Slowing Down a Vent Fan

wow that is small.could use a timer and set it for 15 minutes every hour

actually, i intend for a timer to shut it off for a short spell thrice a day just to keep it safe from overheating.

but this grow space is in my garage and the temps in south U.S. hit triple digits in summer.

what about just adding a small window A/C unit to the grow area to keep it cool? I guess maybe there wouldn't be room for that huh. Yeah now that I look back at the dimensions of your grow room, it is a bit small, I agree that a 50 CFM fan would work just fine. I'm gone, TTYL

I feel ya I just had to buy a portable ac unit and Im in the north.Could run and ac line from your attic ducts to the garage cieling

Here's something else...it isn't "cheap"...but I swear it's worth EVERY cent
and would work incredibly well in anything from a cab to a full-sized room.

Quantem Moisture Proof Wall Mount Variable Speed Controller - QC Supply

top dial is the rheastat. The dial is in % of full speed. The fan runs at this user-set speed until...

the set/chosen TEMP limit on the second dial is exceeded then the fan runs FULL speed until the room cools down past the set temp. At that point the fan again runs at the rheastat setting/ratio/%of full speed until the room again heats up above the set point.

Great for auto adjustment of lights on/full speed..lights off/partial speed. You can look all over and there isn't a big $$$ controller out there that has this feature on it. they all just turn the fan (outlet) on or off....

There's also a digital model.

fwiw. I hope the link helps someone else out there. This has been a great thing for my room.

FilthyFletch said:

Could run and ac line from your attic ducts to the garage cieling

Click to expand...

that's exactly what i've done. but i have to use a vent to pull it thru the room and out over my lamp to air cool it.

but it's recommended to have 5 air changes a minute. that's equal to a 30 CFM fan. i could use this fan at about half speed.

Hmmm.. Years back I had to take a year course in electronics and Home wiring. In one of these course, they taught us how to cut down the electical use in a house. One of the ways was to install dimmer switches on the fans. These dimmer switches do work. BUT!!!! You can not slow down the fan passed 60-70% or you will end up getting a Buzzing noise. If you have a 50CFM fan,, which that is very small to start with, and this 50 CFM fan is to much, and 65% of the 50 CFM is still to much volume. Then I would suggest going and buying a smaller fan. Either that or just place a restrictor over the inlet or outlet of the fan.

You need to move 30 CFM? that is just over 3'X3'X3'. And that suggestion is a MIN, not an EXACT number. More is good,, less is not. Use the 50 CFM full blast.

I agree with what chabnock says can't have to much the more circulation you have the more co2 gets to the plants. helps keep down on the mold and some pests too Let RIP it wont hurt your plants

If you have a set speed you would like to run the fan at, you can always just place a simple resistor in there for like 2 dollars.

On the fan look for a voltage and amperage value.

Using this, calculate the resistance of the fan by R=V/I.
So if you had a 12V fan running at 0.2A, you would do 12/0.2, giving you your resistance value.

Then, say you want to run the fan at 1/2 speed, you would want a new voltage drop on the fan of 6V.

So now you must find out your new current. This would be:
6V=(Calculated Resistance)*(New Amperage)

Now, you know you want a voltage drop of 6 on the resistor(Half speed), so now you can calculate your resistor value.
6V=(New Amperage)*(Resistance Value Needed)

Then just put that bad girl in series with your fan and you have a 1/2 speed fan.

cool.i always wondered how to use resistors but had never research it. i'll check it out. thank you.