upgrading from a 250CMH to a 400, question

[vindiesel]

will going from a 250CMH to a 400 increase inside tent temps at all? i use 2 137 cfm axial fans in tent roof and another venting reflector. so 3 137 cfm fans. temps now are max 77-78. in summer max was about 82. thx guys.

 

[messn'n'gommin']

I suppose that those with degree's in Physics, Electricity, etc. could argue the finer points, but, rules of thumb, as it were, is good enough for my purposes. For comparison, MH uses approximately 30% of it's wattage to produce light and the remaining 70% is given off as heat and HPS has about 35% efficiency. Although I don't know perzactly the efficiency of the CMH, I would venture to say it is somewhere in the vicinity. All that being said, yes, it will raise your temps. But I would not think greatly so. At least not to an unmanageable extent, with a small increase in airflow.

Namaste, mess

 

[vindiesel]

yeah i also have a vortex oscillating fan in tent blowing back and forth on plants. i would add another blowing right across top of plants on between plants and light.

 

[wygram]

by axial fans do you mean the computer style flat black fans?... it won't cut it... i run a 400 CMH in an air cooled hood vented by a ~140 cfm dayton blower through a scrubber and the tops can get within an inch of the glass on the outskirts of the hood with no apparent problems... wouldn't try it without a real fan... as you say your temps are in the high 70s already with only the 250... you are nearly doubling the heat output

 

[vindiesel]

damn man u estmate like my wife! lol. 400 is not doubling a 250. my wife will spend 180 at store and come home and say i only spent 100.
i hear u man thats what i'm figuring out. i have 2 137 cfm fans on top of tent and another exhausting reflector hood via duct. i may try anyway. i may only be able to use in cooler months. we'll see. whats max desired temp? like 85? i dont think i will go from 76-77 w/250 to over 84 from adding 150W. dont 4get also. CMH cooler than HPS. 2 osillating fans in tent too. 1 now but will soon be 2.

 

[greenisgold]

I grow using a 250, then go to a 400 and the 400 in my room increases temps by around 7 degrees (non aircooled hood). A 400 cmh compared to a 400 hps is about 1 -2 degrees cooler. But all room are different.

 

[Old Yeller]

I suppose you could stick a regular 150W incandescant bulb in there with your 250W cmh & see what it does to your temps before deciding if you need better heat control...

 

[vindiesel]

screw it. i'm gonna try it. all i need is a 400W ballast and a lamp. i'm sure at least i can handle it in the upcoming months. maybe not summer. i figure if i up to 400, and i'm prob going to start coco, i maight be able to pull 2z off each plant instead of just over 1. worth the try...