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admin should sticky this thread, please and thank you.
thanks rg!
thanks rg!
transverse
New member
-moderator please delete-
echo_chamber
Active member
A great read, thanks redgreenery. Very thorough and this thread made me realize how vital airflow is, and how at least 80% of the growers out there are doing it all wrong. I went out and bought an Anemometer, Manometer and Psychromter to test my room and the Anemometer really showed me some numbers that were frightening. I re did some duct work and a 60% increase in performance so far.
I have a question regarding Manometer use in the garden though. At what point in your duct work do you want to place the static pressure probes attached to the Manometer?
I've got mine set to "Inches H20" and i'm not sure if one probe should go right where the air comes into the room and the other probe inside the exhaust of the fan?
I want to test the static pressure of my air conditioner box as well, which has a 400 CFM fan pulling its hot air out of the room. I'm wondering how i'd "probe" the a/c as well, at what points..
I did some googling and some youtubing and not much data out there as applied to our glorious hobby, mainly multi ton HVAC demos.
Any help from anyone on Manometer use in the garden would be awesome, thanks!
I have a question regarding Manometer use in the garden though. At what point in your duct work do you want to place the static pressure probes attached to the Manometer?
I've got mine set to "Inches H20" and i'm not sure if one probe should go right where the air comes into the room and the other probe inside the exhaust of the fan?
I want to test the static pressure of my air conditioner box as well, which has a 400 CFM fan pulling its hot air out of the room. I'm wondering how i'd "probe" the a/c as well, at what points..
I did some googling and some youtubing and not much data out there as applied to our glorious hobby, mainly multi ton HVAC demos.
Any help from anyone on Manometer use in the garden would be awesome, thanks!
farmanimal
New member
I'm starting to build my grow cab just can't figure out what size to make the intake holes. My cab is 78"H x 36"W x 26"D. I'm using a 150cfm exhaust with scrubber. A cooltube with two inline fans
farmanimal
New member
My exhaust hole is 6in. So would 6.5in be good for intake. I think that would be to big of a hole
farmanimal
New member
What size holes would you recommend? And how many
echo_chamber
Active member
Farmanimal, since you are unsure, you neeed to go 2x the size of your outtake, so 12", or two 6" circular holes. Not enough air intake will be the success or failure of your garden most likely. Air is serious business, plants need it. They suffer without the right amount.
farmanimal
New member
Thnx alot. But I think six inch holes are to big. Can I do 4 3inch holes
6 inch hole: A = 113.09733552923 in2
3 inch hole: A = 28.274333882308 in2 (I think 6 3 inch holes would be great.)
you can use this area calculator if you need:
http://www.calculatorsoup.com/calculators/geometry-plane/circle.php
3 inch hole: A = 28.274333882308 in2 (I think 6 3 inch holes would be great.)
you can use this area calculator if you need:
http://www.calculatorsoup.com/calculators/geometry-plane/circle.php
lung room and vent size
lung room and vent size
ok I have a 12 inch 1250cfm blower pulling heat out of the top of one end of the room and a 10 inch 750 cfm blower on the other end doing the same and dumping into the top of the lung room ,how big should the holes be dumping from the lung room to grow room?im thinking having them 2-3 feet of the floor so there is alway cooled air in that room to mix with the hot air there is a 28,000 btu a/c in the lung room 2 dehum, 5 ballast help
lung room and vent size
ok I have a 12 inch 1250cfm blower pulling heat out of the top of one end of the room and a 10 inch 750 cfm blower on the other end doing the same and dumping into the top of the lung room ,how big should the holes be dumping from the lung room to grow room?im thinking having them 2-3 feet of the floor so there is alway cooled air in that room to mix with the hot air there is a 28,000 btu a/c in the lung room 2 dehum, 5 ballast help
farmanimal
New member
thnx exploziv_gbb
G
guest 77721
Thanks for the props! I'm sure you will be able to tune your system in now that you have the right tools.
With a manometer, there should be two tubes combined into one probe. The straight probe at 90* to airflow measures static pressure. The 90* bent probe is turned into the airflow to measure total pressure. The velocity pressure is the total pressure - static pressure. The airflow is calculated from the velocity pressure.
You can also take static pressure readings with a single straight probe. If the total pressure is known or measured at the fan exhaust or intake, the velocity pressure can be calculated by subtracting the static pressure.
When taking pressure readings, it is best to take several measurements across the cross section of a duct then average them to get a truer reading.
If you work from intake to exhaust, the higher static pressures will indicate blockages further downstream. It's like water flowing in a creek. If you put a dam across the creek, the water level will rise upstream until it flows over the dam.
If you can, can you post a diagram with your system and the pressure readings at various locations?
echo_chamber
Active member
Without the filter attached, and using a Can Fan 6" rated @ 270CFM, i get a reading of 0.15" wC with the probes setup at the intake and exhaust of the entire duct run of about 8 feet.. Looking at the spec sheet of the fan, that means i'm getting around 240 of the 270 CFM. I'm using flex duct and 90° elbows at each joint. I did not test with my filter yet as i've not hung it up yet.
Dieselstyle
New member
Question for all you math savy individuals. So if I have a room that is 1,560cu.ft. I want to achieve five minutes per air change. Which comes out: room volume/(min/change) = 1560/(5min/chg) = 312 cuft/ min. Now do I need to look for a filter and fan combo that achieves this CFM? Also, if I were to use an intake fan to draw air into the room, the fan would need to be equal or less than the 312 cuft/min would this be correct? In terms of filter and fan combo, I imagine that the bigger than fan and filter that meets the cfm, the more quiet in operation right? Would it be more efficient to change the air every three minutes in the flower due to a more extensive odor or it does not really matter because the room is completely sealed?
