CMH 315W vs budget Kingbrite QB for cold climate

[OldMedUser]

Thanks,

Usually about 12-18 degrees tops (if you're american that's like 55-65ish). I think I will have to find a solution with a space heater or convince my wife to let me leave it upstairs.

Once you have a light going in a tent it'll be a lot warmer in there. Just going to get cold air entering when you open the flaps to work on your plants. How big is this basement? Mine is more of a large underground crawl space that's 10x30 and about 7.5' tall. My grow room was built by the previous owner as a cold storage room and had shelves all around. It's about 7x9x6.5'h. Two walls are just OSB board on cement and two are insulated 2x4 stud walls with a heavy wooden door I installed a dead bolt on. smooth, painted cement floor that drains to a sump in case of spills.

When I first went to view the place that room sold me. lol I had a bunch of plants in my grow room in the garage at my place in town. Got the place for 50G and sold my dump in town for 32G. Tiny lot in town with a POS '74 12x65' mobile home and 20 x 20 insulated/heated garage. This place, 7.5 acres, 1990 16x80' mobile with 6" walls with 17x34x10'h heated shop, my 15x12' mancave with same size mudroom and a 20x35' carport all attached as one unit. The old guy started asking 175G then kept lowering the price until my wife saw it in the paper and we scooped it up for 50. Stuck in the middle of nowhere but can just do whatever I want and there's no one to complain. Shoot my guns, crank my stereo and grow lots of stinky pot to my heart's content. Two nice whitetail deer in the front yard yesterday. Dog near freaked out. lol

If you have space upstairs then you might be better off up there during the cooler months then you could always move the tent downstairs in the summer if the tent gets too warm. Bit of a PITA but with the wife helping should be easy enough. How about venting tho? Can you be cutting a vent hole to outside? For a 3x3 tent a 4" vent should be big enough. Wasn't for my room but I'll run 3 x 4 HPS or a 1000W sometimes so a lot more heat to deal with. There was 4" already but I cut a 6" hole in the stub wall to vent out under my shop. Has a metal flap vent on the outside. Like a dryer vent but bigger.

Environment is important for good growing especially in the flowering stage. Not such a big deal in veg I find. My exhaust fan has a home made almost RH/Temp and speed control on it so it only runs when needed. Thermostat on the heater so temps are steady day or night. Good circulation is a must so an oscillating fan is best. You might want to rig a shelf or something to hold a fan up over the canopy to move air around. Not sure how small you can get in an oscillating fan. I have a 12" going 24/7 to keep the air mixed up well. If you could find an 8" that would be enough.

I have enough lights and gear to do 4X the space I have now but plans to expand and I'm one of those guys who likes backups for his backups.

 

[Airwalker16]

The heat maintained inside the tent will depend entirely on how fast and powerful his exhaust is. A tip is to for certain, mount your driver to your fixture to bring that heat inside the tent if youre going to be needing more warmth.

 

[Airwalker16]

Once you have a light going in a tent it'll be a lot warmer in there. Just going to get cold air entering when you open the flaps to work on your plants. How big is this basement? Mine is more of a large underground crawl space that's 10x30 and about 7.5' tall. My grow room was built by the previous owner as a cold storage room and had shelves all around. It's about 7x9x6.5'h. Two walls are just OSB board on cement and two are insulated 2x4 stud walls with a heavy wooden door I installed a dead bolt on. smooth, painted cement floor that drains to a sump in case of spills.

When I first went to view the place that room sold me. lol I had a bunch of plants in my grow room in the garage at my place in town. Got the place for 50G and sold my dump in town for 32G. Tiny lot in town with a POS '74 12x65' mobile home and 20 x 20 insulated/heated garage. This place, 7.5 acres, 1990 16x80' mobile with 6" walls with 17x34x10'h heated shop, my 15x12' mancave with same size mudroom and a 20x35' carport all attached as one unit. The old guy started asking 175G then kept lowering the price until my wife saw it in the paper and we scooped it up for 50. Stuck in the middle of nowhere but can just do whatever I want and there's no one to complain. Shoot my guns, crank my stereo and grow lots of stinky pot to my heart's content. Two nice whitetail deer in the front yard yesterday. Dog near freaked out. lol

If you have space upstairs then you might be better off up there during the cooler months then you could always move the tent downstairs in the summer if the tent gets too warm. Bit of a PITA but with the wife helping should be easy enough. How about venting tho? Can you be cutting a vent hole to outside? For a 3x3 tent a 4" vent should be big enough. Wasn't for my room but I'll run 3 x 4 HPS or a 1000W sometimes so a lot more heat to deal with. There was 4" already but I cut a 6" hole in the stub wall to vent out under my shop. Has a metal flap vent on the outside. Like a dryer vent but bigger.

Environment is important for good growing especially in the flowering stage. Not such a big deal in veg I find. My exhaust fan has a home made almost RH/Temp and speed control on it so it only runs when needed. Thermostat on the heater so temps are steady day or night. Good circulation is a must so an oscillating fan is best. You might want to rig a shelf or something to hold a fan up over the canopy to move air around. Not sure how small you can get in an oscillating fan. I have a 12" going 24/7 to keep the air mixed up well. If you could find an 8" that would be enough.

I have enough lights and gear to do 4X the space I have now but plans to expand and I'm one of those guys who likes backups for his backups.

Not having neighbors, period, is the greatest one up of all.

 

[Rocket Soul]

Extracting from the bottom is another way of keeping things hotter

 

[end_of_the_tunnel]

Extracting from the bottom is another way of keeping things hotter

I wonder how efficacious a U-shaped plenum around bottom of grow area would be. In cool weather drawing out, and in warmer weather blowing out via such an arrangement. Just a thought, because vent hose blowing out on one spot can be problematical.

 

[OldMedUser]

Extracting from the bottom is another way of keeping things hotter

I really don't see how that makes a difference if there is lots of circulation in the grow space. It's like people saying to draw air from the top to reduce heat as hot air rises.

That makes sense if you have no fan(s) mixing the air up but with good circulation the air temp should be uniform from the floor to the ceiling so exhaust placement shouldn't matter.

It's like folks saying to run tubing to release CO2 above the plants because it's heavier than air and will fall on the plants. Maybe with static air conditions but the slightest movement of air it mixes right in. With that logic on a calm, still day heavier gasses would settle on the ground and suffocate us all. lol

I used to draw fresh air in from outside but when it's goes from -30C in winter to +30C in the summer it's problematic. Now I pull all my intake air from the greater basement area which never gets warmer than maybe 65F and no cooler than around 40F in the dead of winter. Much better.

I think I'd rather deal with it being too cool than too warm. No way I could grow upstairs in the summer especially in flowering. A guy can always drape blankets or otherwise insulate a tent to help keep it warmer too.

Then there's the issue of really low RH . . .

 

[OldMedUser]

I wonder how efficacious a U-shaped plenum around bottom of grow area would be. In cool weather drawing out, and in warmer weather blowing out via such an arrangement. Just a thought, because vent hose blowing out on one spot can be problematical.

I'm not sure I understand what you mean. My vent hose blows out in the same place since I installed it 10 years ago and I can't figure out what you mean by U-shaped plenum. "Plenum: a space or all space that is full of matter. a general assembly of all members esp: of a legislative body."

 

[Rocket Soul]

I really don't see how that makes a difference if there is lots of circulation in the grow space. It's like people saying to draw air from the top to reduce heat as hot air rises.

That makes sense if you have no fan(s) mixing the air up but with good circulation the air temp should be uniform from the floor to the ceiling so exhaust placement shouldn't matter.

It's like folks saying to run tubing to release CO2 above the plants because it's heavier than air and will fall on the plants. Maybe with static air conditions but the slightest movement of air it mixes right in. With that logic on a calm, still day heavier gasses would settle on the ground and suffocate us all. lol

I used to draw fresh air in from outside but when it's goes from -30C in winter to +30C in the summer it's problematic. Now I pull all my intake air from the greater basement area which never gets warmer than maybe 65F and no cooler than around 40F in the dead of winter. Much better.

I think I'd rather deal with it being too cool than too warm. No way I could grow upstairs in the summer especially in flowering. A guy can always drape blankets or otherwise insulate a tent to help keep it warmer too.

Then there's the issue of really low RH . . .

Not sure how it would work iin a tent but in openspace it made a lot of difference, like a whole heater. Also good for keeping rh up as less water in cold air in the bottom. But with a tent i cant really say.

 

[end_of_the_tunnel]

I'm not sure I understand what you mean. My vent hose blows out in the same place since I installed it 10 years ago and I can't figure out what you mean by U-shaped plenum. "Plenum: a space or all space that is full of matter. a general assembly of all members esp: of a legislative body."

I probably used the wrong terminology. Meant vent with lots of holes or outlets. The vent being in U-shape mounted at a suitable height to blow warmer/or cooler air at or just above rootzone. And covering three sides of grow, hence the U.

This video shows them mounted between valoya strips. Flexible mining/industrial type. Would not be any use for drawing air.

Metal ones.

Both of these examples are mounted at light/lamp level. The concept I had was for the mounting to be at a point where you could control or influence rootzone warming or cooling.

 

[OldMedUser]

The concept I had was for the mounting to be at a point where you could control or influence rootzone warming or cooling.

It's a bit hard to do that unless the lower section is sealed off a bit so the air doesn't immediately mix in. I already have something like that planned out for an addition to my grow room I'm still thinking about building. Would keep DWC tubs cooler using my cool basement air. Plants grown in pots of soil/soilless like warmer temps and are often too cool tho.

 

[Chip Green]

Even as an avid DIY LED enthusiast, I do not hesitate to endorse the 315 CMH unit.
I continue to achieve spectacular results with my collection of 315 CMH fixtures.

 

[Rocket Soul]

Even as an avid DIY LED enthusiast, I do not hesitate to endorse the 315 CMH unit.
I continue to achieve spectacular results with my collection of 315 CMH fixtures.

I absolutely agree, if you have problems keeping up with environment of leds CMH is awesome. I took us several cycles before led best cmh on a per area base. They also work quite alright in high temps so you can easily work them side by side with leds. For an easy crop with just some extraction to control environment: CMH

 

[end_of_the_tunnel]

It's a bit hard to do that unless the lower section is sealed off a bit so the air doesn't immediately mix in. I already have something like that planned out for an addition to my grow room I'm still thinking about building. Would keep DWC tubs cooler using my cool basement air. Plants grown in pots of soil/soilless like warmer temps and are often too cool tho.

For warmer air requirements some kind of damper valve setup. Similar to suggestions for tent led growers, cycle the heat from top of tent to bottom, by drawing in at top and venting from bottom. Think this could be an interesting solution for led grows in cooler months, and utilises heat from the led. Instead of having to add supplimental radiators or tubes for heat. Just a concept and would not suit all conditions.

 

[Chip Green]

Yes, yes. All this.

 

[Mikd]

I think your missing the point, having leaves warmer than ambient or colder than ambient changes transpiration drastically and will also affect the rate of metabolism. Have a look at vapour pressure deficit and see what happens if you change the leaf temps:

VPD Calculator by Everest Fernandez

This is one of the major drivers (but not the only one) of trranspiration : without water and nutes the plant simply cant keep up

Just was reading about VPD thanks for chart!

 

[Mikd]

Watch this video , around 1min15seconds in. This demonstrates the difference between how HPS radiates more heat and LED doesn't.
Its not even about how much heat, its about the difference in whats getting heated by light and how the spectrum makes that difference.
Its why LED requires a higher air temp to keep up leaf surface temp.

75f great for HPS, 85f great for LED.

I agree the environment in the cold basement needs sorting out first, but its going to cost less to heat the space to 70f and let the light do the rest than it is to heat the room to 80f.

Simplest way would be to pull the air from the house, since im pretty sure the OP's living environment isn't -30.

That is my dilemma in choosing between LED and CMH. My basement is nice a 65-67 F / RH 53% most of summer but gets cold in winter. I’m still building my room and am concerned about LST in winter if I go LED. Sorry if my terminology is off, have not grown in 35 years.

 

[Mikd]

I wonder how efficacious a U-shaped plenum around bottom of grow area would be. In cool weather drawing out, and in warmer weather blowing out via such an arrangement. Just a thought, because vent hose blowing out on one spot can be problematical.

I’m working on plans for a room at this time and trying to decide on LED vs CMH. The LEDs May be an issue for me in winter. I would ideally like to have a constant negative pressure for odor control, my wife hates the smell. I have tossed around idea of having a dedicated scrubber pulling air from ceiling and back into room at floor. I would also have a dedicated exhaust with filter to outside for overall room temp. I may be getting paranoid but would hate to have my plants metabolism slow down in winter. Appreciate the thoughtful conversation you al are having.

 

[GBAUTO]

That is my dilemma in choosing between LED and CMH. My basement is nice a 65-67 F / RH 53% most of summer but gets cold in winter. I’m still building my room and am concerned about LST in winter if I go LED. Sorry if my terminology is off, have not grown in 35 years.

I think that any benefits you would gain using leds would be offset with needing additional heating during the winter,
I think for you, CMH makes more sense.
It allows you to utilize the IR radiation it emits to heat the space during winter and your summer temps are manageable.

 

[Mikd]

I think that any benefits you would gain using leds would be offset with needing additional heating during the winter,
I think for you, CMH makes more sense.
It allows you to utilize the IR radiation it emits to heat the space during winter and your summer temps are manageable.

Thanks for your opinion.

 

[end_of_the_tunnel]

I’m working on plans for a room at this time and trying to decide on LED vs CMH. The LEDs May be an issue for me in winter. I would ideally like to have a constant negative pressure for odor control, my wife hates the smell. I have tossed around idea of having a dedicated scrubber pulling air from ceiling and back into room at floor. I would also have a dedicated exhaust with filter to outside for overall room temp. I may be getting paranoid but would hate to have my plants metabolism slow down in winter. Appreciate the thoughtful conversation you al are having.

All I can suggest is to figure out ways to trap and circulate any heat produced by the lighting. A scrubber that is recirculating the warm air rising through convection and taking it to lower levels sounds good. An exhaust fan that only vents outside when set levels are exceeded sounds like a good idea.