HPS venting questions!!!!!

I am looking to get either a 400 or 600 watt HPS for my walk in closet grow, but I do not have the ability to vent at this time. It is a fairly large space at 8x10x8. Ambient air temps stay at 69-74 degrees and the closet does have an a/c vent. So my question is what size HPS could I comfortably run without venting? Thanks for any help!!

you need venting to bring fresh air into the room as well as removing heat.are you sure you cant cut a hole up into the attic or down into basement or even into next room?
I used to grow in a barn in winter & a 400 keep the 4x4 room at 70 when the outside air was 32.I used a PC fan running 24/7 for air exchange.
an incandesent light will throw almost as much heat per watt so to give you an idea about temps,put 4 100 lights in the room and see what the temp is after 6-8 hrs.

you need to cool the light. if you dont a room at 70 will be over 100 in 15 min. and i believe everyone on this site with a 400 watt or larger light will tell you the same thing. you cant buy a better electric heat source than a hid grow light

hang your light and mark where it goes and cut a 6inch round hole at each end off the light in the ceiling. run 3ft of 6in ducting from each end of light and into the ceiling. then go in your atic and attach a 6in inline fan so it blows into the light and back into attic.

Since neither a 400 watt light nor a 600 watt light will light an 8x10 area anyhow, and assuming you really can't drill holes, I would build a 4x4 or 5x5 box within the closet and vent out of that box, leaving the closet door open so that air can exchange. You will be utilizing your light better and if you have company over you can simply close the closet door.

regrets just made a great point. or a grow tent set up might work best for you.

I have a homebox xs tent and a 400w hps. It's 2 x 2 x 4 ft and the hottest my tent gets with the ambient room temperature between 70-75 is about 85 degrees. This is also with a 465cfm fan pulling air out.

I just put lots of fans

Thanks for all the replies!! I guess I will see what I can do to vent!!

regrets said:

Since neither a 400 watt light nor a 600 watt light will light an 8x10 area anyhow, and assuming you really can't drill holes, I would build a 4x4 or 5x5 box within the closet and vent out of that box, leaving the closet door open so that air can exchange. You will be utilizing your light better and if you have company over you can simply close the closet door.

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Well the 600 hps does 8x8 and I have 500+ watts worth of CFL's to use for side lighting. Thanks for the box idea, I might look into that!

I have had this exact problem... So, being a contractor.. i easily ran an A/C duct into the room.... although this worked, it only work while the a/c was running.. my upstairs was frigid as hell...

I switched to CFL lighting, so i didn't get that heat; which was stunting my plant, that i was getting. this worked very well.... I wish i could of gotten a decent air-cooled reflector and also afford the cost of the duct fans, the ducting itself, and the etc. that go with that... I simply did not have the money... I am in no way saying that CFLs are better, but with money/space/heat in certain situations, they are the best choice....

I have a 1k hps in a different grow room that has ample space and ventelation and man, for a soil grow, they grow fast as hell

Theanswerto1984is1776 said:

I Ambient air temps stay at 69-74 degrees and the closet does have an a/c vent. So my question is what size HPS could I comfortably run without venting? Thanks for any help!!

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with that temp, and since it will obviously be decreasing, i would say an unvented 400w hps.. maybe even 1k w, will be fine... just make sure you have a fan blowing upwards toward the bulb at all times.. this blows some of the bulb heat upward, away from the plant