Topic helping new growers on air flow and heat reduction

I've seen a lot of posts and in my life many new and some experienced growers using cool tubes and vented hoods with inline fans running independent air flow through a system which isn't enclosed. The only reason you should use a cool tube is using the light vertically in an totally enclosed application with Co2. The Cool tubes with the little wings are very inefficient.

If you have a tent with vents and aren't using Co2 there's no reason to waste money on an enclosed hood or Cool Tube. You can take warm air from underneath more effective adjustable open hoods by just placing the duct underneath the hood where it sucks out warm air in conjunction with an inline fan, Though really if you suck the heat from the top of the tent or closet it works just as well, if not better.

Basically what I'm saying is that if you have cabinet or a tent a good inline fan replaces the air usually 45 times an hour. The heat inside the tent is radiant heat and the only way to lower radiant heat on an HID is to lower lumens which makes no sense. Using a cheaper hood open on both ends lets heat escape from both ends and travel up to the top of the tent/cab where it is sucked out. So really all you need if using a cab or tent a powerful fan, fans moving the air inside and a good cheap open hood for heat control.

Another thing I hear is you need "fresh air" from the outside. This is true only if you are unable to replace the air, it's to hot inside and need to bring cool air from outside, there are no people living inside. The inside of a occupied home has way more Co2 than the outside environment. In the northern latitude are Co2 is about 400 ppm outside. In an occupied home, condo, rental whatever it's 800+ So the air from inside is actually better for plants than outside.

These are just some things I see all the time that are unnecessary.

Cool tubes allow you to place the plants closer to the bulb. When you are using a small HPS like a 400 watter with a ScroG it makes a huge difference because the plants can be within inches of the light.

A little shameless behavior in his past???

There is not much in the OP that I can agree with. Dealing with heat in enclosed spaces is all about the math. The temps in my space are constant regardless of whether or not the 400w HPS is on or off. Can you tell me why? I'll answer for you, no you can not because I will not give you the variables necessary to solve my heat equation. Handling heat in a grow room is no different than a data center or a rack of servers. FWIW I'm an IT professional and many of the skills I learned over the last 20+ years are directly transferable to growing.

No go sell crazy somewhere else, we all filled up here.

No go sell crazy somewhere else, we all filled up here.

Click to expand...

Nice! lmao

OP is on the money. The biggest mistake I see people make in venting is not taking advantage of the fact that heat rises. Cool air in the bottom, hot air out the top, it's really that simple. Too hot, increase flow.

If you can have a cool tube inches from the plants. You can have the light inches from the plant as long as you have the right airflow taking the heat away. The reason why most plants burn is because they're hit with radiant heat. So you're saying that cool tubes take away radiant heat which in HIDs is basically the light. When the air moves away from the plant it moves away whether it's in a tube or not.

Bonzi Lighthouse said:

A little shameless behavior in his past???

There is not much in the OP that I can agree with. Dealing with heat in enclosed spaces is all about the math. The temps in my space are constant regardless of whether or not the 400w HPS is on or off. Can you tell me why? I'll answer for you, no you can not because I will not give you the variables necessary to solve my heat equation. Handling heat in a grow room is no different than a data center or a rack of servers. FWIW I'm an IT professional and many of the skills I learned over the last 20+ years are directly transferable to growing.

No go sell crazy somewhere else, we all filled up here.

Click to expand...

Bonzi Lighthouse said:

A little shameless behavior in his past???

You come off as an A-hole narcissist. I'm sorry if you are autistic and can't understand reality unless it's in the form of equations. I have no heat issue's so I don't need your help. So, exactly what don't you understand. All I'm telling people is that what you, if you are so intelligent and have been growing forever, should already know. The temperature 8 inches from a bulb in a cool tube is the same as the temperature 8 inches away from a bare bulb because the light itself is what gives off warmth and whatever that light hits are variables, in which, affect the ambient temperature. There of course are many variables, virtually none of which is corrected by the use of a Cool Tube. The reason why I know this is because I have a buddy who had heat issues, 98f inside 80f outside the tent. So he bought a 6" dia. Cool Tube ran 6" duct end to end to each side of the tent with a inline 250 ft/hr. fan for his grow. It didn't help. We put a thermometer 8" away from the bulb in the cool tube roughly 6" away from the actual glass tube, we than did the same thing with the bare light and their was no difference in temp we also measured the temp in a shaded corner, still no difference. I than, with his terror, slashed 6" up from the bottom creating flaps, I used the inline with a duct vent sucking directly under an open bottom lid, and took away all together the much smaller fan he was using for venting. We got the heat down from 98 to 83. ........ Oh, and I have no idea where your stapler is.

Click to expand...

@ OP. Honestly man. I think you just did something in your expirament wrong somehow and maybe didn't notice it?...

All I'm sayin man, is if cooltubes, or ventalated hoods were worthless, then why the FUCK would people be willing to down $100 on them?... lol, If they didn't do anything different than a bat-wing reflector does, why would so many people pay that much more for them, and why would so many people be using them?... Just sayin man, I have a ventalated hood. When I have my fan attached to the hood and ON it's a whole lot cooler in there, and if I have my fan NOT hooked up to the hood and sucking 'cool' air across the bulb. You see, this is the reason it cools things down. Because it is pulling cool air across the blub. In comparison to someone not venting their hood and then all that heat is just chillin right around the bulb.

IMHO, cool tubes/hoods work fantastically! Otherwise people wouldn't be paying $100 for the damn things.....

phyzix said:

Cool tubes allow you to place the plants closer to the bulb. When you are using a small HPS like a 400 watter with a ScroG it makes a huge difference because the plants can be within inches of the light.

Click to expand...

^^^ This man..... SO much of this! lol

skunky33 said:

You come off as an A-hole narcissist. I'm sorry if you are autistic and can't understand reality unless it's in the form of equations. I have no heat issue's so I don't need your help. So, exactly what don't you understand. All I'm telling people is that what you, if you are so intelligent and have been growing forever, should already know. The temperature 8 inches from a bulb in a cool tube is the same as the temperature 8 inches away from a bare bulb because the light itself is what gives off warmth and whatever that light hits are variables, in which, affect the ambient temperature. There of course are many variables, virtually none of which is corrected by the use of a Cool Tube. The reason why I know this is because I have a buddy who had heat issues, 98f inside 80f outside the tent. So he bought a 6" dia. Cool Tube ran 6" duct end to end to each side of the tent with a inline 250 ft/hr. fan for his grow. It didn't help. We put a thermometer 8" away from the bulb in the cool tube roughly 6" away from the actual glass tube, we than did the same thing with the bare light and their was no difference in temp we also measured the temp in a shaded corner, still no difference. I than, with his terror, slashed 6" up from the bottom creating flaps, I used the inline with a duct vent sucking directly under an open bottom lid, and took away all together the much smaller fan he was using for venting. We got the heat down from 98 to 83. ........ Oh, and I have no idea where your stapler is.

Click to expand...

You added a cool tube and temperatures didn't drop? Clearly you installed it incorrectly or measured the temperatures with some bizarre method. If the thermometer is in direct light it's not accurately reading ambient temperature, perhaps that is what you did?

While were on the subject....

I'm about 2 weeks into my first grow. Im using a 400 MH and a 600W HPS in air cooled lamps. I have a 400 cfm inline fan pushing the hot air through the lamps and out of the room. I have a few small fans pumping fresh air as well. With all this said, I'm consistently reaching temperatures above 90+ and today around noon i was all the way up to 94. It only drops to the low 80's when the lights are off.

Is this too hot for my ladies? Are there any cost efficient ways to cool it down?

Thanks,
Rug

Rugganug said:

While were on the subject....

I'm about 2 weeks into my first grow. Im using a 400 MH and a 600W HPS in air cooled lamps. I have a 400 cfm inline fan pushing the hot air through the lamps and out of the room. I have a few small fans pumping fresh air as well. With all this said, I'm consistently reaching temperatures above 90+ and today around noon i was all the way up to 94. It only drops to the low 80's when the lights are off.

Is this too hot for my ladies? Are there any cost efficient ways to cool it down?

Thanks,
Rug

Click to expand...

Yes that is too hot! I noticed what your problem is right away!..... You said you have a 400 CFM fan *PUSHING* the hot air through your lamps and out of the room..... You ALWAYS ALWAYS ALWAYS want to *PULL* air through you lamps.... So you have it like this now right (the arrows [>>>] are pointing the direction the air is flowing) - FAN>>>LIGHT>>>LIGHT>>>Hot air exiting room>>> correct??? How you SHOULD have it is like this LIGHT>>>>>LIGHT>>>>>FAN>>>>>sucking the hot air out of the room. It is VITAL that you always *SUCK* or *PULL* air to deal with heat. Never *BLOW* or *PUSH* air. that is worthless... Does what I'm saying make sense?

Rugganug said:

While were on the subject....

I'm about 2 weeks into my first grow. Im using a 400 MH and a 600W HPS in air cooled lamps. I have a 400 cfm inline fan pushing the hot air through the lamps and out of the room. I have a few small fans pumping fresh air as well. With all this said, I'm consistently reaching temperatures above 90+ and today around noon i was all the way up to 94. It only drops to the low 80's when the lights are off.

Is this too hot for my ladies? Are there any cost efficient ways to cool it down?

Thanks,
Rug

Click to expand...

Make sure to always use negative pressure. That means pulling air instead of pushing it. A fan pulling hot air out the top of a box works better than the same fan pushing cold air in the bottom.

For efficient cooling use large holes for passive intake, and have as much suction out of the box as possible.

I'm a brand noobster, been reading up and all for the past 3 weeks. I seem to have a heat problem. I have a DS120 Jardin, with both bottom flaps open, and also the (input) fan sock open near the bottom of the cabinet. Using a 600w HPS lamp, and a fan sucking the air out the top sock hole into the exterior (room with the window open). Exhaust fan is 100mm, 145 m/h, capable of a little more at the second speed -which I'll try tomorrow. Temp inside the cabinet away from the lamp is around 79F. , but the temp where the plants would be approx is around 91F. The lamp is about 24" away from the top of the table where the cuttings will be. So, that's too hot for them. I have to somehow draw that heat away from the area below the lamp. I'm going to try bringing the trunking down to one end of the lamp, and try and suck the air across the lamp. It should help, but I can't help but think there must be a better way. I have another cyclic rotating fan blowing across the hot area, but so far it's had little effect. Perhaps if I closed the two lower end inlets, and took the trunking from the lower sock hole and positioned that at the other end of the lamp, that would help? In effect, the only air inlet would be drawn across the lamp, and in theory, sucked up and out.. I think though, that warm air may accumulate in the upper area of the tent.... I can only try.
Temperature in the room outside is fairly steady at 72F.
The lamp is not really enclosed - it's has like a wrap around reflector. Just checked - it's a Growcontrol Star light kit. Oh.. I have a filter, but it's not yet fitted. So I can only imagine that will aggravate the situation.

This is a pretty basic problem, and I may well get bollocked - but I need to learn!

Thanks!

Fishwipe

LARRY FISHWIPE said:

I'm a brand noobster, been reading up and all for the past 3 weeks. I seem to have a heat problem. I have a DS120 Jardin, with both bottom flaps open, and also the (input) fan sock open near the bottom of the cabinet. Using a 600w HPS lamp, and a fan sucking the air out the top sock hole into the exterior (room with the window open). Exhaust fan is 100mm, 145 m/h, capable of a little more at the second speed -which I'll try tomorrow. Temp inside the cabinet away from the lamp is around 79F. , but the temp where the plants would be approx is around 91F. The lamp is about 24" away from the top of the table where the cuttings will be. So, that's too hot for them. I have to somehow draw that heat away from the area below the lamp. I'm going to try bringing the trunking down to one end of the lamp, and try and suck the air across the lamp. It should help, but I can't help but think there must be a better way. I have another cyclic rotating fan blowing across the hot area, but so far it's had little effect. Perhaps if I closed the two lower end inlets, and took the trunking from the lower sock hole and positioned that at the other end of the lamp, that would help? In effect, the only air inlet would be drawn across the lamp, and in theory, sucked up and out.. I think though, that warm air may accumulate in the upper area of the tent.... I can only try.
Temperature in the room outside is fairly steady at 72F.
The lamp is not really enclosed - it's has like a wrap around reflector. Just checked - it's a Growcontrol Star light kit. Oh.. I have a filter, but it's not yet fitted. So I can only imagine that will aggravate the situation.

This is a pretty basic problem, and I may well get bollocked - but I need to learn!

Thanks!

Fishwipe

Click to expand...

Very minimum to cool the 600w is about 200CFM. If your outside room is @ 72* then this will keep you at around 82*. Your not moving enough Air.

phyzix said:

Cool tubes allow you to place the plants closer to the bulb. When you are using a small HPS like a 400 watter with a ScroG it makes a huge difference because the plants can be within inches of the light.

Click to expand...

Took the words out of my mouth. +rep

Thank you Bonzi, for your very prompt and precise reply. I'll attend to the situation right now..

But wait!

The fan is is 145M/H ... which is 145 cubic metres per hour... and you're suggesting 200 cubic feet per minute? Am i reading this incorrectly? 200 cf seems an AWFUL lot of air to shift in a minute..

Fishwipe

LARRY FISHWIPE said:

Thank you Bonzi, for your very prompt and precise reply. I'll attend to the situation right now..

But wait!

The fan is is 145M/H ... which is 145 cubic metres per hour... and you're suggesting 200 cubic feet per minute? Am i reading this incorrectly? 200 cf seems an AWFUL lot of air to shift in a minute..

Fishwipe

Click to expand...

600w HPS puts out alot of heat.

To convert CFM to CMH use the folowing formula CFM X 0.03 X 60 = CMH

View attachment 1057599

LARRY FISHWIPE said:

Thank you Bonzi, for your very prompt and precise reply. I'll attend to the situation right now..

But wait!

The fan is is 145M/H ... which is 145 cubic metres per hour... and you're suggesting 200 cubic feet per minute? Am i reading this incorrectly? 200 cf seems an AWFUL lot of air to shift in a minute..

Fishwipe

Click to expand...

200 CFM isn't much at all, a $30 fan can do that. I use a 1000 CFM fan (rated at over 2000, but that's complete nonsense and I added a scrubber).

Changed everything up and sure enough already seeing comfier temperatures!
Noob mistake... imagine that!

Thanks for the much needed info

Rug

Yeah, I guess using a 400 watter it would be Okay. But for a 1000 the effects of a cool tube are minimal because the intensity of the light. Even with a cool tube you can't have a plant less than 10" from the light of you'll get bleached. Plants can only consume so much light anyway. I find it better to have plants 2 feet away over a larger area than 1 foot in a smaller area. The yield difference between a plant being 3 feet away and 1.5 feet away from a 1000 watt HPS is minimal. I actually have some of my best yielders on the outskirts of the grow.