1k watt heat question..

Space is a 4 foot long, 3 foot wide 9 foot Tall.
Originally was gonna use this as veg room for outdoor,
Turning it into flower room.
1000watt will be dimmed to 50-60% ( whatever the lowest setting is on my dimmable ballast)

Going to have a 6in 430cfm fan in there
The fan is going to go
Carbon filter —-> hood ——>fan ——> out window.

With a 8in passive intake at the bottom,
The room where it’s going to be intaking from is a constant 73 degrees.

My concern is even with venting out the hot air the inside temps are going to be 83+

So I guess my question is how much heat does a aircooled 1000 watt hps @ 50% dimmed produce?

Thoughts?

73 f is just under 23c...

Why not run the light at 100%? I would assume that you would be able to keep the room temp at 33c (91F).

Lucky Luke said:

73 f is just under 23c...

Why not run the light at 100%? I would assume that you would be able to keep the room temp at 33c (91F).

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Huh? Litterally every thread I read about heat issues states that 85F is the max if not injecting C02 into the room.

Of course I will crank the light up to 75% or 100% if I can keep the temps below 85F

outdoor2018 said:

Huh? Litterally every thread I read about heat issues states that 85F is the max if not injecting C02 into the room.

Of course I will crank the light up to 75% or 100% if I can keep the temps below 85F

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Dimming a 1000w hps to 50%-60% is really not the way to go its totally inneficient.. you better use a 600w at that point which is more efficient.. yes i wouldnt go above 82-85F unless you use co2.. maybe you should try the opposite 8inch as exhaust and 6inch as intake to create some negative pressure and remove hot spot in your room.. you should be able to maintain the room with good temp at 100%.. maybe look at adding an AC working only with lights on.. there is different option.. but dont go above 82-85 maximum !

thing about temp, whats actually important is your canopy temperature. you want the surface of the leaves to be about 88 degrees, thats the optimal temperature for them to carry out their processes. under an h.i.d. light about 16 inches away, a room temp of 78-82 will put your canopy temp right in the target area. people who run leds have to run supplemental heat a lot of the time to maintain that canopy temperature.

and Vice is right, you'll get much better results running a 600 on full than a 1k dimmed down.

If you want to make this really work I would suggest you take advantage of your 9ft vertical height. This answer involves a ridonkulous amount of work but it is exactly what I would do in your cabinet (yes, 4 x 3 is a cabinet, not a room) and I have used this method before for very small 250w cabinets. Should work well for 1000 watts also.
Create a raised floor platform with particle board and polystyrene foam board. This raised floor will have 12” spaces between 2” x 6” support beams which are between the particle boards. The particle boards are sandwiched by foam boards.
The cross section of this raised floor is as follows: foam board , particle board, foam board, air gap, foam board, particle board, foam board.
Connect some galvanized vent adapters to feed the air gaps (through MERV 13 air filters) from a box which accepts the air filter and adapts to feed air into the void spaces of this raised floor. Make some holes in the floor (not too small to avoid excess frictio and not too few that you don’t equal the area of the intake vent) between where you plan on putting things.
Before making the vent holes in this raised plenum floor, make sure you could drill an equal amount of vent holes in another raised floor platform of exact size and construction. But this exact same platform is attached to the ceiling instead. This ceiling plenum with air gaps is fed through an equal amount of perforations as the floor platform and the air gap spaces act like air ducts which you will adapt to feed your carbon filter.
By doing this , you will have a true floor to ceiling air flow (completely vertical) which passes through the undersides of the leaves. This is how I ventilate small footprints. Heat rises naturally. Sure would be a good idea to make the air flow from bottom to top. Lots less friction when you do it like that.
You should also have more than one fan/filter for the sake of redundancy. Use a thermostat with probe cable to take outdoor temps and control (on/off not speed)the second fan when needed. Also, you need a 24VDC/VAC actuated damper on the intake register to control temps. Otherwise you have no real-time temp control. Some will tell you to put a fan speed control instead of an adjustable damper controlled by a thermostat and repeat cycle timer. But fan speed controls are not as reliable or effective as regulating the air intake through automatically adjustable dampers.
Did I mention that a fan speed controller will eventually break much much sooner than a damper actuator will?

outdoor2018 said:

Huh? Litterally every thread I read about heat issues states that 85F is the max if not injecting C02 into the room.

Of course I will crank the light up to 75% or 100% if I can keep the temps below 85F

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Well I get decent results at over that..no problems.


I think most people who say these things haven't grown in warmer temps or use fans...Like outside, air movement and transpiration is key.
People indoor grow in Australia and South Africa and we see peaks of 40 plus c (104F) at times.
Its not usual for me to see 35c (95f) in my tent in summer.

Lucky Luke said:

Well I get decent results at over that..no problems.
View attachment 4105624 View attachment 4105626 View attachment 4105628

I think most people who say these (lets face it low temps) things haven't grown in warmer temps or use fans...Like outside, air movement and transpiration is key.

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Like everything else.. its not a matter of if you can grow or not grow.. its about being optimal.. provide me with any source of information stating that over 85F plants love it and increase their photosyntesis and Ill support you but I dont think you will find anything to suggest that unless you are in a sealed room with co2.. its like RH people grow with 20% other with 70% they all grow.. but when you are within optimal range you get better results period. Try for yourself and then we chat again in a couple months when you come back and tell us about your best harvest to date! Happy growing

Viceman666 said:

Like everything else.. its not a matter of if you can grow or not grow.. its about being optimal.. provide me with any source of information stating that over 85F plants love it and increase their photosyntesis and Ill support you but I dont think you will find anything to suggest that unless you are in a sealed room with co2.. its like RH people grow with 20% other with 70% they all grow.. but when you are within optimal range you get better results period. Try for yourself and then we chat again in a couple months when you come back and tell us about your best harvest to date! Happy growing

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I'm not saying it is optimal. I'm not saying anyone is wrong. I'm not arguing the point with anyone.

I'm merely stating that you can in fact grow pretty decent cannabis over the temps some people say you must have. Dimming a thousand watt bulb to grow less bud due to not wanting a temp that Is perfectly fine to grow in would be a waste if time.
The biggest argument for lower temps seems to be bud density. I have found that with the temps I grow in that's not the case.

@Tim1987
I think you grow in some higher than ideal temps in your room to for decent results. Is that the case?

I use a light rail in my current grow. My 1kw Hortilux HPS is 13-16" from the top of my canopy RH 51% and temps at 22c - 24c at the top of the canopy/, 22c ambient room temp

Lucky Luke said:

@Tim1987
I think you grow in some higher than ideal temps in your room to for decent results. Is that the case?

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Absolutely man. My weather is bipolar 12 months of the year.
You cant get them outside early. You also have to harvest early because of the fluctuations.
Powdery mildew is a huge problem where i am.
Yields are inferior too.
But inside i dont have to run aircon.
Ive had temps above 35 for several hours in heat waves, and they wrere fine. Didnt fluff out or bolt at all.

Roger A. Shrubber said:

thing about temp, whats actually important is your canopy temperature. you want the surface of the leaves to be about 88 degrees, thats the optimal temperature for them to carry out their processes. under an h.i.d. light about 16 inches away, a room temp of 78-82 will put your canopy temp right in the target area. people who run leds have to run supplemental heat a lot of the time to maintain that canopy temperature.

and Vice is right, you'll get much better results running a 600 on full than a 1k dimmed down.

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I run my room opposite as you
I keep my canopy temp below the ambient room temp. I pay attention to VPD .


Some of you are running higher temps then me with out CO2 , and I run 1200-1300
Finding the right balance is key your each setup.

If you watch your temps and stop thinking 100 is ok, you might be using cans n bottles , to show relevant size , vs a bic lighter .

Agreed. Not optimal.
But if you can still get them as thick as your arm, who cares about a tiny loss in yield, if the quality is there?
I think quality is the most important thing. To say you cant get quality in those temps is a lie.
Thats our point.
It saves money in the long run, because of power cost, and you still get the quality at the end.
I wanna smoke that shit of lukes right now. It looks tasty as fuck.
I still wanna affordably grow my weed in the summer. Commercial weed is so dry here around christmas. Because the big hunchos turning a profit make a loss in their yields.
But personal use, I say bring it on.

BigHornBuds said:

I run my room opposite as you
I keep my canopy temp below the ambient room temp. I pay attention to VPD .


Some of you are running higher temps then me with out CO2 , and I run 1200-1300
Finding the right balance is key your each setup.

If you watch your temps and stop thinking 100 is ok, you might be using cans n bottles , to show relevant size , vs a bic lighter .

Click to expand...

i keep my veg room about 75 with a rh of 60, the flower room can hit 80, thats about as high as it goes. i keep the rh in there at 45, so the median condition is about 78 with an rh of 45...not in the green, but its worked for me for a while now, and i've never gotten pm or bud rot.

Roger A. Shrubber said:

i keep my veg room about 75 with a rh of 60, the flower room can hit 80, thats about as high as it goes. i keep the rh in there at 45, so the median condition is about 78 with an rh of 45...not in the green, but its worked for me for a while now, and i've never gotten pm or bud rot.
View attachment 4106109

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Your numbers will work . The whole post wasn’t detected at you , just the 1st part.
once I’ve started to pay attention to the VPD I’ve only seen improvement, along with having my top canopy temp below ambient temp.

Roger A. Shrubber said:

i keep my veg room about 75 with a rh of 60, the flower room can hit 80, thats about as high as it goes. i keep the rh in there at 45, so the median condition is about 78 with an rh of 45...not in the green, but its worked for me for a while now, and i've never gotten pm or bud rot.
View attachment 4106109

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Yep, yep

Tim1987 said:

Agreed. Not optimal.
But if you can still get them as thick as your arm, who cares about a tiny loss in yield, if the quality is there?
I think quality is the most important thing. To say you cant get quality in those temps is a lie.
Thats our point.
It saves money in the long run, because of power cost, and you still get the quality at the end.
I wanna smoke that shit of lukes right now. It looks tasty as fuck.
I still wanna affordably grow my weed in the summer. Commercial weed is so dry here around christmas. Because the big hunchos turning a profit make a loss in their yields.
But personal use, I say bring it on.

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Good enough is good enough for some .
You might be surprised at the increase in yeild when you pay attention to all factor.
Providing the right conditions will also make your plants finish faster . (Or in the time that they should)


Good enough is not good enough for me
I want it right, each to there own .

BigHornBuds said:

Good enough is good enough for some .
You might be surprised at the increase in yeild when you pay attention to all factor.
Providing the right conditions will also make your plants finish faster . (Or in the time that they should)


Good enough is not good enough for me
I want it right, each to there own .

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Maybe, though if you're paying more for ac than plant you can fit in your space, its a loss.
If the quality is there, but you have to run ac to fill the space, and dont gain a dollar, but lose several, its a big loss. Ain't a way around it.
Winter is an absolute dream here though. Heating costs me fuck all in comparison, and the yields probably 20% more. But only by the amount of flowers. Not the quality.

BigHornBuds said:

I run my room opposite as you
I keep my canopy temp below the ambient room temp. I pay attention to VPD .


Some of you are running higher temps then me with out CO2 , and I run 1200-1300
Finding the right balance is key your each setup.

If you watch your temps and stop thinking 100 is ok, you might be using cans n bottles , to show relevant size , vs a bic lighter .

Click to expand...

I'm guessing last part was a dig at me? Could be wrong but I'm on my first cuppa of the day.
I wasn't posting pics to say "hey I'm the best grower with the biggest dick". Look at the quote I quoted when I posted the pics.

Plenty of posts of beer bottles as reference in lots of my pics in the Aussie thread, Scrog thread and even some smaller colas and plants with a beer bottle in Skunk and Shit thread.(in sig) In fact ill post plants that are doing well and plants that I'm struggling with. Its all fun and to me its not a compition.

Ive been growing (on and off) since the late 80's (mainly outside). Have grown in the Kimberly dessert and still achieved decent buds. I aint the best grower and I don't know it all but its gotta be damn hot with no air movement for cannabis to struggle.

My point is people can and do grow in warmer climates indoors and they grow decent bud without AC or a sealed room and CO2. Wrapped that you have a great environment to work with but I and many others don't have that luxury. And they can easily achieve 1 g per w using a single light source doing it.