HOW TO make a fan that comes on once room hits a certain temp

Tremayne

Member
i found this while surfing the web for ways to cool down my growbox and thought someone might find this useful and was also wondering if anyone is currently using a system similar to this in their grow box?

Things You'll Need


  • Temperature sensitive switch
  • 3-1/2-inch computer fan
  • AC-to-DC Plug
  • Drill
  • 3-1/2-inch hole saw
  • Wire strippers
  • Electrical tape
  • Butt connectors
  • Wire fasteners
 

smoke and coke

Well-Known Member
i use a stanley blower for an exhaust. for the controls i use a temp control that closes on temp rise. the output is wired in parallel to the output of a timer. so either the temp gets at a preset setting or the timer setting will turn the fan on and off.
 

Tremayne

Member
my actual grow fan currently stays on a static 24 hour setting, but i'm thinking of making an air cooled grow hood and adding this would turn on the fan once the hood reaches a certain temp.
 

smoke and coke

Well-Known Member
my actual grow fan currently stays on a static 24 hour setting, but i'm thinking of making an air cooled grow hood and adding this would turn on the fan once the hood reaches a certain temp.
for an air cooled hood, i would have the fan on if the light is on. to do a room control i would use a seperate fan.
 

TheTimeKeeper

Well-Known Member
Hey Tremayne,

I've built one, Variac as the speed controller, ATC-800 as the high temp controller.. mine is designed to only kick in fan at 100% once the set temp is reached, otherwise it sits on the variac set speed... nice unit and not too hard to make, though variac's aren't cheap. In saying how nice the unit is, the reality is that my fan is well powerful enough to vent well even at a low variac setting, I think I've only heard the high temp (100% fan) kick in once and even when it did it didn't really help the temps as it was such a hot summers day. At the end of the day a cheaper and easier to make variac speed controller would have done the job fine.. though if you want to pursue and need a hand lemme know. TTK
 

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smoke and coke

Well-Known Member
hey TTK

i could have built the control for free when i worked at a mill. i had control of ordering parts for our shop plus all the stuff we had laying around. what i have now works pretty good. my next upgrade will be an inline fan although that stanley blower does a great job.







 

TheTimeKeeper

Well-Known Member
Hey S&C,

The stanley blower looks mad!! But hey, if it works then why change it!? Shame about not still working where you did, wish I had my hands on allsorts of bits and bobs, I'd be making some mad controllers!

I use a mixed flow in-line fan, when recently getting back into growing I researched every component to the last detail, and from my research the mixed flow appeared to be the best choice for suction through carbon filter (and pushing out) as well as being relatively quiet. I ordered direct from a distributor and had it couriered to me... saved about 50% rrp by doing so (even though I couldn't purchase it locally at any shop). I'll get another one soon so I'm replacing it every 2/3 years (like a hard drive on a computer!), then I'll use the old one for household ventilation! I strongly recommend mixed flow fans though I've not had any exp with centrifugal's so can't comment on their noise - I have hung up my fan like yours on bunjie's, and have enclosed the fan in a box surrounded by insulation of sorts, can't hear the fan, just the sound of moving air, but it's quiet enough to sleep next to!... TTK
 

smoke and coke

Well-Known Member
i dont have to worry about the noise or the smell so no filter.but i figured if it cuts down on some vibration then why not hang it. i moved it to another side of the room and have it as high to the ceiling as i can. i just dont have room for it anywhere without being in the way or hitting my head on it. been thinking of putting the fan outside the room but yeah why change it if it works. the stanley blower was 25 bucks on ebay new and has been in use for maybe 7 flower cycles so i think i need to get a new one soon for a back up.

i have one of those bounce house blowers. it only has like a 3" exhaust but it blows alot of air. never had it hooked up to see how it works. its also really loud.

do you have any pics of your ventilation?
 

TheTimeKeeper

Well-Known Member
Hey S&C,

See pics for my setup... I thought this through alot!

Why it's designed this way;
- Easy to change carbon filter - carbon filter sits upside down in airtight box to which the air cooled hood connects to, fan is underneath filter hooked up directly
- Pumps hot air out at top corner of cabinet - so the hot air is not going straight back in the intake (at the bottom of the cabinet literally as can is on wheels) - this is why the acoustic ducting is connected directly to the fan and goes back up, through the area containing the filter (connected via duct-to-wall connectors) and out in the top corner, externally there is a small prop to ensure the outgoing hot air goes 'up' not back down the wall behind and recirculate.
- The mother plant area under all this has a passive intake to which it's outtake is the utility area of the cabinet, from the utility area there are 3 large holes which sit under my drain (to waste) table in the flower area to ensure no light leaks - there are also three large holes as passive intakes in the utility area, however I cover these up to control the airflow through the mother plant area (i.e. if I cover all the utility intakes, all intake air MUST come through the mother plant area, if I uncover all the utility area intakes not much air comes through the mother plant area and they cook)

That make sense!? It looks much better now it's painted though!! TTK :D
 

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