Need some pro advice

A friend of mine has a closet...the flowering room would be 20"deep by 55" tall by 39" wide.

Is a 400w HPS going to be over kill?

a 250 watt light is enough and much easier to cool

Im not sure what to do cause the 400 doesnt cost much more than a 250...

you will gain more bud but that area needs to be cooled for sure,the 250 will do just fine though thats what i use two in a 4 by 6 floor by six ft high celing and i get wieght.and quality

How are u going to cool it, 250 400 mad heat off both, go with the 400 and vent the shade from out of ur box in thru shade to other side out ur box, go big or have to trim bottm parts cause to lil light to make it thru the canopy of weed

vdubb:
Can you explain in more detail what you mean?

Bugs bunny:
I think your right. The floor is about 3'x20", thats about 6sq.ft. From what I read you want around 40watts per sq ft.
6 x 40 = 240 watts So a 250 should be ok I presume.

WHat do you think about heat issues with a 250 in that space?
I already plan on setting up a small fan to move air around. Will I also need to vent air out?

Get a 400, its not that much heat, easily displaced with proper cooling. 400 will double your yield over a 250, lots more bang for the buck!

Heres a PIC of some Northern Lights I grew with a 400. Actually its two 400 HPS, but the total volume is 28"x45"x54"(D*H*W). Temps never exceed 80F from ambient 71F temps. Its only slightly larger than your space so a single 400 watt should easily foot the bill.

Ok. 400 it is!

Im also debating between a 175w mh system for 129 bucks or a t5 florescent for 70 bucks.