[shannonball]

hi everyone, new to this site. came over from Rollitup. We just finished fixing up our shed to grow (legal state of MA). We have a timber lighting 900 watt Vero 29c's LEDs in an 7x4'5" room 8' high.
We are going to install a fresh air intake using a Hepa filter in a filter box on a hurrican 8" inline fan. We will have an exhaust fan in the gable for outtake, no filter required as the smell is not going to be noticed due to no neighbors. We will fans blowing both plants and the heat sinks on the leds. What size exhaust would you recommend and does our setup sound alright and what should we change? thanks shannon

[zeke99]

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[Kwigybo]

I'm having real heat issues in my tent and I can't figure out why. Tent is 2'x4'x7' (56 cubic feet). Light is a 400w hps in a cooltube with a 5 inch exhaust fan. It's exhausting through a hole in the floor (one 90 degree bend) and is rated at 165cfm.

Second fan is a 4 inch axial hooked up to a 12inch carbon filter and is rated at 80cfm. And two passive intakes.

Ambient temps are around 68 but after a few hours with the light on it's up to 84 and just keeps climbing.

Any help would be greatly appreciated. Thanks.

[Snook]

6" cool tube w 5" fan??

what type of fan is exhausting the light and how far is it from the light to the exhaust hole in the floor and is it pushing or pulling air through the light? Pics would help.

[OldPhart]

Originally Posted by Kwigybo

I'm having real heat issues in my tent and I can't figure out why. Tent is 2'x4'x7' (56 cubic feet). Light is a 400w hps in a cooltube with a 5 inch exhaust fan. It's exhausting through a hole in the floor (one 90 degree bend) and is rated at 165cfm.

Second fan is a 4 inch axial hooked up to a 12inch carbon filter and is rated at 80cfm. And two passive intakes.

Ambient temps are around 68 but after a few hours with the light on it's up to 84 and just keeps climbing.

Any help would be greatly appreciated. Thanks.

I see two issues, as Snook pointed out, the size of the fan/duct on the light sounds suspect. The other issue is the axial fan on the carbon filter. An axial fan isn't well suited to producing static pressure required to move the air through a carbon filter. I wouldn't be surprised if your 80cfm fan is only moving 25cfm with the filter attached. I would be looking to get at least 120cfm (2 air changes/minute) out of the tent. Depending on the efficiency of the cooling of the light, you may be able to reduce this requirement.

I would also insulate as much of the ducting carrying the heat off the lamp as possible.

[zeke99]

Originally Posted by Kwigybo

I'm having real heat issues in my tent and I can't figure out why. Tent is 2'x4'x7' (56 cubic feet). Light is a 400w hps in a cooltube with a 5 inch exhaust fan. It's exhausting through a hole in the floor (one 90 degree bend) and is rated at 165cfm.

Second fan is a 4 inch axial hooked up to a 12inch carbon filter and is rated at 80cfm. And two passive intakes.

Ambient temps are around 68 but after a few hours with the light on it's up to 84 and just keeps climbing.

Any help would be greatly appreciated. Thanks.

FWIW, according to the CF Group (Can-Filter), a single 90 degree bend can reduce the airflow by a few percentage points.

[Kwigybo]

Thank you Snook, OldPhart and Zeke for the responses. Much appreciated.

*The cooltube is actually 5" (not 6") so it matches the fan size in diameter.
*The type of fan exhausting the light is a mixflow tt 125 (5"). Link
*The distance from the light to the exhaust hole is roughly 7.5 feet.
*The light exhaust fan is situated about 1 foot above the floor hole and is pulling air through the cooltube/ducting.
*And I'm using 5" insulated ducting.

I think you're right OldPhart that the Allvent axial, though a high quality product, simply isn't designed for the pressure required to work with a carbon filter. I have another axial which is 5inch, so I wonder if I swapped the mixflow to the carbon filter and put the axial as the light exhaust if that would improve the results.

I'll try to get some pictures.

Once again, thank you for your replies.

[Snook]

Originally Posted by Kwigybo

Thank you Snook, OldPhart and Zeke for the responses. Much appreciated.

*The cooltube is actually 5" (not 6") so it matches the fan size in diameter.
*The type of fan exhausting the light is a mixflow tt 125 (5"). Link
*The distance from the light to the exhaust hole is roughly 7.5 feet.
*The light exhaust fan is situated about 1 foot above the floor hole and is pulling air through the cooltube/ducting.
*And I'm using 5" insulated ducting.

I think you're right OldPhart that the Allvent axial, though a high quality product, simply isn't designed for the pressure required to work with a carbon filter. I have another axial which is 5inch, so I wonder if I swapped the mixflow to the carbon filter and put the axial as the light exhaust if that would improve the results.

I'll try to get some pictures.

Once again, thank you for your replies.

5" cool tube, I never noticed a 5" one before but see that 'china' make them. Its hard to screw up a glass tube but if you bought the fans from them too, could be they are less affective than advertised.. we all start out 'el cheapo', so did I but over the years, its become clear to me that that is not always the cheapest way to go because, at least I, had to buy mobetta 'parts' a second time. GL bother.

[Ruskointhehouse]

Originally Posted by Kwigybo

I'm having real heat issues in my tent and I can't figure out why. Tent is 2'x4'x7' (56 cubic feet). Light is a 400w hps in a cooltube with a 5 inch exhaust fan. It's exhausting through a hole in the floor (one 90 degree bend) and is rated at 165cfm.

Second fan is a 4 inch axial hooked up to a 12inch carbon filter and is rated at 80cfm. And two passive intakes.

Ambient temps are around 68 but after a few hours with the light on it's up to 84 and just keeps climbing.

Any help would be greatly appreciated. Thanks.

why are you exhausting via the bottom of the grow? heat rises - vent from the top man.

[Granger2]

Forget axials. The do little actual air movement. Good luck. -granger