new 4k W setup need help with ventilation in extreme climate

Ok here's the deal, I'm finishing my last crop in my current house. I set it up a year ago with some basic knowledge. The room 12x12 is built in my basement with fire/sound insulation. I have 2 can 75 filters in the room mounted to the ceiling. One in each corner, attached to a 6" max fan pulling air through the filter and pushing it through the lights into Y and into the homes ventilation system to heat the house. I have a 12000btu window ac venting into the basement and 2 ducts going into the room from the central a/c. The problem with this setup besides terrible airflow is that without the central ac on I can't get the room under 80. Now that winter is coming I can't run my central ac and the heat from the window ac is heating up my basement and basically pulling it back into the room and throughout the house.

I'm working on setting up my next place but I want to figure out how I'm gonna run the ventilation to accommodate 30c summers and -30c winters. Heres where I'm stuck.

I'm going to build another room in the basement 12x12 or maybe 12x15.

Option 1 - pull freezing cold air from directly outside to cool the lights and exhaust into the home ventilation to heat the home. Have the fans on a controller . I see condensation and being too cold with the lights off as my main two issues here.

Option 2 - pull air from outside into the basement. Maybe build a small room to pull outside air in then pull air from that room into the grow room through the lights then exhaust into the homes ventilation.

I'm leaning towards option 2 but with either one I need to get air in cuz i dont wanna use c02. How could I do this ? Carbon filter pulling air out of the room and through the house then use the small room as a passive intake? Or could I do the same thing just scrubbing the room would that work.

Anyone have any suggestions, input, ideas or something I'm not thinking of let me know Id appreciate any help I could get.

Use a day night temperature controller and a dust shroom and intake cold air as required to maintain temps.

You could also pull a negative pressure on the hoods and vent that heat upstairs when lights are on.

I would go with the lung room option, I notice my rh rises when the temp outside drops it's takes longer for my greenhouse to turn on the high temp vent. So my rh rises because of it not a problem if you have a dehuey however. I think the problem of fresh air will become worse as the temp drops. And with less air circulation co2 will be low. I have a co2 burner but you say you don't want to use one.

Anyways look up lung room.. Might be helpful.

Basically the only way you couldn't do it is run outside air in winter directly to air cooled reflectors.

Still, temp control and humidity will be a bit tricky but doable.

Remember, there's more CO2 inside your home than outside. I did a few experiments with a CO2 meter in homes, and no outside air intake grows, and the CO2 levels were actually relatively high.

- Jiji

jijiandfarmgang said:

Basically the only way you couldn't do it is run outside air in winter directly to air cooled reflectors.

Still, temp control and humidity will be a bit tricky but doable.

Remember, there's more CO2 inside your home than outside. I did a few experiments with a CO2 meter in homes, and no outside air intake grows, and the CO2 levels were actually relatively high.

- Jiji

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I would pull air from inside the house if I could vent it outside. If i pull from inside ill just be recirculating hot air from the return duct. If i vent out the stack that much hot air pushing in the winter stands out like a sore thumb. Around here that's how they find which houses to rob

Update
Just in the process of putting the room together. I built a 10x15 room in the basement with another 8x3 room off of it.(lung room) In the 8x3 I installed a 6" intake vent from outside.(haven't determined if I'll need an inline fan on this yet or if a passive intake will suffice)
In the 10x15 I white polyd everything ( floors, walls, ceiling) mesaused out the lights for a 5x5 footprint and hung 4 1000 watts air cooled shades. I'll see how I can dial it in before I look at adding another 2. Idealy I would like this to be able to run all winter without needing to add a/c.
I cut 2 6" holes in the wall from the 10x15 room to the 8x3 and ran ducting through each row to the end of the room. hooked up the ducting to a 6" inline fan pulling the air from the 8x3 room through the hoods and pushing it into the return air duct located in an ajacent room. As for smell I have 2 carbon filters hung on the ceiling at each end of the room one scrubbing and another pulling air into the return duct.

I'm kinda stuck on the intake part because I'll be pulling air out with one carbon filter and 6" fan should i have some air coming in to replace that?Should I put one or 2 more 6" holes to the 8x3 room to pull that cold air in? And this is where I'm thinking I might need that inline fan on the intake if I'll be pulling air out of that room with 3 fans would it be able to keep up?
Can anyone shed some light on this aspect for me ?

@SnapsProvolone suggested a day night temperature controller . would you hook one up to each fan or just use one?

Thanks I appreciate any and all help/advice!

modene said:

I would pull air from inside the house if I could vent it outside. If i pull from inside ill just be recirculating hot air from the return duct. If i vent out the stack that much hot air pushing in the winter stands out like a sore thumb. Around here that's how they find which houses to rob

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You don't have to vent outside. Not easy, but it can be done. 4000 watts is not going to heat a whole house in winter.

Its hard to picture your new design. Return air duct, as in heat vent?

1 6 inch fan for 4000 watts with carbon filters is not enough.

I would think you wouldn't need outside air.

- Jiji

jijiandfarmgang said:

You don't have to vent outside. Not easy, but it can be done. 4000 watts is not going to heat a whole house in winter.

Its hard to picture your new design. Return air duct, as in heat vent?

1 6 inch fan for 4000 watts with carbon filters is not enough.

I would think you wouldn't need outside air.

- Jiji

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Depends on the size of the house. Yes the hot/cold air return duct that runs through the homes ventilation. I've always set it up this way and never had problems . I do it this way to minimize my heat signature but in the summer it has been a very taxed system the central a/c just fights the lights.

I dont have one 6 inch fan for 4000 watts .. I have 2 runs of 2000 watt each hooked up to their own 6" inline fan.

Ok, its clearer now.

If your gonna bring in outside air, your going to need to control it. Because its most definitely not a constant.

A thermostatically controlled powered damper, or fan is what you want.

You will run into a condensation issues. If you had one vent near the window or near ceiling, condensation will build up above it and mold in no time. Maybe if you can run insulated duct to center of lung room and if its turbulent you should be ok. Not sure on that one.


- Jiji

jijiandfarmgang said:

Ok, its clearer now.

If your gonna bring in outside air, your going to need to control it. Because its most definitely not a constant.

A thermostatically controlled powered damper, or fan is what you want.

You will run into a condensation issues. If you had one vent near the window or near ceiling, condensation will build up above it and mold in no time. Maybe if you can run insulated duct to center of lung room and if its turbulent you should be ok. Not sure on that one.


- Jiji

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You mean run insulated ducting from outside into the lung room? Do you think I would need an inline fan to pull the air in or should I have enough negative pressure from the 2 fans pulling air for the lights so it works as a passive intake?

I plan on using a temperature controller for the fans on the lights .

modene said:

You mean run insulated ducting from outside into the lung room? .

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Yeah, or else it will sweat.

I don't think you will need a intake fan, just a damper. I would think in a small room, the fan would cycle way too much if thermostatically controlled.

- Jiji

jijiandfarmgang said:

Yeah, or else it will sweat.

I don't think you will need a intake fan, just a damper. I would think in a small room, the fan would cycle way too much if thermostatically controlled.

- Jiji

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Powered everything up last night .. It was about 70-78 outside and the room stayed at 82 w no ac.. So I think your right I won't need the intake fan in the lung room but going to look into the damper I'll probably need it once the temps drop.

I'm still thinking I may need a passive intake from the lung room.. Any suggestions? I was thinking of cutting a whole in the wall and using a furnace filter but I don't want to be cutting holes if I won't need them. Can anyone comment?

modene said:

I'm still thinking I may need a passive intake from the lung room.. Any suggestions? I was thinking of cutting a whole in the wall and using a furnace filter but I don't want to be cutting holes if I won't need them. Can anyone comment?

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.......how else would you get the air to exchange from lung room to grow room? confused again

- Jiji

edit- speaking of which, are you going to dehumidify in the lung room, cause that changes everything

jijiandfarmgang said:

.......how else would you get the air to exchange from lung room to grow room? confused again

- Jiji

edit- speaking of which, are you going to dehumidify in the lung room, cause that changes everything

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OK maybe that was a stupid question.. I guess I'd just be worried about too much cold air coming in when the lights are off but that's where that damper on the intake would come in .. Correct?

I wasn't planning on it we have really dry winters here I was gonna play that by ear. Why do you say that changes everything?

damper would be motorized and controlled by a thermostat. So it will only open to the set temperature.

If you put the dehumidifier in the lung room, there needs to be a recirculating active fan between both rooms. It wouldn't be effective to run your exhaust fans lights off and try to dehumidify with a dehumidifier if your in a humid area.

- Jiji