happy about cutting the hole in the ceiling. I want to move from this house to something more suited to my purposes asap, but this is my option for right now. The repair would be obvious if a particular fixture was ever removed to reveal the ceiling, and I don't want my future security to be compromised from something I did long before. (I tend to go too far with security issues)

Anyway, I don't see any harm right now from running it as is and taking some time to decide.

What do you folks think about ambient CO2 depletion, though? I still have my 4" fan running into the attic, meaning there is surely outdoor air is being forced into the house that way, and some would make its way to my 1k tent.

 

[Haps]

I exhaust into my veg room and let it flow back into the house, new air cycles into the bloom, plenty of normal co2, no worries. And my heat bills are way low, I like that.
H

 

[ItsAllOver]

Thanks Haps.
I'm going to give it a shot. I imagine that with how leaky my house is, there will be plenty of CO2 exchange, so as long as I can keep the temps and RH within range, it should work fine and save me some cash on heating this winter. Then when I get a couple crops out with this setup I'll get a new house and be happier!