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Vertical (no hood), tent or enclosure, ventilation/cooling calculation? Thread Tools Search this Thread
Old 05-22-2017, 05:34 PM #1
zeke99
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Vertical (no hood), tent or enclosure, ventilation/cooling calculation?

Do we know now how many times per minute that air has to be exchanged in order to keep the temperature inside of a tent the same as the temperature outside of the tent with stacked HID bulbs, 2 x 600w, 3 x 600w, 1 x 1k, 2 x 1K, etc. when the tent is NOT being ventilated into the room that it sits in?

Is it 1x, 2x, 3x (per minute air exchange)?

And if we do, do we know more than that, for example, maintaining a +5 and +10 degree difference (inside the tent)?

No cool tubes, no hoods, just bare bulbs.

Please share your data. Tent size, wattage, CFM, temp differential.


....

Specifically I am erecting a 162.5 cubic foot tent with a 1K bulb. I have the ability to ventilate from the tent, directly out a window, so the temperatures in the room containing the tent will only be impacted by the presence of the ballast.

Last edited by zeke99; 05-23-2017 at 04:44 PM..
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Old 05-23-2017, 10:57 PM #2
zeke99
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Maybe this is what I was looking for? (Found in several threads).

Quote:
Just a quick note, you can calculate the need for cfm with this:
V = (3 x P) / ΔT

So if: P = 600W, ΔT = 5C (means you want the temps be 5C over ambient) -> (3 x 600) / 5 = 360 m3/h
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Old 05-25-2017, 06:14 PM #3
zeke99
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I cannot wrap my head around the previous calculation, that uses Delta T. After reading about it on a couple of different pro HVAC websites, I simply do not see how it applies to ventilating a grow tent. Which isn't to say that ultimately doesn't; again it is something that might be too confusing for me to understand at this point in time.

*********

Intuitively, the following makes more sense.

via: https://continentalfan.com/general-v...-to-ventilate/

Quote:
Heat removal method

When the temperature of a space is higher than the ambient outdoor temperature, general ventilation can be used to provide “free” cooling. What is needed to calculate airflow is the amount of heat to be removed in BTU/hr, the desired indoor temperature and design outdoor dry bulb temperature.

Example: 200,000 BTU/hr to be removed, 70 degree desired indoor temperature and 50 outdoor dry bulb temperature.

Airflow = Q = 200,000 (BTU/hr) / (1.08×20) = 9,260 cfm
via: https://www.sunlightsupply.com/page/...ked-questions/

Quote:
How many BTU’s Does my system and reflectors create?
1 watt = 3.41 btu per hour.

1000watt = 3,412 btu per hour

Last edited by zeke99; 05-25-2017 at 06:32 PM..
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