Grow light room temp effects

[Bassman59]

I'm in the finalization stages of my grow room. All that's left is the final choice on light and cooling.

While I understand grow lights will cause heat, I have yet to find how much heat (ranges) can be expected from certain types of lights at given distances and room size effects.

Currently the room I'm in stays at 79 degrees using central AC in the lovely Nevada desert. Obviously I can drop the temps (ambient) at a cost.

I'm building my own grow room within this spare room. It will probably end up being about 5' x 5', within a 10' x 10' bedroom. Basically just framed in poly/mylar unless I step up for a tent, but that's not in my current plan for my first DWC grow of 8-10 fem seeds from Nirvana.

The current plan is 600w MH light. Adding cfl's at needed locations as the need arises.

So now I need to figure out how much real cooling I need. Will I need a in-line exhaust fan (and obviously venting it out of the room)? If so, how big is really needed? Is some of this hype? Will 2-3 strategically placed room fans do the job?

Let's face it, you can spend $50 - $300+ on an inline fan before adding the requisite ducting, filter, hangers, etc. What if a $75 unit could do the job but being the newbie you are the store sells you a $200 unit claiming that's what we need?

I have yet to see one, but a possibly cool idea for all forums users is a thread creating such information. Things needed to create a rough guide for users could be (add to the list if you think of anything):

1. Room size.
2. Light size/type (wattage, MH, HPS, LED etc)
3. Avg distance from plants - light on temp - lights off temp @ distance
4. Avg room temp - light on temp - light off temp
5. Inline exhaust CFM
6. Fan on temps as above
7. Fan off temps as above
8. Room floor or desk type fan info and results of use.

With enough people adding in their own personal grow room information as above we could come up with realistic information, compiled in easy to read formats.

In the meantime, how much cooling do I need? !!!!!!!

 

[YardDog35]

Good to hear you have seeds coming from Nirvana, Bassman!

There are so many variables when it comes to grow rooms its hard to nail down exactly what the temps will be in yours. I had to do some trial and error in my small space to get my temps dialed.

If you can exhaust out of the room your space will be in, you should be just fine.

You can either, A: Exhaust through your light hood and out of the room. Pulling the warm air from your space, through your light and out. If the walls of your space are flimsy this could cause them to implode some, and you will need a carbon filter. Or, B: Have your light hood intake and exhaust separate from your space. Ducting an intake from outside the space and exhausting out of the room. This should eliminate the need for a filter, but you will need to exhaust your space using computer fans or small fans of some sort. Put them on top of the space with passive vents on the bottom.

Hope that makes sense...I ramble when medicated.

Don't skimp on the inline fan, it is a must if you are running a 600w. 6" or 8" depending on what hood you are going with. An oscillating fan in the space will be needed as well.

 

[Bassman59]

Thanks for the response dog.

Ya I understand what your saying.

Now if we could say, with avg samples of 10 people here using 600w lamps, in a 25sq ft area they saw temps at x degrees above ambient y (avgs) w/o fan.

3 were using xyz cfm inline exhaust out of room fans and saw temp dips y degrees.
5 used....etc etc.
you get the point. From this we could have a more better understanding and more than likely get the right equipment the first go around and not waste too much on wrong stuff, too weak of products, or items of overkill. I'm sure there's going to be some point of diminishing return on exhaust fans where the increase of exhaust reduces the temps by a lower and lower percentage.

BTW, I hate that you mention it's an absolute must for the inline fan. another damned expense.

 

[YardDog35]

Plus rep my friend, for your determination and careful thinking

I hear ya...if there was such a thread with those comparisons I could have saved cash. Being the noob I was when I started (I'm still a noob, don't get me wrong) I thought I could get away with a cheap fan from a Depot store. Then I had to buy a bigger 'cheap' fan...then a cheap booster fan. Add in the ducting and parts as you mentioned, needless to say in my venture to avoid the $100+ inline fan I spent more in a matter of months.

I'm not sure how rural you are or if you're in a city but Craigslist (hope that's chill with the mods..) is a great place to score used grow equipment as long as you're careful. I've bought and sold locally with great success, good way to save $$$

Can't wait to see your garden up and running

 

[TorturedSoul]

A 600-watt MH will be awesome for vegetative, but will run hotter than a 600-watt HPS. Consider switching when going to flowering phase.

Suggest separate ventilation/ducting for the light and the room in general. Sealed reflector, draw air in from outside of the GR, through the light, and back outside. It won't have a smell (if everything is properly sealed), so you won't need a carbon filter for that. Vent the GR itself as needed - when running a separate vent setup for your light, you won't have near the heat to deal with in the GR, which means you can vent less - either at a lower constant CFM or in bursts which might make CO2 supplementation feasible - and less venting coupled with lower vented air means the GR carbon filter will both work better and last longer.

There are insulating covers for several of the different air-cooled reflectors which will further help you separate the light's heat from the GR. There is also insulated ductwork and/or double-wall type-B gas vent ductwork. Both of those should also help with noise-control if that is a concern.

Consider changing the shape of the GR to a rectangular one, which would allow you to use one 600-watt light on a light-mover. That would allow you to keep the light closer to the plants without subjecting them to constant bombardment (so to speak) and the mover will allow you to make up the footprint that you'd lose by dropping the light. And... If you are in a location that has cold winters, you could always stick the mover in the attic and add a second 600-watt light (making them both stationary) in the colder months without having to redesign the GR. Then, when hotter temperatures return you can go back to the single-light on the mover.

Should allow you to do the best you can year round.