bh2285

Hi..... This is my first real indoor setup that i have built. I have done some out door growing but it never seems to work as planned. So i have decided to go with indoor. Heres The supplies i have got..
1. Grow bow made from MDF ply wood in small walk in cloest (4x2x5 inside of grow box) painted white on inside with 2mm thick mylar everywhere.
2.400w HPS vented light with 2 fans one 210cfm inline hurrciane fan on intake side of light and on exhuast side of light a 65 cfm computer fan from radio shack running a 4" duct out of the box and out of the closet into the attic-no heating form the light is going it to the box or cloest.
3.Box cooling has 2 fans both 85 cfm radio shack computer fans one intake and one exhaust(exhaust hooked to 4" ducting to carbon filter)

I am having major problem trying to keep the setup cool its seems to always go up, i have only got it to hold like 91 degrees and it was only on for 8 hours.
I can not think of anything else that i can do to help this stay cool. If anyone has any ideas or any short please respond and tell me your ideas i need them i spent lots of money on this stuff and i need it to work in this area.
Also does anyone know if the 400w HPS hold a constant temp. or how hot does it get at its hottest point or does that depend on the bulb?HELP IF YOU CAN PLEASE!!!THANKS FOR YOUR TIME.

Chief Lakanukie

[quote=bh2285]
3.Box cooling has 2 fans both 85 cfm radio shack computer fans one intake and one exhaust(exhaust hooked to 4" ducting to carbon filter) QUOTE]

I'll take a shot...

I don't think that a computer fan has the balls to pass air through the carbon filter............

Easy enough to find out (if your grow isn't too stinky yet),,,, just disconnect the filter, and see what happens to the temps....

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anchorage1

[quote=bh2285]Hi..... This is my first real indoor setup that i have built. I have done some out door growing but it never seems to work as planned. So i have decided to go with indoor. Heres The supplies i have got..
1. Grow bow made from MDF ply wood in small walk in cloest (4x2x5 inside of grow box) painted white on inside with 2mm thick mylar everywhere.
2.400w HPS vented light with 2 fans one 210cfm inline hurrciane fan on intake side of light and on exhuast side of light a 65 cfm computer fan from radio shack running a 4" duct out of the box and out of the closet into the attic-no heating form the light is going it to the box or cloest.
3.Box cooling has 2 fans both 85 cfm radio shack computer fans one intake and one exhaust(exhaust hooked to 4" ducting to carbon filter)

I am having major problem trying to keep the setup cool its seems to always go up, i have only got it to hold like 91 degrees and it was only on for 8 hours.
I can not think of anything else that i can do to help this stay cool. If anyone has any ideas or any short please respond and tell me your ideas i need them i spent lots of money on this stuff and i need it to work in this area.
Also does anyone know if the 400w HPS hold a constant temp. or how hot does it get at its hottest point or does that depend on the bulb?HELP IF YOU CAN PLEASE!!!THANKS FOR YOUR TIME.[/QUOTE I don't know if this will work for you in your space, if you have the room to put it in. i had the the same size room. it is in a crate that is 2x4x5 and i also could not keep the temps belo 90. i bought a 85 dollar goldstar window ac unit and cut a hole in te box and now my temps stay at 73 to 80. good luck anch1 peace

Dday

Get yourself some 2 litre plastic bottles. Fill 'em most of the way with water and put 'em in the freezer. Put them next to your box's air intake and play around with the numbers until you're getting temps in the mid 80's.

Then get some mdf [or whatever] and build a box to enclose that number of bottles [between 2 and 4 should do it] as tightly as possible [that way they heat up slower and the ice stays cooler for longer]. Put some plastic sheeting in the bottom to take any condensation from the outside of the bottles. Then drill a hole in one side of the box big enough to hook up to your intake [directly if you can - just bolt the smaller box onto the side of the grow box - or alternatively via some ducting] and some smaller holes in the other side(s) so that you're still getting decent airflow while losing the minimum of cooling outside of the grow box. You want to keep the ice bottles as insulated as possible.

Job done... just replace the bottles when the ice melts. You might have to do that once/twice a day, but it's a nice cheap solution even if it's a stopgap while you sort out something else. If it works well enough you can just stick with that. Most people check their plants once a day anyway so if you do that, you can switch the bottles over then.


D

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bh2285

Thanks guys for all the help....I added that 4th fan to the exhaust of the light yesterday and i didnt give a test run till about 10:00 last night and when i got up this morning(at 7:00) is was holding(i think) around 79 degrees so i think i might have fixed the problem some how. But it still has to stay on for another 9 hours so i have no idea if it is going to work or not. But if it does not work im going to give that ice idea a try becuse i already thought or a cheap window unit....I was thinking about just puttin the unit on a shelf in the cloest but i was thinking about it more and decided that it would expel hot air out of the back of the unit and cause the cloest to get to hot..maybe im wrong? Thanks for all your help everyone...i will post pictures if anyone wants me too.

Mr.Bogart

Computer fans are even worse than that! I set up a 30CFM computer fan to ventilate my grow box. With the door closed, it has only to pull through two 5" x 4" louvered vents - one from the outside to the grow chamber, and one from the grow chamber to the grow box's attic, which is where the fan is mounted. The fan's CFM plummets when I close the door. Not only that, the noise goes way up.

Bottom line: If it has propellor blades, it's no good for pulling or pushing air through anything. I guess it's fine if you have a VERY open intake - or a similar fan on the intake - but you're right on: It can't pull jack through a carbon filter if it can't even pull through a louvered vent.

To push or pull through resistance (like a carbon filter), you need a centrifugal blower (such as what I'm replacing my fan with: the Sunon PMB1212PLB2-A).

Pufnstuf

If you have room you could put an insulated cooler (poke some holes in the top) in with the plants full of dry ice, it reduces temp slightly and has the added bonus of filling the space with CO2. With the fans blowing it should help disperse the CO2 so it stays at a reasonable level. Also the stuff is pretty cheap but may not be practical for the entire grow. I've actually never tried it but my bud (no pun intended) swears by it and I've smoked his crop and had no complaints at all.

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bh2285

I have two 85 cfm fans on the the intake and the exhaust of the grow box...I have not actually hooked up the carbon filter to the exhaust yet because theres no smell. I think the cfms will drop about half or more when i add the filter so that leaves me with about 35 to 40 cfms maybe.. The cfm calculator says that i need at least 40 cfms to exchange the air once every min.. I think that i should be good on this but not for sure....Tell me what u think if you want. Thanks

Mr.Bogart

I think your actual CFM is much, much less than the fans are capable of in free air. A four inch duct, especially the flexible vinyl "dryer duct", restricts the airflow by an amazing amount. For example, I once hooked up a 120 CFM fan to a 2' length of straightened 6" flex duct. The resulting air flow was minimal. I replaced it with a centrifugal blower and all was fine. Similarly, I found a 30 CFM computer fan can't even pull air through a louvered vent!

Any fan using angled blades to push the air only really works if you have little resistance on the input and output. This means venting directly to the room, and having a very free intake. So I think you need to get a centrifugal type blower (such as most bath fans) for your exhaust. Also, it would really help to run 6" duct from box to attic - or, if it's short, you can probably get away with 4" smooth aluminum flex duct.

If you're not clear on how to identify a centrifugal blower, let me know.


P.S. To find your required CFM, take the lamp wattage, multiply by three, and divide by the target temp rise to get the CFM requirement. Say your box is in a 70 degree room. You want the box to get no hotter than 85 degrees inside. 400 x 3 / (85 - 70) = 80 CFM.

bh2285

Yeah so when i finally got around to hooking up the carbon filter to the 85 cfm radio shack computer fan the grow box just started to over heat once agian...So heres what i did tell me if u think this will work?? I took the 210 cfm hurriciane inline fan that was cooling the light on the intake side, off and swapped it with one of the 85 cfm computer fans( so theres now a 85 cfm on the intake side of the light and a 65 cfm exhausting the light in to the attic. Does any one know about how many cfms it takes to cool off a enclosed light? Then i took the 210 cfm inline and made it so it was sucking the air out of the grow box for the exhaust and then through the carbon filter. It felt like the air coming out of the filter had increased alot so im thinking that might fix the problem. But i guess my real question is do you think that will be enough to cool a 400w hps with those little ass radio shack fans?