Air temp for venting lights.

Green Giant · Jun 3, 2013

The other night I was in the garden and stood up underneath a hps and man was it hot!!!

So that got me thinking about venting/cooling with air, but what air and what temp should this air be???

I can assume I do not want to pull outside air into the garden, but do I want to use air conditioned air that's aprox 70* I would think the hot bulbs would not like this!!!

What is your thoughts on this??!

ttystikk · Jun 3, 2013

Green Giant said:
The other night I was in the garden and stood up underneath a hps and man was it hot!!!

So that got me thinking about venting/cooling with air, but what air and what temp should this air be???

I can assume I do not want to pull outside air into the garden, but do I want to use air conditioned air that's aprox 70* I would think the hot bulbs would not like this!!!

What is your thoughts on this??!

I think that is a waste of money. Don't cool the air used to cool bulbs- just send it back outside. The temp rise between inlet and outlet is what you're trying to maximize- but spending money to actively cool this equipment is not going to net any measurable return.

If outside air is just too hot, then use air from your air conditioned house. This worked great for me when I lived in the Deep South.

Green Giant · Jun 3, 2013

ttystikk said:
I think that is a waste of money. Don't cool the air used to cool bulbs- just send it back outside. The temp rise between inlet and outlet is what you're trying to maximize- but spending money to actively cool this equipment is not going to net any measurable return.

If outside air is just too hot, then use air from your air conditioned house. This worked great for me when I lived in the Deep South.

I understand not cooling the air used for the lights, if I pull air from my house/basement it will be at around 65-70*.

Will this cause any problems with such a hot light bulb? Will condensation form, ect???

ttystikk · Jun 3, 2013

Condensation happens when hot moist air encounters a cool surface below local dewpoint. Light bulbs are anything but cool! BTW, this is also why you do not place an Icebox or other cold water to air heat exchanger in your hood venting system. These often shed droplets of water. Water droplets + hot light bulb = no bueno.

Green Giant · Jun 3, 2013

ttystikk said:
Condensation happens when hot moist air encounters a cool surface below local dewpoint. Light bulbs are anything but cool! BTW, this is also why you do not place an Icebox or other cold water to air heat exchanger in your hood venting system. These often shed droplets of water. Water droplets + hot light bulb = no bueno.

So I won't have an issue pulling much cooler air into the hood?

If that's the case could I use outside air in the winter months to cool the rooms and lights??

ftwendy · Jun 3, 2013

If the dewpoint in the grow room is above the temp of the air from the basement, then you won't have to worry about rain forming on the inlet tube. If rain forms, just make a simple gutter from some mylar and direct the condensation/rain into a funnel that drains into the root zone. You are distilling pure water... make use of it!

ftwendy · Jun 3, 2013

If you plan to use super cold winter air to cool your room, be sure to PUSH the cold air in with your fan on the outside of your grow. This way condensation will not form on your fan. Add a good damper on the grow air side and you're golden.

Outside air->-Fan-->--damper--------->------duct->--grow room---->>>

ttystikk · Jun 4, 2013

ftwendy said:
If you plan to use super cold winter air to cool your room, be sure to PUSH the cold air in with your fan on the outside of your grow. This way condensation will not form on your fan. Add a good damper on the grow air side and you're golden.

Outside air->-Fan-->--damper--------->------duct->--grow room---->>>

I pulled my air through the hoods all winter and had no problems. Condensation certainly formed on the outside of the hood venting, but that should not affect the bulbs inside. I don't recommend pushing air through hoods to cool them, ever.

ftwendy · Jun 4, 2013

Good points. Tho I was talking about cooling the room. I agree that air should be pulled through hoods, however pushing air into a grow space is just fine.

As for the condensation on the outside of hoods -- I have always been concerned about drips falling on the buds, so I catch them before they do. cheers, ftw

Miggs · Jun 4, 2013

I draw air from outside to cool my lights year round in the North East.

ftwendy · Jun 4, 2013

Me too. Super cold air causes unexpected dew sometimes, thus the mylar gutter... but a fan controller is the real solution for worry free year round use of outside air.

There is a point when the outside air is too cold and begins to change the lamp's performance. Hopefully somebody chimes in with an explanation about that, as I know nothing specific.

Green Giant · Jun 4, 2013

ftwendy said:
Me too. Super cold air causes unexpected dew sometimes, thus the mylar gutter... but a fan controller is the real solution for worry free year round use of outside air.

There is a point when the outside air is too cold and begins to change the lamp's performance. Hopefully somebody chimes in with an explanation about that, as I know nothing specific.

This is what I was worried about.

SeaLMeaT253 · Jun 4, 2013

I have a xxxl hood and have been using the air from inside my house to pull through my hood for over a year with no problems, it typically stays in the 65-70º range in my home also. I can hold my hand to the glass on the hood in the middle of on time and its hardly warm to the touch. I hope this helps.

Green Giant · Jun 4, 2013

SeaLMeaT253 said:
I have a xxxl hood and have been using the air from inside my house to pull through my hood for over a year with no problems, it typically stays in the 65-70º range in my home also. I can hold my hand to the glass on the hood in the middle of on time and its hardly warm to the touch. I hope this helps.

That would be nice. My summer outside temps can reach 90+* and winter time can be 0-30*.
I keep the house temp around 72-73* but I don't want to vent my a/c air outside through the lights

ftwendy · Jun 4, 2013

GGiant: get a fan speed controller before it gets too cold again. When it gets cold, dial down the fan speed.

It is fine to use the warm/hot outside air all summer long... no need to waste the air you paid to chill. Even if it went above 100deg outside, you would still be fine using that hot air to keep your lights cool.

ttystikk · Jun 5, 2013

ftwendy said:
Good points. Tho I was talking about cooling the room. I agree that air should be pulled through hoods, however pushing air into a grow space is just fine.

As for the condensation on the outside of hoods -- I have always been concerned about drips falling on the buds, so I catch them before they do. cheers, ftw

The reason I recommend that people don't ever push air into spaces to cool them has nothing to do with the size or use of the space; the fact that gas (air) is being compressed (pushed) by a fan (even more heating, due to friction) means that it will always be warmed up. If this air is to be used for cooling, pushing the air around goes a long way towards defeating the purpose!

Pulling air reduces its pressure- and therefore temperature. Thus, the exhaust fan, hopefully mounted high in the warmest part of the room, is the fan really doing the work of cooling.

The only time I push air to cool it is when I'm shoving air through an Icebox air to water heat exchanger. I push warm air into the box, thus warming it further and increasing the temperature difference between air and water, thus boosting the exchanger's efficiency.

Green Giant · Jun 5, 2013

ttystikk said:
The reason I recommend that people don't ever push air into spaces to cool them has nothing to do with the size or use of the space; the fact that gas (air) is being compressed (pushed) by a fan (even more heating, due to ) means that it will always be warmed up. If this air is to be used for cooling, pushing the air around goes a long way towards defeating the purpse!

Pulling air reduces its pressure- and therefore temperature. Thus, the exhaust fan, hopefully mounted high in the warmest part of the room, is the fan really doing the work of cooling.

The only time I push air to cool it is when I'm shoving air through an Icebox air to water heat exchanger. I push warm air into the box, thus warming it further and increasing the temperature difference between air and water, thus boosting the exchanger's efficiency.

The reason I wanted to push air in was so I dident pick up any smell from my rooms if I had some leaks in my hoods. I did not plan on filtering this.

ttystikk · Jun 5, 2013

Green Giant said:
The reason I wanted to push air in was so I dident pick up any smell from my rooms if I had some leaks in my hoods. I did not plan on filtering this.

Yeah, that's a good reason. What worked here was wrapping the flexible ducting in shrink wrap plastic and tapping the seams on the hoods and duct flanges. Solves the problem, makes your sealed hood system work that much better, and less heating from any source means less cost getting it out of your growroom.

ftwendy · Jun 5, 2013

ttystikk said:
The reason I recommend that people don't ever push air into spaces to cool them has nothing to do with the size or use of the space; the fact that gas (air) is being compressed (pushed) by a fan (even more heating, due to friction) means that it will always be warmed up. If this air is to be used for cooling, pushing the air around goes a long way towards defeating the purpose!

Pulling air reduces its pressure- and therefore temperature. Thus, the exhaust fan, hopefully mounted high in the warmest part of the room, is the fan really doing the work of cooling.

The only time I push air to cool it is when I'm shoving air through an Icebox air to water heat exchanger. I push warm air into the box, thus warming it further and increasing the temperature difference between air and water, thus boosting the exchanger's efficiency.

I also have an active exhaust, tho I hear what you are saying about the increase in heat and pressure. To say nothing of the heat the fan introduces from cooling itself... interesting points again. Thank you

Herb Forester · Jun 7, 2013

ttystikk said:
The reason I recommend that people don't ever push air into spaces to cool them has nothing to do with the size or use of the space; the fact that gas (air) is being compressed (pushed) by a fan (even more heating, due to friction) means that it will always be warmed up. If this air is to be used for cooling, pushing the air around goes a long way towards defeating the purpose!

Pulling air reduces its pressure- and therefore temperature. Thus, the exhaust fan, hopefully mounted high in the warmest part of the room, is the fan really doing the work of cooling.

The only time I push air to cool it is when I'm shoving air through an Icebox air to water heat exchanger. I push warm air into the box, thus warming it further and increasing the temperature difference between air and water, thus boosting the exchanger's efficiency.

I just installed fans and ducting to vent my new AC box, and can witness to this wholeheartedly. I tried both methods, positive pressure made a huge efficiency difference, not in a good way. I was trying to avoid overheating my blower motors with the exhaust by installing them on the intake side, but suddenly the compressors couldn't keep up as they had in the original pulling configuration.

Does anyone have experience with just how hot inline fans can operate before wear or failure becomes an issue? I use redundancy in situations like this to avoid catastrophic failures, but not sure it will help much if both fans are roasting hot during lights-on.

Air temp for venting lights.

Air temp for venting lights.

Green Giant

ttystikk

Green Giant

ttystikk

Green Giant

ftwendy

ftwendy

ttystikk

ftwendy

Miggs

ftwendy

Green Giant

SeaLMeaT253

Green Giant

ftwendy

ttystikk

Green Giant

ttystikk

ftwendy

Herb Forester

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