Heat Difference - 400w Hps Vs 315 Cmh

[dirkdaddy]

Does anyone have a guess as to how a 315 cmh light stacks up against a 400 w hps light in the heat department?

Let's say I am not concerned about the greater yield per watt that cmh delivers, nor am I concerned about PAR, lumens, etc, I simply want a comparison on heat. The comparison of heat between a 315 cmh and 600w hps and 1000w hps is pretty clear, but the comparison of a 315 cmh to the heat of a 400w hps is not.

In a 3x3 tent running a 400hps aircooled hood with a 4" vortex running full out I can keep the temp at about 3.5 degrees above ambient temp in the room.

Will I see an improvement on that by switching the light and ballast out with a 315 cmh?

 

[PassTheJ]

I don't know how you guys do it with HPS. I run four 1200 watt LED in a 4x8 with 1900 real watts out the wall and my temp sky rockets 20 degrees above ambient. That's with TWO 10" inline fans at 740 cfm each on full blast and four 12" clip fans. If you stick your head at the end of my vent, youd think you're on a motorcycle going 60..

 

[DGP]

Does anyone have a guess as to how a 315 cmh light stacks up against a 400 w hps light in the heat department?

Let's say I am not concerned about the greater yield per watt that cmh delivers, nor am I concerned about PAR, lumens, etc, I simply want a comparison on heat. The comparison of heat between a 315 cmh and 600w hps and 1000w hps is pretty clear, but the comparison of a 315 cmh to the heat of a 400w hps is not.

In a 3x3 tent running a 400hps aircooled hood with a 4" vortex running full out I can keep the temp at about 3.5 degrees above ambient temp in the room.

Will I see an improvement on that by switching the light and ballast out with a 315 cmh?

If the HPS light has glass and ducted cooling air coming in via a fan with a duct going out of the tent then it will be cooler than CMH. If the CMH has cooling ducts it would be similar and about as cool. However, the CMH lamps I have seen don't have a cooling duct system so they would probably heat up your tent quite a bit more than a air cooled HPS.

I did thermal studies of various light sources before switching to all LED COB's and Quantum boards and the thermal performance of any given light that lacks isolated cooling ducts is about the same (a watt is a watt, T5, HPS whatever). With LED's I put the drivers outside the room and so very little heat is added. Also, minor point is that with HPS you can put the ballast outside the room as well saving the additional heat it produces.

CMH has that beautiful color correct white light (CRI= 80 or better). The only other way to get that quality of light or better (CRI= 90 or 95) is to go with quality COBs or Quantum boards. HPS is about CRI=39 (CRI=100 is the best you could theoretically achieve). The reason Gavitas and the like are so good is the light quality (color rendition index).

Dee

 

[dirkdaddy]

My idea in this scenario was to keep the air cooled hood the same and simply swap out the current ballast for a cmh one and use a socket adapter for the bulb. Was just curious if this set up would run any cooler than a 400w hps.

My eventual switch to CMH growing is essentially assured based on what I know now and what I've learned reading this forum. The equipment I'm using right now was purchased a few years ago before cmh and LED became more popular, and has been sitting in storage, hence I'm just "using what I got" at this point.

For me it's just a question of whether I should drop the dollars on a new CMH ballast and bulb right now before summer to keep temps down even lower than my 400w hps can get, or just ride out the summer period with the hps and upgrade later on this year.

 

[sixstring]

My idea in this scenario was to keep the air cooled hood the same and simply swap out the current ballast for a cmh one and use a socket adapter for the bulb. Was just curious if this set up would run any cooler than a 400w hps.

My eventual switch to CMH growing is essentially assured based on what I know now and what I've learned reading this forum. The equipment I'm using right now was purchased a few years ago before cmh and LED became more popular, and has been sitting in storage, hence I'm just "using what I got" at this point.

For me it's just a question of whether I should drop the dollars on a new CMH ballast and bulb right now before summer to keep temps down even lower than my 400w hps can get, or just ride out the summer period with the hps and upgrade later on this year.

yes if you do the swap like you are talking about it will be cooler

 

[dirkdaddy]

Made the conversion in one of my tents. The CMH certainly bests the 400w hps in heat. My temps are currently running either exactly the same as ambient room temp with the CMH versus 2 to 3 degrees over with the hps. A few times it has read under ambient room temp due to the tent being on the floor and the room thermometer is higher up on a counter.

I'm impressed. Will be switching my other hps ballast to CMH very soon.

Going with 4200k Phillips bulbs for flowering instead of using a 430w hortilux. Maybe in the winter I'll do a side by side comparison.