Cooltube/Fan Question - Room Running Hot

[Riboflavin]

Hey all, I have setup a small tent with a 400 watt HPS and made a glass cool tube that goes over the bulb, this is connected via 4" ducting to a stanley blower fan and a carbon scrubber. I thought this would work a lot better but unfortunately it seems like a lot of heat is escaping through the glass, holding your hand under it is quite warm and ambient temps in the room can get up to 90

So here's my question, should I buy a bigger fan or a sealed hood to solve my problem. The fan I am currently using is around 265cfm I believe, however its been used for a while and undoubtedly lost some power. If I got say a 465cfm inline fan, do you think this would be a substantial amount of airflow to bring the temps down with the tube or do I need a sealed hood?

Thanks!

 

[JackTheGrower]

They can be so solar!

Serious they can warm up the ground.. However the air will cool the bulb and extend the life of it in such a closed space as a tube..

Myself I have 1500 watts in three tubes and let me tell you it was hot ground until the plants started shading things but I have to keep up on plant transpiration.

The answer if to provide cooler inlet air for your situation from what I read.

I pull from the box and an external source and blow in a closed system but, my ambient is cool air.. The relative heat is high as it's summer but the fresh air is cool.

So can you do better? Yes and no.. Yes if the fresh source air has the cooling power and no if you can't; in my opinion, if that light is warming surfaces that cannot cool with fresh air...

I always want to draw fresh air for the room from a low point such as closer to the ground as it will be cooler and Co2 will be better low anyway.

If I can be of any help let me know.

My lights are in my photos as is my room and garden.. Maybe that will help with ideas.. It's just that the radiation of the light is such an excellent thing and we will have to deal with the surfaces heating.

Jack

 

[sns_stealth]

id say you need the sealed hood and if you can adapt your fan(or get a new one) than I'd suggest going to 6" ducting. The 4" with a 400W HPS leaves VERY little room for air to pass around it which allows heat build up and be pushed out of your unsealed hood. the fan is prob. suffering because of this also.

 

[Riboflavin]

I could adapt 6" ducting to the sealed hood. Would this stop the heat leak?

With lights off the temps are very happy, low seventies. But with lights on, it just can't keep up.

 

[sns_stealth]

I could adapt 6" ducting to the sealed hood. Would this stop the heat leak?

With lights off the temps are very happy, low seventies. But with lights on, it just can't keep up.

all situations are different but it would defiantly help. its at least the cheapest of your options to see how much it will help.

is the hood "open" on one end or is there ducting coming in from outside the tent?

 

[DiscoBiscuit]

Ribo, not sure of the orientation and intake specifics so here's some info I found works best. Your intake, if passive should be 2x exhaust. Since you're running 4" duct, you need eight square inches of passive intake. I'll be happy to give more info but passive intake is usually the first place to check.

For the tube, it will run cooler if the assembly is set up with the bulb socket closest to the exhaust fan. The typical efficient setup goes something like this, assuming your filter is inside the cab/tent. Filter >Tube>Exhaust. It'll run a little cooler if the fan is as close to the tube as possible. That means the duct run off the exhaust side of fan will be longer. Fans push through duct just fine, as long as there's no scrubber or muffler to impede the pushed air. Another great way to cool that hot spot is to get a nice 5" pc fan. Install the fan so that it blows length wise between the tube and plant canopy. As heat generates, the fan will blow heat away form the canopy and it's much better than a stagnant spot that continues to heat as long as the cycle is on.

The bulb/canopy cooling fan will also reduce the heat buildup inside the tube. This means the air expansion from heat is less and the fan will remove it a little quicker. This also helps to decrease the on-cycle, heat build up.

 

[sns_stealth]

Ribo, not sure of the orientation and intake specifics so here's some info I found works best. Your intake, if passive should be 2x exhaust. Since you're running 4" duct, you need eight square inches of passive intake. I'll be happy to give more info but passive intake is usually the first place to check.

For the tube, it will run cooler if the assembly is set up with the bulb socket closest to the exhaust fan. The typical efficient setup goes something like this, assuming your filter is inside the cab/tent. Filter >Tube>Exhaust. It'll run a little cooler if the fan is as close to the tube as possible. That means the duct run off the exhaust side of fan will be longer. Fans push through duct just fine, as long as there's no scrubber or muffler to impede the pushed air. Another great way to cool that hot spot is to get a nice 5" pc fan. Install the fan so that it blows length wise between the tube and plant canopy. As heat generates, the fan will blow heat away form the canopy and it's much better than a stagnant spot that continues to heat as long as the cycle is on.

The bulb/canopy cooling fan will also reduce the heat buildup inside the tube. This means the air expansion from heat is less and the fan will remove it a little quicker. This also helps to decrease the on-cycle, heat build up.

 

[Riboflavin]

Thanks guys!

@DiscoBiscuit I have added a second passive intake as well as a pretty large fan pointed right up at the tube, I turned the lights on (tent is empty right now still testing) so we'll see how it goes. Any idea how long it will take to generate the 'full' amount of heat? Will it continue to heat up for 12 or 18 hours?

 

[Riboflavin]

Currently sitting at 84.1 degrees. Seems somewhat stable, would like to take it down a few more degrees though

Edit: looks like that was the high, its down to around 82 now Thanks everyone

 

[DiscoBiscuit]

Yeah Ribo, sounds like things are going in the right direction. Not sure how long the cycle will take two peak. Once it reaches peak, it should ride until off. A setup that doesn't peak indicates a tweak may be needed. 85 or less at the heat spot usually gives you much better growing potential than 90. Not sure if you can get temps lower but the low fan sounds like it's working. Seems it will push the slightly cooler air from the bottom of the grow area up to the hot spot. I can't really think of anything else but I'd give my left one for 82 degrees in flower, lol.

 

[Riboflavin]

Well I hope I'll be good to go here then

I have a little Tomato plant in there right now for testing, it seems to like it, lots of air movement now and temps never peaked over 84.4

You grow coco as well right? I got some bcuzz coco in a 50L bag, I was wondering if this needs to be flushed or if it should be good to go.

 

[DiscoBiscuit]

I've read it's good to flush, gets the pH stable. Never tried coco though.