400 watt 2x4x5 heat question

Hello RIU,

I was wondering how much heat is emitted from a 400 watt HPS and/or MH bulb on a digital ballast. Using a 2x4x5 grow tent with mylar interior. The ballast has a 10' cord from ballast to socket, so the ballast will be housed outside of the grow tent to keep any heat it may emit out.

Couldn't afford a cool tube, so how hot will the 400 watt bulb get? I plan on using a 6" duct booster fan at the top of the tent and ducting to blow out the hot air, and passive intake is built in to the box. Will this keep temps low and fresh air in the tent? Any helpful suggestions would be appreciated.

tent http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=330536094186&ssPageName=ADME:L:OU:US:1123#ht_2913wt_905

It all depend's on the ambient general temp's in your house so if it get's hot in the summer in your place it could be dicey but with only a 400w you shouldn't have any worry's especially with the 6" on there. If you can afford it get a vortex.

what kind of reflector do you have? I have a 400w cool tube from htg supply. if you havent checked them out, you might find a good deal on just a reflector.

JP

the reflector is just a generic batwing type.

This cooltube at HTG is $100: http://www.htgsupply.com/Product-CoolTube-6in-Reflector.asp

Much too pricey for me after costs already spent, but low temps NECESSARY not an option, I know.

With no ventilation whatsoever, what do you think temps in the box would be?

How bout with the 6" 160cfm duct booster?

shit with no air moving temps will get over 100 ..(fast)!!.. slap this set-up in there.. http://htgsupply.com/Product-GrowBright-4in-Inline-Fan-&-Carbon-Filter-Combo.asp

You will have to vent one way or the other for sure. You need an active exhaust and passive intakes. The standard 6 inch duct fan wont be enough but you can use it and expect 90 degree temps. get you a 6 inch clip on fan and have it moving air around. Fresh air exchange is needed. get the air moving then sucked out by the exhaust. plus its great for the stems to have moving air. you dont want to blow them away, just a tiny vibration is all thats needed to encourage thick stalks.

JP

imma for sure ventilate, just wondering if the 6" duct booster would be enough, but sounds like not. I already plan to have an oscillating fan on the plants to help their growth. If you had less than $50 but wanted to keep temps at the right level( 75-78F? ) what would be the best you could do? Or is that even possible? Sounds like it might not be, a powerful cfm fan is expensive.

how many and what size vent holes does the tent come with? You may be able to use several duct fans in place of one large one.

JP

Vents: two 6" round, two 8" round, two 4" round, three 19 1/2"x2 3/4" rectangular

If i had to work with 50 bucks id get another duct fan and put one in each 6 inch hole. Its likely to get you in the high 80's with two of them going. when you can afford a cool tube it should only make it cooler in there.

JP

aight secured a fantech fx8 481cfm 8" fan, could I just make a DIY carbon scrubber and call it a day for ventilation/temp control on the box?

Will i need anything else to pull the hot stale air from the 2x4x5 cab with a 400watt hps and batwing? Will the fan be able to create enough negative pressure to keep cool air coming in from the passive intake grills on the side of the box? I will have an oscillating fan in the cab as well to move the fresh air around if it is being sucked in.

And how loud would you say this fan gets? Super loud? Hope not.

Stick a $14 home depot buct boosting fan in one of your vents and you should be fine. I would recommend putting it in one of the top vents blowing out - passive intake is fine. Your tent is only 40sq ft so an 80 cfm duct boosting fan will empty the air twice a mintue - should be totally sufficient until ambient summer temps go up.


/edit didn't see your last post. 481 cfm is way over kill for that area. get a fan speed controller and set to the lowest it'll run. I use a 440cfm fan for my 4x4x6.5 tent at the lowest setting and it sucks inwards due to presure. Passive intake and that fan willo be enough - now you just need a carbon filter. The small ones are only $40 - might just consider buying one than DIY.

Fan is LOUD. Again get a dimmer for it and you'll cut the energy bill and the noise. You can also mount inside of an insulated box.