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How much heat does a 250 watt and 400 watt HPS bulb emit?

Discussion in 'Grow Room Design & Setup' started by Crypnotic, Aug 3, 2010.


    Crypnotic Active Member

    I want to upgrade my grow room with 400 watt or 250 watt HPS light. Heat is a big concern for me. I live in FL the temps are very high. My grow room is a 6x2x10 space, but i will only grow in 2 or 3 feet of it, but I have the entire space to use for the dispersion of heat. I'm looking for quantified answers or applied practical knowledge (i.e. "I used a 250 watt in my 2x2x8 room and it raised the temp by 15 degrees w/out ventaliation). I have the following questions:

    1. How much heat does a 250 watt bulb emit? (how many degress does it raise the room. How much heat does it emitt per sq. ft.?)
    2. How much heat does an average reflector add to the heat of a 250 watt bulb?
    3. How much heat does a 4000 watt bulb emit?
    4. How much heat does an average reflector add to the heat of a 400 watt bulb?

    Once again, I'm looking for quantified/applied answers. Everyone should know the demensions of their grow space. Everyone should know the temp of the room w/ and w/out the lights on. Please let me know what size space you grow in and how much the temp it raised w/ out venting the air

    Thanks guys.

    Crypnotic Active Member

    I was doing some reading and I saw a post of grow room 2x3x72 and his 400 hps raised his temp by 30 degrees. Anyone want to share their experiences?

    Scott187 Active Member

    i dont know about a lower bulb, but my 400 watt is about 73 at night and around 88 being very high at night, with just 1 fan

    skidwaykush Member

    i dont have exact figures but i use a 600 watt mh and it feels as if im on the roof of a house sun tanning. i recomend a air conditioner or really good ventilation or a simple combination of the two my area is 4x4x8 used for only 1 plant and lots of branchs or hydro totes with 6 plants in each this is a older version now upgraded many times hope this helps at all i know my light raises temps sometimes in 18 to 25 above the light with no cooling or ventilation room i recomend couple of feet for fan etc. outside temp and humidity have alot to do with it hope this helps and good luck Apr25_0003.jpg

    skidwaykush Member

    my bulb also helps heat in winter, the air, water, and soil

    meezy4tw Active Member

    I have a 250w hps in my closet. My space is 4wide-2feet deep-6feet tall. I only use oscillating fans for air due to having a double sliding door for the closet, I use one 16 inch fan and two 10 inch fans. Without the light on my area is about 68-73. If I have the light on with no fans, room temp gets about 90-95. With the fans it stays at around 77-83 degrees. I actually think this is still too warm for plants so I'm currently planning on getting some better ventialtion.

    If you plan on doing a personal grow in a space of 3x3 a 250 watt should be fine, but a 400 will work too.

    Crypnotic Active Member

    Thanks guys. My grow room already stays at an average of 84 degrees w/ on 10' fan with my cfls. So it looks like I can expect anywhere from 15 to 30 temp raise w/ a 400 hps. Wonder if running light w/ out a reflector would lower the temp any? I'm sure it does but not sure by how much.

    Rusko Active Member

    cool tube but careful with ducting,fires.

    skidwaykush Member

    im on the same page as meezy on this one they have lots of nice inline fans and lots of things to choose i always go with my best judgement and always be fire safe i ve had a house fire before and it wasnt pretty it wasnt related to growing but easily could have been.

    purplehazin Well-Known Member

    I'll just give you an example of how my setup is temp wise.

    I have a 400W HPS with a homemade cooltube. A 400CFM fan sucks through it. Lets say the ambient room temp is 78F before I turn the light on. If I were to have that running with no other fans blowing over the plants then the temp on the canopy would go up to about 95F. Once you add an oscillating fan to blow over the canopy, that drops down to 90F, then factor in some AC, and my 2x3x5 cab stays about 83-87F with the light on.

    Rusko Active Member

    im about to use a 400w in a room like that size,i was worried about heat but i should b good..gettin some good ideas

    Rusko Active Member

    sounds legit purplehazin.my 400w is coming in today! cant wait to set it up.i was worried for awhile about heat and fires....BUT ive heard alot of people talkin about ther 400w setup and how they dont have real good exhaust or intake and all is well....im goin to have multiple fans..some ducting and a inline duct fan 500cfm for exhaust
    home made cool tube sweet.i orderd a batwing soo a cool tube would b nice for my closet setup.ANY TIPS?

    Crypnotic Active Member

    Very cool. thanks guys for the input it really helps.

    BTK3ill Well-Known Member

    how much more heat does a 400 give off compared to a 250 anyone know?

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