Controlling exhaust fan, two controllers?

.RootDown

.RootDown

Well-Known Member
I plan on using Co2 in my tent, but am concerned about heat and odor. I'd like to run the fan on a timer to run the exhaust overnight (maybe 15mins per hour) but I'd also like the fan to turn on if the temperature rises above a set limit.

I have a timer I can plug the fan into, and also an Inkbird temperature controller I can plug it into. Obviously I can't plug it into both, but can I wire an extension cord to accept inputs from both to turn on the fan when needed/timed? This would be super easy with DC.

thanks in advance!
 
.RootDown

.RootDown

Well-Known Member
Hugo Phurst said:
Think about it
Click to expand...
ok, I'll play-

If I plug the temp controller into the timer then an overheat will not exhaust when the timer is off- and if the timer is plugged into the temp controller I won't get timed exhaust unless the temp is too high. Care to elaborate?

I think it'd be really cool to run the exhaust fan through the carbon filter and cycle it back to the intake- and install a motorized dampener that activates when the temp gets too high to divert outside until the temperature normalizes. Totally possible, but the dampener alone is about four hundred bucks- and still need the controller to activate.
 
herballuvmonkey

herballuvmonkey

Well-Known Member
Think outside the box brotha. You can use a normal household thermostat an ac transformer for the low voltage and a 6 pin relay. The relay allows one high voltage at a time so if the t stat signals it’s too hot it will flip the relay and turn the the fan on other than. That it will run on a timer at 15 mins per hour. If you need a schematic dm me I will make one for you. Btw I am ex electrician an now a 6year ac tech. I have done this before and believe me it works good. Also for a damper find an ac guy he can get you a motorized damper for less than half that cost wholesale.
 
Boatguy

Boatguy

Well-Known Member
.RootDown said:
ok, I'll play-

If I plug the temp controller into the timer then an overheat will not exhaust when the timer is off- and if the timer is plugged into the temp controller I won't get timed exhaust unless the temp is too high. Care to elaborate?

I think it'd be really cool to run the exhaust fan through the carbon filter and cycle it back to the intake- and install a motorized dampener that activates when the temp gets too high to divert outside until the temperature normalizes. Totally possible, but the dampener alone is about four hundred bucks- and still need the controller to activate.
Click to expand...
If you are using a temp controller that will accept multiple programs just set the night temp very low so its always on, the timer takes care of the on and off.
vice versa for daytime, timer set for on, temp control does its job.
 
.RootDown

.RootDown

Well-Known Member
Hugo, that's exactly what I was thinking when I suggested rigging up an extension cord. I just was not sure if it was safe if both inputs came on at the same time.


Edit: yeah nevermind on that idea. The guy who made that was going for 240v, and multiple sources told him this is a fire hazzard. I think I'll exhaust by timer only, adjust times to deal with heat as needed.
 
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Socioman

Socioman

Member
Hello guys. I know that you have many experience in growing. I need to make a college project. and i choose your topic. I want to make a program for helping to control the growing. So I need your devices. I have a team AssignCode.com, which always provide me with excellence in every homework task
 
Hugo Phurst

Hugo Phurst

Well-Known Member
Socioman said:
Hello guys. I know that you have many experience in growing. I need to make a college project. and i choose your topic. I want to make a program for helping to control the growing. So I need your devices. I have a team AssignCode.com, which always provide me with excellence in every homework task
Click to expand...
ODG - it's been years since I've worked on designing anything like that.
So your looking for a programmable, multi-input, multi-output switching and control unit?
 
coreywebster

coreywebster

Well-Known Member
Co2 in a tent is a bit redundant since tents are not air tight.
If your worried about smell then you want fans running 24/7.

You cant keep the environment stable by letting it heat right up then whipping on an extractor and cooling it right down.
By doing what your planning your not getting a good environment, your not keeping smell under control, your not removing humidity and your not getting much out of the co2 to see a benefit. It would be more beneficial to just run standard 24/7 air exchange and forget about co2.
 
OldMedUser

OldMedUser

Well-Known Member
.RootDown said:
I plan on using Co2 in my tent, but am concerned about heat and odor. I'd like to run the fan on a timer to run the exhaust overnight (maybe 15mins per hour) but I'd also like the fan to turn on if the temperature rises above a set limit.

I have a timer I can plug the fan into, and also an Inkbird temperature controller I can plug it into. Obviously I can't plug it into both, but can I wire an extension cord to accept inputs from both to turn on the fan when needed/timed? This would be super easy with DC.

thanks in advance!
Click to expand...
Every time your fan goes on it'll suck out all your CO2 and you'll go thru lots. Better to have your fan on a heat/humidity controller with a speed controller jacked into the heat/rh unit. Or rig your room as a sealed grow room with a portable AC/dehumidifier unit to keep conditions right for your plants with enriched CO2 like I'm planning to do.

I've been using a good old analog one for years that uses a heat/cool thermostat wired to cool so when the hewat gets up it triggers the fan. A simple bathroom humidity thermo kicks in when the rh gets up. I've had to replace both parts a couple times in the last 17 years but it's a quick fix and I keep spares handy. Either unit can trigger the fan or both at the same time without sending 240V to the fan.

The speed controller on the left I made using a ceiling fan controller and NOT a light dimmer.

FanControl.jpg

The wiring is simple enough but you may get the heat/cool unit backwards and have it set to heat like your house thermostat but easy to test and switch the wires.

FanController.jpg
 
OldMedUser

OldMedUser

Well-Known Member
Hugo Phurst said:
Only if they're plugged into 2 different phases (like a split 2 phase kitchen plug)
Click to expand...
Think about it. You have two 120v hot wires leading to a single hot line feeding a 120V device so you'll be feeding 2x120V leads into one if both units go on at once. That gives you 240V at that end. I've done it and fried the switch on my variac rigging my furnace fan to run continuously. The variac still works but the switch is always on so have to unplug it to turn it off. Too lazy to replace the toggle switch. :)
 
Hugo Phurst

Hugo Phurst

Well-Known Member
OldMedUser said:
Think about it. You have two 120v hot wires leading to a single hot line feeding a 120V device so you'll be feeding 2x120V leads into one if both units go on at once. That gives you 240V at that end. I've done it and fried the switch on my variac rigging my furnace fan to run continuously. The variac still works but the switch is always on so have to unplug it to turn it off. Too lazy to replace the toggle switch. :)
Click to expand...
The two plugs in my living room wall socket are both 115VAC, and they do not add together to make 220VAC. They are the same point electricaly speaking, as I stated above.
The voltage doesn't split or add (unless you're talking phases), current does.
 
OldMedUser

OldMedUser

Well-Known Member
Do a little experiment. Wire up one of those double plugs and stick the male ends into any two sockets of your choice then plug a reading lamp into the female end and watch the bulb blow or use a multimeter to test the voltage at the hot plug at the female end. You feed two hots into one end and you double the voltage. Most likely you'll just flip the breaker as when you wire two hots together without resistance you create a short.

Just look at the breakers in your wall panel. Anything that uses 240V has two breakers to supply two 120V lines to the device to get 240V.

I've done a few wiring alterations in my own house and went and bought the book to make sure I do it right. No shorts or shocks yet. Used a 240V, 14/3 line to supply 2 duplex plugs in my grow room. One hot to each duplexand they share the neutral. Been working fine for 17 years. I plug my grow light. 1000W HPS atm, on one side with maybe a fan on the other plug and the other two plugs have their own 15 amp breaker for whatever I want to plug into them. The room heater is plugged into another circuit in common with my sump pump and the exhaust fan controllers.
 
GBAUTO

GBAUTO

Well-Known Member
What Hugo is referring to is how 240/120 is wired in your home. There are a pair of hot leads from the service transformer(those have 240v when measured from each other) and a neutral(this is at ground potential). When the voltage of either hot leg to neutral is measured, that's where you get 120v. It takes the combination of both 120v circuits to get 240v.
Another thought experiment- if both of those plugs are inserted into the same outlet where does 240v come from then?
 
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