Apologies in advance

[JoeBlow5823]

Huh? The heat goes through the fan either way!

Fan pulls air through filter, pushes air through air cooled hood and out of the tent....

 

[ttystikk]

Fan pulls air through filter, pushes air through air cooled hood and out of the tent....

View attachment 4677237

NO.

Filter -> hood -> duct -> fan, mounted outside the tent.

If you don't believe me, conduct this experiment;

Fire up your lamp inside the hood with the fan pushing air through it. Wait 20 minutes, feel the hood- be careful, the fucker will be hot!

Then, take the fan off and turn it around and remount it so it's pulling air through the same hood. Wait 20 minutes and feel the hood again. It will be cool.

You'll never push air through a hood again.

 

[JoeBlow5823]

NO.

Filter -> hood -> duct -> fan, mounted outside the tent.

If you don't believe me, conduct this experiment;

Fire up your lamp inside the hood with the fan pushing air through it. Wait 20 minutes, feel the hood- be careful, the fucker will be hot!

Then, take the fan off and turn it around and remount it so it's pulling air through the same hood. Wait 20 minutes and feel the hood again. It will be cool.

You'll never push air through a hood again.

Ive been pushing air through my hood for multiple grows. It has never gotten hot. Ive measured every part of it with my laser thermometer- directly over the bulb it gets to a blistering 90 degrees. The rest of the hood stays under 85. I just ran it for 4 months like this.

 

[Renfro]

I dunno, I am confused on this one, to me it just seems like CFM is CFM, either way it's lined up. Now if something was happening to mess up air flow more in one arrangement then I could see there being a performance difference. Still it seems like the reflector is gonna add it's specific turbulence either way, @ttystikk are you saying that the push setup is more turbulent because the air is coming out of the blower already turbulent and then hits the awkward box before going into the duct? I am not disputing that you noticed a difference in your real world testing, I am just trying to figure out why, whats the physics behind it. It seems like CFM would be CFM either way.

 

[.Smoke]

I dunno, I am confused on this one, to me it just seems like CFM is CFM, either way it's lined up. Now if something was happening to mess up air flow more in one arrangement then I could see there being a performance difference. Still it seems like the reflector is gonna add it's specific turbulence either way, @ttystikk are you saying that the push setup is more turbulent because the air is coming out of the blower already turbulent and then hits the awkward box before going into the duct? I am not disputing that you noticed a difference in your real world testing, I am just trying to figure out why, whats the physics behind it. It seems like CFM would be CFM either way.

Pushing air through adds heat from the fan motor to the air. The air particles getting churned, compressed and forced through the fan also raises the temperature of the "cool air" being blown into the reflector hood. In essence, reducing the cooling capability of the air resulting in (a minor) increase in hood temperature and overall tent temperatures.

Placing the fan outside negates these factors.
Pulling the air is easier on the motor due to the lack of back pressure, most likely resulting in a more efficient, higher CFM flow.

I've personally had lower tent temperatures just from pulling my air instead of pushing it like @ttystikk said.

 

[Renfro]

Pushing air through adds heat from the fan motor to the air. The air particles getting churned, compressed and forced through the air also raises the temperature of the "cool air" being blown into the reflector hood.

Hmm I'd like to see an IR gun reading on the blower output to prove that, I find it hard to believe that with the low wattage of the blower motor and the amount of air going through it that it wouldn't raise the air temperature more than a cunt hair. We aren't compressing the air enough to make it significantly hotter either. I just can't see it...

 

[.Smoke]

Hmm I'd like to see an IR gun reading on the blower output to prove that, I find it hard to believe that with the low wattage of the blower motor and the amount of air going through it that it wouldn't raise the air temperature more than a cunt hair. We aren't compressing the air enough to make it significantly hotter either. I just can't see it...

I agree any change would be minimal.
There's got to be something to it, or maybe @ttystikk and I both just smoked a little too much before testing.
Done that before.

 

[Renfro]

There's got to be something to it, or maybe @ttystikk and I both just smoked a little too much before testing.
Done that before.

lol haven't we all.

 

[2com]

co2 supplementing?

Forget about it until you get some experience, is what I'd say in regards to this question.

TLDR:
Fan: DC inline fan (power saving, very compact and light, very dimmable and designed for such use). "Oversize" it and dim for quieter an easier operation.
Lights: A reputable led brand, or I guess a well reputable knock off of one (I see you've ordered already, all good). DIY is a good way to save money; future reference.
Seems you have everything else sorted. Enjoy, dude.

In regards to inline fan selection, a "DC inline fan" is what I'd recommend. They're dimmable, and they're meant to be dimmable, and often - if not always - come with a dimmer. They don't just "pulse the electricity", which is what "speedster" type dimmers connected to a standard (vortex style) inline fan does, as best as I remember, which technically "isn't good" for the motor, and creates that hum/noise. DC fans also dim lower, and again, they're designed to do this. "Hyperfan" is just a brand example, check amazon for "DC inline fan" probably, for more. I'm almost 100% sure the AC infinity fans are DC fans, and they come in a temp regulated or humidity regulated version, I think. Another benefit is that they (DC) use much less power than a "standard" inline fan.

Edit: Removed shit that doesn't aid in OP's question.

Good luck on your first grow, guy.

 

[JoeBlow5823]

I agree any change would be minimal.
There's got to be something to it, or maybe @ttystikk and I both just smoked a little too much before testing.
Done that before.

My point exactly, the difference is minuscule. If your hood is getting to hot, there is a much bigger issue at hand.

 

[ttystikk]

Hmm I'd like to see an IR gun reading on the blower output to prove that, I find it hard to believe that with the low wattage of the blower motor and the amount of air going through it that it wouldn't raise the air temperature more than a cunt hair. We aren't compressing the air enough to make it significantly hotter either. I just can't see it...

I want measuring the remotest of the output air, I was measuring the temperature of the hood itself.

Anytime you blew air you compress it and one of the basic principles of compressing a gas is that in doing so, you heat it.

When blowing air through the hood, the hood got and stayed hot.

When drawing air through the hood- same hood, same lamp, same fan- the hood stayed cool.

It was not a subtle difference.

 

[ttystikk]

Pushing air through adds heat from the fan motor to the air. The air particles getting churned, compressed and forced through the fan also raises the temperature of the "cool air" being blown into the reflector hood. In essence, reducing the cooling capability of the air resulting in (a minor) increase in hood temperature and overall tent temperatures.

Placing the fan outside negates these factors.
Pulling the air is easier on the motor due to the lack of back pressure, most likely resulting in a more efficient, higher CFM flow.

I've personally had lower tent temperatures just from pulling my air instead of pushing it like @ttystikk said.

Your results mirror mine, even if I'm not sure I agree with your explanation for why it works that way.

 

[ttystikk]

I agree any change would be minimal.
There's got to be something to it, or maybe @ttystikk and I both just smoked a little too much before testing.
Done that before.

Not minimal. When I did my back to back test, the difference was between a hood cool to the touch and one that was too hot to hold my hand on.

 

[Renfro]

I still don't see there being enough pressure to actually heat the air very much. If that was the case you could turn on the air handler blower on a central air system and it would heat the house lol.

 

[JoeBlow5823]

Not minimal. When I did my back to back test, the difference was between a hood cool to the touch and one that was too hot to hold my hand on.

Yeah I'm not buying it, something about your setup must have been different other than where the fan was positioned. Ive been blowing air through my hood for a long time and it stays cool to the touch.

I still don't see there being enough pressure to actually heat the air very much. If that was the case you could turn on the air handler blower on a central air system and it would heat the house lol.

Yeah something about his "test" is off.

 

[Renfro]

Yeah I'm not buying it, something about your setup must have been different other than where the fan was positioned. Ive been blowing air through my hood for a long time and it stays cool to the touch.


Yeah something about his "test" is off.

i have to agree.

 

[ttystikk]

i have to agree.

It was an 8" fan on an 8"magnum XXXL hood with one SE 1000W HPS lamp in it. The only change was turning the fan around from blowing to sucking.

Try it yourself instead of doubting me with no evidence.

 

[Renfro]

Well I would test it just out of curiosity, if I had the gear to do it. I think I have an old air cooled 6" reflector in the garage but no spare blowers laying around. Maybe I can pick one up cheap on craigslist lol. I really am curious. I believe you when you say what you experienced, I am not calling you a liar, I am just trying to come to terms with why it happened.

A reasonably powerful ducted fan situation might be producing a pressure as high as 0.5" WC and thats about 0.018 PSI. Thats all the fan could actually compress the air in the duct system. I just don't see that small amount of compression heating the air by a measurable amount.

As to the motor dissipating heat, it's cooling itself constantly and yes that would warm the air stream but only a tiny amount due to the volume of air being moved.

I can only surmise that the airflow was somehow impeded with the push arrangement, but I really would love to test this. I will see what I can come up with.

 

[NukaKola]

Pulling is slightly more efficient than pushing but I don't believe it is because of the heat from the fan. I think it has to do with the fact that when pushing the air can swirl in the hood causing turbulence and disrupting the flow of air, whereas pulling the air is going to travel the path of least resistance in a more unidirectional fashion.

At least that is my assumption. Would be interesting to test with an infrared camera.

 

[Renfro]

I think it has to do with the fact that when pushing the air can swirl in the hood causing turbulence and disrupting the flow of air, whereas pulling the air is going to travel the path of least resistance in a more unidirectional fashion.

At least that is my assumption. Would be interesting to test with an infrared camera.

Thats what I am thinking too, it's the only thing that makes sense. I mean if the air is moving like it should then the whole system would be cooled. So the air isn't moving like it should.