I am on 18/6 in a 12' by 12' upstairs room. Recently I've been buying larger fans to accommodate the heat but I'm having problems with ducting/exhaust sizes. All my old fans have 4" openings for exhaust and I bought hoods with 4" exhaust holes. I've started been buying inline fans with higher cfm, recently bought one around 700cfm with 8" exhaust holes, but all my hoods only have 4" openings. Right now I use downsizing connectors to exhaust heat from my hoods which are 4" to my 8" fan. Even with this more powerful fan the temps are still way too high in this small room. The inline fan exhausts 2 hoods with 1000w bulbs (one MH and one HPS right now). In addition, I also have 2 smaller fans (not inline, 300 - 400cfm i think), one which exhausts only one other hood and one which just exhausts from the room in general. The air in comes from outside (a problem on 80 degree days like yesterday...) and vents out into the house and/or attic space. With summer here, even with these 3 fans there is no way I can run all 3 lights without the temps getting up to 100 degrees F. I can't even really run 2 when it's up to high 80s or 90s. Would new hoods with 8" or even 6" exhaust openings help at all? Does anybody have any ideas how I can get the heat down? Any ideas would be greatly appreciated :confused:

ac?????????????????????????????????

I have thought about using AC, and I might, but I'm way too high on my power load for that circuit. Plus, I'm trying to keep the power bill down for money reasons and also not too look to conspicuous. But it might just come to that....

Here is the problem. If the fresh air temperatures are 80-90 degrees you are not going to get the temp any lower no matter how much air you move through the room.

Agreed. Are you in a situation where evaporative cooling might be useful? I think that if your airflow is sufficient the plants shouldn't mind higher temperatures too much, should they? The other issue is humidity, and again, if you've got good airflow that shouldn't be too much of a problem. I've noticed a marked difference in behavior of my outdoor plants if there's too much humidity (the leaves curled under).

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Ron Paul doesn't deliver babies.
He reads them the Bill of Rights until they crawl their way to freedom!

whats evap cooling........i am intersted....

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"the more herb man smoke the more babylon fall" Robert Nesta Marley

Go with a portable A/C something under 10,000 btu--they use 5.5 to 8 amps--the delogh. line is pretty good.
Dr. VonDankenstine

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DR. VonDankenstine

Do you know what a swamp cooler is? It's air being passed over water (in a swamp cooler the water flows over lots of fins, something like a radiator), and in a DRY environment the water evaporating provides a heat exchange. It's why we sweat -- evaporative cooling. In this case I'm thinking that passing the air flow over the water (if we're talking about a hydroponic design) could help to cool the whole room, rather like aquarists do when they install muffin fans in aquarium hoods. Otherwise something like a chiller would be necessary, and that's as cost-effective as an air conditioner.

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Ron Paul doesn't deliver babies.
He reads them the Bill of Rights until they crawl their way to freedom!

A trick I used to sleep at nights may work. This was back before I had no AC.

Take 3 one gallion milk jugs and freeze them get a pan large enough for 1 jug put the jug in the pan and the pan in front of a fan.

When that jug melts put it back in freezer and put froozen jug in it's place.

Then keep rotating them as they melt. If it's really hot you may need more then 3 jugs. This trick can keep an avg. size room nice and cool. But a grow room does start with more heat. Good luck hope this helps.

Have you considered locting the ballasts remotely ? Might be esier to deal with the heat. They say dont run more than 25ft of wire to the lamp to avoid starting problems but it has a lot to do with the condition of the ignitor.