thewinghunter
Active Member
thanks as always!
Uncle Ben's Gardening Tweeks and Pointers
- Thread starter Uncle Ben
- Start date
I have two 747 cfm fans. One of them pulls air over 4 1000 watt lights the other sucks air from the room through a filter into my veg room.
I started thinking that instead of running the ducted fans over the lights if I should just move more room air. Shouldn't it all equal out in the end? I'm thinking that moving the lights in the hoods is a bottle neck for the fans and doesn't stop the radiant heat.
Anyone ever measured temps to see how effecting ducted lights actually are?
I started thinking that instead of running the ducted fans over the lights if I should just move more room air. Shouldn't it all equal out in the end? I'm thinking that moving the lights in the hoods is a bottle neck for the fans and doesn't stop the radiant heat.
Anyone ever measured temps to see how effecting ducted lights actually are?
DaveCoulier
Well-Known Member
Ive tried it both ways, and Ill be sticking with my air cooled hoods & ducting. Makes quite a difference. It'd be impossible for me to go without them in my setup.
Dave,
I am reading on of your other threads about yield. There is an article that says air cooling removes heat at the source. Air cooling removes the hot air in the hood, but does nothing to stop the radiant heat. On a cold day the sun still feels hot on your skin. I'm wondering if everyone is forgetting about this radiant heat.
I am reading on of your other threads about yield. There is an article that says air cooling removes heat at the source. Air cooling removes the hot air in the hood, but does nothing to stop the radiant heat. On a cold day the sun still feels hot on your skin. I'm wondering if everyone is forgetting about this radiant heat.
DaveCoulier
Well-Known Member
Im no expert on heat, but I understand what you mean. Reflector heat shields should help reduce some of that radiant heat. There should be some youtube clips regarding these products.
I'm not trying to argue with you, first of all...
If you reduce radiant heat you will also reduce the light. I'm simply thinking there is nothing that can be done. The heat is just part of the spectrum of HID lights. We can't blow it away anymore than we can blow away red light.
I'd be curious to set up a grow tent to actually measure this stuff, just don't have the space right now. Since I don't use CO2 I was thinking it may make more sense to simply move a lot of air in the whole room with the fan that would other wise pull on my lights. I currently do move air in the room and in my lights but have the idea that it may be better to use all my fans to simply move room air.
I'm also wondering how people handle AC when moving a lot of room air, seems like it would defeat the AC. I currently run my AC and pull 747 cfm through a can filter out of the room. I send this to my veg room so the AC isn't fully wasted, but it does blow out of the veg room.
Just trying to understand my environment and not get stuck in the standard way of thinking.
If you reduce radiant heat you will also reduce the light. I'm simply thinking there is nothing that can be done. The heat is just part of the spectrum of HID lights. We can't blow it away anymore than we can blow away red light.
I'd be curious to set up a grow tent to actually measure this stuff, just don't have the space right now. Since I don't use CO2 I was thinking it may make more sense to simply move a lot of air in the whole room with the fan that would other wise pull on my lights. I currently do move air in the room and in my lights but have the idea that it may be better to use all my fans to simply move room air.
I'm also wondering how people handle AC when moving a lot of room air, seems like it would defeat the AC. I currently run my AC and pull 747 cfm through a can filter out of the room. I send this to my veg room so the AC isn't fully wasted, but it does blow out of the veg room.
Just trying to understand my environment and not get stuck in the standard way of thinking.
DaveCoulier
Well-Known Member
I decided to look up thermal radiation and came across this wiki page. Of course wiki isn't always the most accurate source, but if Im reading it right, we only see the radiant heat when its really really hot, and most of the time the radiant heat/radiation is in the infrared range, which our plants really dont care much for, so we lose nothing if a reflector heat shield can reduce it.
http://en.wikipedia.org/wiki/Thermal_radiation
Hotwired
Well-Known Member
You are pulling air thru four 1000 watt lights in a straight line. I could care less how fast the air is moving thru the line, you will still have heat problems at the end. You will gain 20 degrees of heat thru that line alone no matter how big your fan is.
The tent idea is in the right direction but you don't need that. If you can suck much cooler air thru that line from another area then do it. But the idea about "moving all the air around" wont work. That is what they do in sealed rooms and I don't think your room is sealed.
My idea to you is to split the lights in 2 rows if you can. Use a splitter right at the fan and suck thru 2 lights each at once. This will help reduce heat immediately. Maybe by as much as 10 degrees.
The main problem you face seems to be where you are getting your air for the hoods. If you are sucking it right out of the room the plants are in then I can't help you. If you can get the intake air from a cooler room (72 degrees and less) this will solve all your problems. You can use one inline fan for the 4 lights (split them if you can in 2 rows) and another small inline fan sucking from that same cool room and pushing thru a carbon filter.
Or you can say fuck all that and hang the lights vertically with no hoods and get at least a 20k btu A/C
The tent idea is in the right direction but you don't need that. If you can suck much cooler air thru that line from another area then do it. But the idea about "moving all the air around" wont work. That is what they do in sealed rooms and I don't think your room is sealed.
My idea to you is to split the lights in 2 rows if you can. Use a splitter right at the fan and suck thru 2 lights each at once. This will help reduce heat immediately. Maybe by as much as 10 degrees.
The main problem you face seems to be where you are getting your air for the hoods. If you are sucking it right out of the room the plants are in then I can't help you. If you can get the intake air from a cooler room (72 degrees and less) this will solve all your problems. You can use one inline fan for the 4 lights (split them if you can in 2 rows) and another small inline fan sucking from that same cool room and pushing thru a carbon filter.
Or you can say fuck all that and hang the lights vertically with no hoods and get at least a 20k btu A/C
riddleme
Well-Known Member
I am currently researching Infrared heat and planning on adding it to my next grow (experimentally) to try and truely recreate the suns rays more exactly
hotwired,
people with sealed rooms commonly run ducted lights... they just pull from outside and vent outside. I actually do the same. I do what you say. I pull from outside split into two, run each line over two lights reconnect the two to one and pull 747 cfm. I pull from outside and vent in my attic. When I feel the air comming off the lights it is cold... About the same as outside air, that is why I am doubting the effectiveness of this. If I can measure the outside air, then measure then output of the lights, I could get a better idea. I think I will do this. The bottom line for me is the air doesn't stop radiant heat.
Dave, I don't think it needs to be 'really hot' to get radiant heat. The hotter the lights the more radiant heat. Also, my lights are 'really hot'. What do you mean by really hot? 100's? 1000's? 10,000s? This term is really ambiguous.
people with sealed rooms commonly run ducted lights... they just pull from outside and vent outside. I actually do the same. I do what you say. I pull from outside split into two, run each line over two lights reconnect the two to one and pull 747 cfm. I pull from outside and vent in my attic. When I feel the air comming off the lights it is cold... About the same as outside air, that is why I am doubting the effectiveness of this. If I can measure the outside air, then measure then output of the lights, I could get a better idea. I think I will do this. The bottom line for me is the air doesn't stop radiant heat.
Dave, I don't think it needs to be 'really hot' to get radiant heat. The hotter the lights the more radiant heat. Also, my lights are 'really hot'. What do you mean by really hot? 100's? 1000's? 10,000s? This term is really ambiguous.
Hotwired
Well-Known Member
The air stops most of the heat depending on the temp of the intake. I would also like to see the results of your temperature test. Should be interesting.
The radiant heat needs to be replaced by your exhaust fan. Do you also use the same cool outside air to cool the grow room? I have half the setup as you and I still need a portable A/C to cool the room.
The radiant heat needs to be replaced by your exhaust fan. Do you also use the same cool outside air to cool the grow room? I have half the setup as you and I still need a portable A/C to cool the room.
hotwired,
I use a wall mounted AC. I can't remember the BTU. I lost the manual and can't see the model number... The room is kept at 78 F.
What do you mean the radiant heat needs to be replaced by the exhaust fan ? The exhaust fan on the ducts? That doesn't move radiant heat. Cooling the room with the AC and changing room air remove air heat that gets generated when the radiant heat hits things (plants, walls, etc)
I use a wall mounted AC. I can't remember the BTU. I lost the manual and can't see the model number... The room is kept at 78 F.
What do you mean the radiant heat needs to be replaced by the exhaust fan ? The exhaust fan on the ducts? That doesn't move radiant heat. Cooling the room with the AC and changing room air remove air heat that gets generated when the radiant heat hits things (plants, walls, etc)
Has anyone considered hanging their lights at an angle? For example, say I have a 4x8 and two 1000 watt lights. The hood has a sharp shadow. I was thinking of hanging the lights at the ends of the table and angle them so the light that normally bounces off mylar will be angled down and the other side will beam to the other side of the table. The light goes off in a circular way so it seems like all the light could be hitting plants. The middle of the table would get less light (farther away) from any one light but it would be doubled. I just don't want my plants all bending, but I rotate them often.
Hotwired
Well-Known Member
Don't you have a fan that pulls out all your hot/old air from the room itself? I have an exhaust fan that pulls out all the old/hot air (caused by radiant heat from my hoods) and is replaced by cool air from outside the room.
We are doing the same things but I don't think you are understanding me. No problem. I'll go on my way.
Did I say something to offend you? Why go on your way? Why don't we understand each other. I got confused when you said radiant heat needs to be replaced by my exhaust fan. I didn't follow, now I see you are saying the hot air needs to be replaced. I see that you mean you vent the lights and the room. I do the same. I pull out of the room to my veg room. It is actually cool air because I have an AC. I do this to pull in drier air from anywhere it can get it. I have an input vent and it also leaks in through any openings. This is by design, the room has negative pressure so smell doesn't leak. I appreciate discussing this, but if you don't want to continue that is OK, too.
My big question is about using a ducted light in a non sealed room. I understand why one would run a ducted light in a sealed room, but if the room isn't sealed just move all the air out as much as you can. I mean I may be able to remove more heat and also humidity if I take the light fan and use it to pull more room air out. The radiant heat is the same each way. The diff is that the fixture will heat up more if I don't run the duct fans. But this fixture heat can be cooled by changing the room air. I don't know if I am being clear. This makes sense to me, but I don't feel I am doing a good job of expressing this idea.
My big question is about using a ducted light in a non sealed room. I understand why one would run a ducted light in a sealed room, but if the room isn't sealed just move all the air out as much as you can. I mean I may be able to remove more heat and also humidity if I take the light fan and use it to pull more room air out. The radiant heat is the same each way. The diff is that the fixture will heat up more if I don't run the duct fans. But this fixture heat can be cooled by changing the room air. I don't know if I am being clear. This makes sense to me, but I don't feel I am doing a good job of expressing this idea.
Hotwired
Well-Known Member
I understand completely.
Lights will be a bitch either way. If we didn't want to try to "cool" our lights with forced air we might as well go vertical and go all out A/C.
But I believe you can still cool off your room (almost) with just a single fan ducting the lights. Even to the point of getting almost all the radiant heat. It all depends on the ambient temp of the air you use. I know this because I've done a few experiments using a tent in a room. I was able to control the temp of the intake air for both the lights and passive intake for the tent. I was also able to turn off one fan or the other in order to see what variables would happen in case one shut off and the other fan stayed on.
The experiment used two 1000 watt lights in a 5 x 10 tent. The experiment was done during a cool month with outside temps in the 50's and room temps in the low 60's. One light was turned on at a time and both fans were turned on. The fan for the lights (250 cfm only) sucked in air from outside the tent, thru 6" duct and outside. Room temp was 62 degrees. The fan for the inside of the tent (175 cfm) sat on top of a carbon filter and sucked air from outside of the tent, into the tent, and out thru the filter. Basically this was done to create a passive intake and negative pressure inside the tent. This experiment also proved the effect of airflow speed. No way near as much cfm is needed to cool your lights as you might think.
The temp inside the tent was 65 degrees with no lights on. With one light on the temp inside the tent went up only 2 degrees to 67. When both lights were on the temp reached 70 degrees. Remember this was with a 250 cfm TD-150. Of course the radiant heat was still getting sucked out by the other fan so we shut it off completely. We let the fan stay off for 1 hour and came back to check temps.
Temps were only 75 degrees. Somehow heat was escaping and after doing a good search we saw that the hoods, even tho they had the insulation under the glass, were still sucking air out. But it was pretty much insignificant to letting heat escape.
We brought in an A/C with heat and played with ambient temps for every 5 degrees until we reached a point of the tent getting too hot. The temp was 72 degrees ambient temps outside of the tent. We found that once the temps got over 72 we had heat problems of 84/86. There was no way at these temps that the inside tent fan could be turned off without temps reaching 90.
I feel that this experiment will work the same in a room without a tent. As long as you are sucking ambient temps of 72 and lower you can keep temps down. But you would need both fans on to take the heat out. If the temps are very low, 65 and below, I think you can get away with one fan but it might have to be a bit stronger than 250 cfm.
Lights will be a bitch either way. If we didn't want to try to "cool" our lights with forced air we might as well go vertical and go all out A/C.
But I believe you can still cool off your room (almost) with just a single fan ducting the lights. Even to the point of getting almost all the radiant heat. It all depends on the ambient temp of the air you use. I know this because I've done a few experiments using a tent in a room. I was able to control the temp of the intake air for both the lights and passive intake for the tent. I was also able to turn off one fan or the other in order to see what variables would happen in case one shut off and the other fan stayed on.
The experiment used two 1000 watt lights in a 5 x 10 tent. The experiment was done during a cool month with outside temps in the 50's and room temps in the low 60's. One light was turned on at a time and both fans were turned on. The fan for the lights (250 cfm only) sucked in air from outside the tent, thru 6" duct and outside. Room temp was 62 degrees. The fan for the inside of the tent (175 cfm) sat on top of a carbon filter and sucked air from outside of the tent, into the tent, and out thru the filter. Basically this was done to create a passive intake and negative pressure inside the tent. This experiment also proved the effect of airflow speed. No way near as much cfm is needed to cool your lights as you might think.
The temp inside the tent was 65 degrees with no lights on. With one light on the temp inside the tent went up only 2 degrees to 67. When both lights were on the temp reached 70 degrees. Remember this was with a 250 cfm TD-150. Of course the radiant heat was still getting sucked out by the other fan so we shut it off completely. We let the fan stay off for 1 hour and came back to check temps.
Temps were only 75 degrees. Somehow heat was escaping and after doing a good search we saw that the hoods, even tho they had the insulation under the glass, were still sucking air out. But it was pretty much insignificant to letting heat escape.
We brought in an A/C with heat and played with ambient temps for every 5 degrees until we reached a point of the tent getting too hot. The temp was 72 degrees ambient temps outside of the tent. We found that once the temps got over 72 we had heat problems of 84/86. There was no way at these temps that the inside tent fan could be turned off without temps reaching 90.
I feel that this experiment will work the same in a room without a tent. As long as you are sucking ambient temps of 72 and lower you can keep temps down. But you would need both fans on to take the heat out. If the temps are very low, 65 and below, I think you can get away with one fan but it might have to be a bit stronger than 250 cfm.
DaveCoulier
Well-Known Member
You misread my post. I said you only see the radiant heat when the item is really hot. Like a fireplace poker thats been allowed to sit in the fire for awhile. If you pull it out the iron will be glowing red. At that point we are able to see the radiant heat being emitted.
DobermanGuy
Well-Known Member
im pulling from the outside, cooling 1 1000w, with a 400cfm. My a/c w/ thermostat keeps it within 2 degrees or so of its thermostat setting. Talk about some radiant heat coming off the glass, with the fan on high, using most of its capacity; i can imagine damage if the flowers get within 6-8"
I dont think ill ever use a light thats not air-cooled, unless i come across an indoor greenhouse (which isnt going to happen anythime soon).
I dont think ill ever use a light thats not air-cooled, unless i come across an indoor greenhouse (which isnt going to happen anythime soon).
hotwired,
I guess we would have to know how much radiant heat the glass and fixture absorb to know how much heat is being removed.
with vert you can still opt for cool tubes...
I am basically ducting because I am assuming it is optimal based on the fact that many people do it. I have seen photos of large scale indoor hydro farms that use no ducted lights. The keep them up higher but they have so many lights they overlap and get great coverage. I know things are different in a bedroom.
dave,
isn't radiant heat IR (invisible) you see light in the visible range (after all you are seeing it)
I'm not sure this is right thought, because a laser that is %100 green can will be able to be hot
I'd like to discuss this with some of my physics friends.
I guess we would have to know how much radiant heat the glass and fixture absorb to know how much heat is being removed.
with vert you can still opt for cool tubes...
I am basically ducting because I am assuming it is optimal based on the fact that many people do it. I have seen photos of large scale indoor hydro farms that use no ducted lights. The keep them up higher but they have so many lights they overlap and get great coverage. I know things are different in a bedroom.
dave,
isn't radiant heat IR (invisible) you see light in the visible range (after all you are seeing it)
I'm not sure this is right thought, because a laser that is %100 green can will be able to be hot
I'd like to discuss this with some of my physics friends.