Zandor, Karmaxul, exhaust fan advice?

[mountainman]

Ok, spring is definitely here and it's time to vent my light outside. I've got a sunleaves reflector and I need to mount a fan that I can easily duct outside and easily mount to the hood. What can you recommend that the Home Depot carries? I'm hoping for something that won't take too much messing around to get it working.

Also, Is it worth while to put either some plex or glass over the light to help with heat transfer? Would plexi glass work, or would it melt under a 400 watter?

[karmaxul]

I have used plexi glass but it is not as clear as regular glass. It is easy to cut sure but if a bulb was to explode would it burn? I would get plexi glass because it is easier to cut and at present I'm broke, but it is not the best way to go. I don't vent my lights I insulate my hood so no heat excapes. Make them air tight and use a/c to control temp. Thats just me. I have read in other posts the like a 265 cfm is the way to go for a 400 watt, but Zandor would really know alot more then me.

Whats the average temp in the room?
How big is the grow space?

[BlueDragonSmoke]

an AC is the ticket...cool the whole room and your light will be happy

[Zandor]

Plastic glass may bubble and discolor or even melt down if the temperature gets out of control. Single strength glass can be cut to fit by HD and will not cost you a bunch of money. Double strength glass is better only because it's easer to handle. Pick up some silver furnace heat tape to seal the edges of the hood to keep the air moving through the hood and not vent into the room. A Dayton blower works but they are a little noisy you can have HD order inline vent fans as long as the vent pipe run is not to long the inline fans can work.

It's better to push the air through a hood then it is to pull it through....fyi

[mountainman]

Well, we've got A/C, however it's not warm enough to run a unit without freezing the condenser. I live on the top floor of my building, though, so we get everyone else's heat, and for some reason everyone here really really likes their apartment super hot, even in the spring. Plus, the A/C is a room unit that's in the living room, not my bedroom. Money can be saved if the heat is just vented straight from the light to the outside. That way you don't have to cool that hot air, you can just dump it straight outside.

As far as the plex, I'm basically in the same situation. I can't dump more money into the system right now, so plex is cheap, and super easy to cut with a table saw. If it were to burn, it wouldn't be good for it to fall on the plants, but the products are harmless, just water and carbon dioxide. And apparently, the melting point is reasonably high, about 140 degrees celsius.

Karmaxul, as far as the insulating, I'm somewhat skeptical about how well that actually works. The reason is that when the hood and light reach static thermodynamic equilibrium with the surrounding air, the heat flux out of the system into the air will be constant. For insulation to work, the bulb would have to be a constant temperature heat source. But isn't a bulb more likely to be a constant heat flux source? To be a constant temperature heat source, it would need to have a temperature sensor built in to adjust the current going to the bulb.

[mobay]

http://www.littlegreenhouse.com/accessory/vent.shtml

[mobay]

http://www.littlegreenhouse.com/fan-calc.shtml

[turtle420]

It's better to push the air through a hood then it is to pull it through....fyi
No shit... for real?!

I thought it was the other way around... For real?!

I'm re-thinking a couple of things...

[Zandor]

No shit... for real?!

I thought it was the other way around... For real?!

I'm re-thinking a couple of things...

Yes for real. Pulling the air there is restriction or back pressure so unless the fan can pull like 3 times the air it may not get up to full speed and that will cause heat it's self in the motor you need to deal with. Pushing the air the motor is up to full pull and the backpressure works in your favor to exhaust.

Think about that for a moment.....it will come to you. :thumbsup:

Thanks for catching the seed sales and mom sales today too btw. :dance:

[BukDatAss]

Damn that was good to know but now I gotta go fix a lot of crap:mad: thanks for that advise.