Heatsink help

G

Growinfo2323

Active Member
Hello,
I'm trying to decide on a heat sink for a cob build and was wondering what the c/w/3" rating represents?
The particular Heat sink I'm looking at say c/w/3" of 2.25
 
xX_BHMC_Xx

xX_BHMC_Xx

Well-Known Member
C/W/3 is a factor of thermal resistance. It tells you how much hotter in Celsius, relative to ambient air temps, a 3" section of heat sink will get when dissipating 1 watt of heat. A good rule of thumb for extruded heat sinks is 6sq. in. of surface area with active cooling, or 17sq. in. of surface area with passive cooling, per watt of heat dissipated. Also, check my sig for a handy calculator if you're using Heatsink USA products.
 
G

Growinfo2323

Active Member
xX_BHMC_Xx said:
C/W/3 is a factor of thermal resistance. It tells you how much hotter in Celsius, relative to ambient air temps, a 3" section of heat sink will get when dissipating 1 watt of heat. A good rule of thumb for extruded heat sinks is 6sq. in. of surface area with active cooling, or 17sq. in. of surface area with passive cooling, per watt of heat dissipated. Also, check my sig for a handy calculator if you're using Heatsink USA products.
Click to expand...
Hey BHMC just want to make sure im using your calculator correctly. Punched in numbers based off 6- 36v citizen 1212 cobs, using a Meanwell hlg-240h-36 which runs 6.7a so 1.116 per cob. 3 cobs per 4.850 heatsink from USA Heatsink. It said 11.13" on center for passive cooling. So I can run them 12" on center and be good correct?
 
xX_BHMC_Xx

xX_BHMC_Xx

Well-Known Member
Growinfo2323 said:
Hey BHMC just want to make sure im using your calculator correctly. Punched in numbers based off 6- 36v citizen 1212 cobs, using a Meanwell hlg-240h-36 which runs 6.7a so 1.116 per cob. 3 cobs per 4.850 heatsink from USA Heatsink. It said 11.13" on center for passive cooling. So I can run them 12" on center and be good correct?
Click to expand...
That's just a reference to show you how to space them on the bar if you want to run the chips linear and equidistant, which is the most thermally efficient way to runs these extrusions. You can space them however you want (within reason) as long as you have enough surface area.
 
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