New cab reaching 90+ degrees w/ low humidity

J

journalreader

Well-Known Member
Renfro said:
If you have access to a handheld anemometer, you can measure the velocity of the air exiting the exhaust duct. Convert whatever number you get into feet per minute.

Do a little math and we get an area of 12.5 square inches on the 4 inch duct, lets just call it 12 square inches since it's accordion duct. Thats one square foot.

So if we take the linear speed of the air exiting the 4 inch duct and its 60 feet per minute, x 1 square foot, we get 60 CFM.

In this manner we can determine exactly how well the system in performing.
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Id have to go buy one, which im not necessarily opposed to doing.. any other way to measure this in the meantime?

coreywebster said:
Lights like that are made with minimal heat sink so they have to run active cooling which means they blow hot air out which is very easy to notice.

I don't suppose you can return the light?
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I have 15 days from purchase to return, so a few days left. Now im just paranoid about leaving these seedlings at my window while I shop for a new light lol. Starting to poke around the LED forum for better options.
 
1

1212ham

Well-Known Member
journalreader said:
I have 15 days from purchase to return, so a few days left. Now im just paranoid about leaving these seedlings at my window while I shop for a new light lol. Starting to poke around the LED forum for better options.
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Go for it, you won't regret it! Those seedlings don't need much light at this stage, a compact florescent is common. Lay a little sheat of aluminum foil over the thermometer, it only needs to block the direct light from above. :wink:
 
Renfro

Renfro

Well-Known Member
Dr.J20

Dr.J20

Well-Known Member
Renfro said:
Reducing is definitely going to kill flow.
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how do you like to connect 6" to 4" port? I was just thinking about quick fixes anyhow, the right moves seem to be switching up the light at this point.

@journalreader cfls are fine for vegging while you wait for your light, or if you get antsy and feel like you need to do something more, a 2 lamp T5 with some HO T5 aquarium lights (zoomed flora suns are perfect) work nicely.

good luck and when you get fed up with meters and water come play in the dirt over in organics!

:leaf: :peace: :leaf:
 
J

journalreader

Well-Known Member
Renfro said:
If you have access to a handheld anemometer, you can measure the velocity of the air exiting the exhaust duct. Convert whatever number you get into feet per minute.

Do a little math and we get an area of 12.5 square inches on the 4 inch duct, lets just call it 12 square inches since it's accordion duct. Thats one square foot.

So if we take the linear speed of the air exiting the 4 inch duct and its 60 feet per minute, x 1 square foot, we get 60 CFM.

In this manner we can determine exactly how well the system in performing.
Click to expand...
Measuring my airspeed on medium is around 4.5 m/s. High is 5.3 m/s. I feel like that could be better but it's still enough to circulate air efficiently, correct?
 
Renfro

Renfro

Well-Known Member
journalreader said:
Measuring my airspeed on medium is around 4.5 m/s. High is 5.3 m/s. I feel like that could be better but it's still enough to circulate air efficiently, correct?
Click to expand...
So if you are getting 4.5 m/s that would equate to 14.7638 ft/s and therefore 885 ft/min and since we mathed out the 4 inch at 12 square inches (0.08333 sqft) you are achieving a real world CFM of 73.8 on medium and on high 87 CFM.

You have about 23 cubic feet in your cab if my math is correct. That means you are able to exchange the air volume about 3.85 times a minute when on high. That should be enough provided the ambient (intake) air temperature is cool enough, so we are at the point where we are looking at intake temperature as the problem.
 
dbz

dbz

Well-Known Member
Did I miss something or do you only have a 4 inch passive intake?
Maybe I missed something but if it's passive you need more than that on the passive intake in order for your exhaust fan to be efficient.
 
Renfro

Renfro

Well-Known Member
dbz said:
Did I miss something or do you only have a 4 inch passive intake?
Maybe I missed something but if it's passive you need more than that on the passive intake in order for your exhaust fan to be efficient.
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I think he has two passive 4 inch intakes.

journalreader said:
Measuring my airspeed on medium is around 4.5 m/s. High is 5.3 m/s. I feel like that could be better but it's still enough to circulate air efficiently, correct?
Click to expand...
When you measured this you did have the cab closed so all the air must come in through the intakes correct?
 
J

journalreader

Well-Known Member
dbz said:
Did I miss something or do you only have a 4 inch passive intake?
Maybe I missed something but if it's passive you need more than that on the passive intake in order for your exhaust fan to be efficient.
Click to expand...
I have 2 4" passive holes and 2 small 3/4" holes as well.

Renfro said:
When you measured this you did have the cab closed so all the air must come in through the intakes correct?
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That is correct. I'm exploring some portable A/C options that I can run in the room to help. Until it cools down around here I'll be having to deal with high temps unless I move the cab to another area, which isn't doable.
 
Renfro

Renfro

Well-Known Member
journalreader said:
That is correct. I'm exploring some portable A/C options that I can run in the room to help. Until it cools down around here I'll be having to deal with high temps unless I move the cab to another area, which isn't doable.
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Well the measurements you provided allowed us to determine that your exhaust system is doing it's job so the portable AC unit is what you need, something to get the intake temperatures down. Summers are tough, it's hotter than hades here, had an AC unit shit on me in the living area, getting into the upper 80's and even 90's in here during the late afternoon. Ordered an new portable, tore open the dead one and the condenser fan is toast so I am going to root up an old inline fan from the garage and try to get some air flow over the coil lol.
 
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