Ventilation Question

[ross]

Ok I'm going to have some explaining to do so bare with me if you will. I have a tent inside a bedroom and the way I had previously been venting is exhausting the tent/carbon filter and lights into the room then exhausting the bedroom with a window fan connected to a Titan day/night temp controller.

But, in preparation for the summer, I started exhausting my tent DIRECTLY outside and put my window exhaust fan in the incoming window connected to the Titan temp controller incase a boost was needed. But, with all the fans on high it can get too cold on cold nights. This used to not matter cause the room the tent was in would heat up when the fans were on high then the window fan would exhaust it. But now all this heat is going directly outside.

I bought a Titan temp fan SPEED controller so i dont have to have the fans on high all the time, and I didnt want to get the ON/OFF temp controller I was using for the window exhaust fan because I didnt want my carbon filter and light hood fans ever OFF.

I used to open and close the windows every night and morning because with open windows during the day it would get too cold for the "plant night". But, when I routed all my ventilation directly outside I put a 6in flapper output port in the exhaust window and flappers on the incoming air window in hopes of not having to open/close the windows everyday because obviously being home at those times everyday is hard.

But now my new problem is if I keep the carbon filter on 24/7 like I had, I am now pulling in cold air during the day since the tent is now vented outside. And side problem, I cant have that fan connected to my new temp fan speed controller because it is on the timer for the lights. I know this is a complex problem and a solution might be hard but now that you guys know what I'm working with maybe you could throw out some ideas and share what techniques/set ups whatever you use for venting. Thanks for reading sorry it was so long tried to be concise.

 

[ShecallshimThor]

The only thing I can think of trying (I have no experience w tents though)
Is to passively intake air from the room, the way I read the above is you are bringing cold air into the tent and exhausting out the window.

No air from the bedroom actually goes through the tent?
If it were me I would take exhaust fan off the timer that is attached to the light and run the exhaust 24/7 on its own plug or speed controller. I would remove the fan you are using to push air in, pull the room temp air from the bedroom through the tent. If that was to warm I would crack a window to bring the bedroom temp down or heat the bedroom if the problem was being cold.

Just reread your thread and I think if you could get the bedroom at a stable temp you shouldn't have to be open and closing the window every day. But might have to make weekly adjustment to the window depending on weather
Now this has little experience behind it, only my ingenuity and what I would try in your scenario.

If this is bad advice someone speak up an correct me lol

 

[pcduck]

What kind of low temps are we talking?

Just run your carbon filter fans during lights on or put on timer to exhaust once every couple of hours for a few minutes for humidity control

 

[ross]

If I only run the carbon filter during lights on my place starts to smell too bad. Last night was 63 a little above canopy when usually its 75. Nothing horrible. The tent gets the bedroom air passively from the negative pressure with the carbon filter exhausting outside 24/7. I dont mess with the windows anymore cause they have plywood in the openings with one 6" output vent in the exhaust window and 4 4" flapper vents in the incoming air window. Last night i put a towel up against the input flapper vents to hold them more closed (kind of a lame effort). Right now the bedroom door is open so there isnt negative pressure pulling the flappers open in the window thus not bringing in cold air but instead bringing it from the house (not the most energy efficient given its exhausting it outside). And I forgot to add that this bedroom is seperate from the heating of the rest of the house. It is the only room without central air.

 

[Hushpuppy]

I would put it back the way you had it, where the tent is exausting into the room and then use a timer on the window fan to exaust the air from the room periodically. Then just let the outer intake air to be pulled in passively as needed. This will allow time for the heated air to mix with the cool outside air and maintain a proper temp. Then get another oscillating fan and put in the room to constantly mix the air.

You said it gets cold during the "dark period" because of it running constantly. You can set the timer to turn off and on periodically during this period so that there is fresh air coming in some but not enough to make the space cold. During their "dark period", the plants don't need as much "fresh" air anyway as they do during the "light period" so you could (for example) leave the fan running constantly during the "light period" then say only 15 minutes every 2 hours during the "dark period". Or if it is still getting too cold during the "light period", you turn the outer exaust fan off for 15minutes every 2hrs.

I don't know the titan controllers so you may be able to control the fans the way I described through the titan. But you will have to work with it some and experiment until you get the right temps. Hope this helps

 

[ross]

Thanks for the help. The problem with the way I had it was on warm nights my old box fan exhaust set up didnt pull enough air to cool the room. I think I might just exhaust the light heat out and keep the carbon filter exhausting into the room so during lights off its not still pulling air from outside

 

[Hushpuppy]

So you have your lights and your carbon filter on separate exaust fans? Where is the light vent pulling its air from to feed to the lights?

The way I have mine is my carbon filter is connected to the lights and then the lights are connected to the exaust fan that is mounted next to the exit so that it pulls all of the air in the tent through the filter than the lights before going outside. If yours was set up like that then you could get a "Y" connector and connect a second fan to exaust to the inside and keep the one exausting to the outside. Then using an interlock switch tied to a timer/temp sensor, you could har the outside exausting fan run while the lights are on and then when the temps inside get too cool, the outer fan shuts off and the inner exaust fan turns on to recirculate the air.

 

[ross]

Yea separate fans for lights/carbon filter. Lights just pull air from the bedroom. Maybe I could do something like hook up the lights to the carbon filter but usually I like the fans on high cooling the lights and I'm afraid it might make the tent too cold.

 

[Hushpuppy]

Hey I drew this representation of the tent with the carbon filter connected to the light hood with flex hose. Is your tent big enough to hang the carbon filter up inside the tent, in the top and attach it to the lights then run the exaust from the lights to a wye connector like I have shown. Then one side of the wye connects to the window exaust, while the other side is open to the room. You could connect the first exaust fan to the output side of the wye that is going to the window, then connect the other fan to the other output side of the wye that comes back into the room. Then you run the power for both fans to a timed or temp sense flip/flop switch. This will turn on one or the other of the fans so that the ventilation to the tent is on all of the time and is scrubbing the air constantly. And according to how you set it, the exaust fan to the outside would run whenever the lights are on unless the room temp gets too low, and then it will turn off the exaust fan and turn on the recirculate fan that will bring the light heated air back into the room.

If you don't have a controller to work the 2 fans then you can use sincronized timers and have them set on cycle periods so that when one turns off the other turns on. I hope this makes sense to you, and/or helps you come up with something

 

[ross]

Thanks for the help I switched it around a bit similar to your suggestion. So now I'm pulling through the carbon filter and hoods with the same fans that put it back into the room. And the room is being exhausted separately with another inline fan.

 

[Hushpuppy]

Yeah thats it. Then you can leave the light fans running constantly to keep it filtered and adjust the window fan to control the temps in the room. Then this summer you can connect a portable ac unit in there to cool things down a bit. That is what I have to do with mine during the summer. I got a nice portable ac unit from home depot for under $300, and it also works as a dehumidifier as well.