Air Cooled Lights...how much airflow is required.

[Haggis123]

Hi guy's, hoping someone can answer my question.

I am planning on using 2 x 250w HPS in a double length cool-tube in a micro cab that measure's 1m tall x 1m wide x 50cm deep.
I was planning on buying a duct fan with an output of 350m3hr, to pull through a Phat Filter and blow throgh the cooltube and then exhaust out the cab......do you think that 350m3hr would be enough to keep the tube cool ??

I have saw the post where there is a chart relating to air flow originally made by Cali Grower...I think....the chart only relates to open hood lights and not air-cooled.


I was also considering possibly using two smaller fans.
1 for independent cooling of the cooltube and the other for scrubbing the air in the cab.
It's obviously a bit more complex to set up due to space constraints.....but can be done.
What do you think would be best ???

 

[Guest]

Hi haggis,

Can you explain a little more about your fan? Do you know the cfm rating? I am unfamiliar with 350 m per 3 hr. That would equate to roughly 117 m per hour or 2 m per minute. 3 feet in a meter.....I would say this fan will not properly cool your bulbs.

I am a little unsure about your fan, perhaps it is 350 cfm per 3 hours? In this case it would be powerful enough. Can you tell us a little more about it?

That seems like a lot of light for such a tiny space. Without too many bends in the ducting, you will want a fan that can exhaust the area of your space (1m x 1m x 50 cm) two to three times per minute. With it being such a micro climate, its very sensitive to both heat and cold. It would heat up very fast without proper ventilation and introduction of cooler air. You will need an intake drawing fresh cooler air into the cab to offset the heat that will build up. With proper cooling, it can be done.

Just be careful you aren't drawing that hotter exhausted air back into the cab as "cooler intake air". For instance, if the box is in a room or closet. Make sure the exhausted air is either cooled before its reintroduced into the cab, or that it is exhausted away from the room completely.

 

[Haggis123]

Yat Yat, many thanks for the reply.

The fan is rated at 350 cubic metres per hour. I was planning on a Solar and Palau TD350 fan.
I would also plan on using a mix of PC fans and passive for intake.
I understand what you are saying about drawing back in..the hot air, that has just been exhausted.
I have designed the cab to exhaust and draw in...air, from either end of the cab to try and eliminate this.

 

[Guest]

Nice that fan should do the job, if its getting warm in that micro climate just boost the a/c if you can or increase intake. I have a good feeling with the appropriate intakes and exhaust combined with adequate a/c this can be possible. I see you want to use a phat filter. I assume being stealth is a major concern? You can always make a diy carbon filter, as they can take the shape of just about anything. perhaps will allow you to make it even a bit smaller than the version phat filter makes.

hope this post goes thru, the last few replies I tried to give wouldnt let me exceed 10 post per 24 hr. just wanna help! haha

 

[jordas]

what size is the inlet/outlet of the S&P fan your interested in as your number must be a european style number.......they are different in usa..........take a look here:

http://www.hvacquick.com/spfnconfig.php?fm=td

also, seems like maybe a bit of over kill on the lights.....
500w for just over 6 sq ft??........that works out to nearly 75w per sq ft...
500w in a micro cab is alot of heat..........to use that amount would most
likely require the use of a/c or some other form beyond just fans......unless the ambient temps are fairly low.......like its located in a basement.......
perhaps a pair of 150w bulbs or just a single 250w would work out better?

 

[Haggis123]

Thanks for the replies guy's....

Yat Yat, I already have the Phat Filter....that's why I plan on using it.
I agree a custom made DIY filter can be better made to fit in with what space you have to work with....but the Phat'ty is there why not use it. Thanks for the suggestion though.

Jordas, here's a link to the fan I plan on using...http://www.tlc-direct.co.uk/Products/SLTD350.html It has 125mm "5 inch" inlet & outlet.

I agree 2x250w in a micro situation is a lot of light and possibly a lot of heat, the reason I am considering this is....I already have the double length cool-tube that I bought sometime ago for another cab....that I had to put on hold.

I think that the heat put out by the 2x250w light may come in handy.

I live in the U.K and plan on having this cab out in the garden, using one of these http://www.outstanding-keter.com/catalog-in.asp?cat=11&pr=2&num=21 as the disguise for the stealth operation.

I think that during the winter months and most of our dreadful summers that we get here...lol...that with a combination of these http://www.tlc-direct.co.uk/Main_Index/Heating_Index/Slim_Heat/index.html#Slim_Heat slimline heaters that I plan on installing and the heat coming from the lights that that will keep my box at a reasonable temp.....hopefully.

I have considered using 150w bulbs but I already have 2x250w digital ballasts that were bought for the same project as the double length cool-tube. So rather than shelling out more cash, I am trying to stick with what is already available....but...once again many thanks for the thoughts and concerns.

So anyone got a chart or anything...that shows how much airflow is needed to cool a sealed air-cooled reflector with varying light wattages or simillar??

 

[Guest]

Haggis,

You are smart to work with what you have! I think you will do just fine. As for airflow needed to cool a sealed room , that can be a tricky question. There are many variables to be taken into account. It would be dependent on ambient temps, and temp of intake so long as you are exhausting properly. Especially with such a small mirco environment. Its not just the airflow that cools. Airflow helps cool, but its the temp of ambient air and intake that will cool your space. So long as there is adequate airflow, you can cool the space. cooling it is another task though

does this make sense?

 

[Haggis123]

Yes mate that makes sense.

Because this unit will be sited outside the ambient temps will obviously vary....but I think all should be o.k.
I would maybe just have to shut the grow down for a 2-3 month period in the peak of summer...if temps got too hot....but here in the U.K that may not even be required if we have a simillar summer to the one just past...lol.

Thanks for the input YatYat.

 

[petemoss]

I think it'll work, Haggis. I'm cooling a 250 with a 100 CFM S&P fan and happy with the result. Canopy temps about 4F above ambient. Your fan translates to about 206 CFM.
And I'm using a Bake-Around tube less than 4 inches in diameter. I imagine your tube is 5-6 inches -much more air flow. At first, I was disappointed with my setup because temps under the light were 9F above ambient. But after moving my Lumatek ballast outside the cab, it was 5F cooler! So I'd suggest remoting your ballasts.

 

[Haggis123]

Thanks Pete good to know that you are controlling your temps o.k with what you got, very encouraging.
Yeah, the cooltube is a 5inch diameter one.