Considering Upgraded from CFL to HPS - A few questions

I have done 3 or 4 grows with CFL's, and while it's been a great learning curve, I can tell my grows are being limited by the light output.

I plan on building a new room 180x120x100cm (6x4x3) and using a 400w HPS (Ballast to sit outside of the grow room) for 9 medium plants. It will be a timber frame with insulation board making the walls.
It will have a intake fan, and extractor with filter, as well as circulating fan.

I have a 600w Maxi Bright ballast. Does this pump out 600w, and would blow my 400w bulb? Or is it the case that the bulb will dictate the power and draw 400w from the ballast?

It will be in one room of my bungalow (single story house), and the hot air pumped throughout my house, with selected windows open to keep temps down.

Can anyone see any problems with the design? Do you think it will raise the temp of my house enough to attract attention. I can't believe it would, but thought it best to seek advice.

Any thoughts, suggestions or and help, would be much appreciated

you need to get a 600w bulb or a 400w ballast. I'd go with the 600w bulb and find a way to increase the vertical space you have. It is best to use passive intakes when using a filter as it fucks up the negative air pressure and can allow air/smell to escape instead of being sucked through the carbon scrubber. 3 ft seems a bit short to me. can you make it any taller or are you planning on scrog or sog or lst to control height in that area? if you are i would still recommend you increase the height of the area at least a few feet. dont get me wrong, it can be done if you use a good air cooled hood and use a good fan most of the heat is sucked out right away and you can get the plants alot closer than if you dont use one. Honestly w/o the cooltube its going to be a nightmare on temps in that area.

Thanks for the help Dark D. I think that i wrote the dimensions down awkwardly. It will be 6ft tall, 4ft wide, and 3ft deep. I have a 600w bulb, but that that it would be too much for the grow room size.

I understand the rough negative pressure idea, but thought a small fan pushing in might help. I'll try passive first. I don't have a cool tube reflector, but will be extracting the heat from as close to the bulb as possible, and keeping the venting as short as possible, and in a straight line.

I dont think 600w is too much for that space at all as long as you have the proper ventilation.

I would run the 600w and get the correct fan to pump out the hot air.

Thanks for all the advice!!! I've done my size calculations and worked out the size fan necessary, then added a load to allow for carbon filter.

My other worry is having all that heat in a small room, (which is flammable) inside my house unattended for a time. What if the bulb blows?? Won't I come home to charcoal house, and much much worse, two charcoal dogs?? It's there welfare, more then getting caught, which has held me off using HPS.

Anyone got any info/advice on this? How much of a risk is it??

you got flammable equipment inside your house? like what? gas?

HTG Supply sells automatic fire extinguishers that will hang above your grow and discharge when it senses temps above 190 degrees. They will give you peace of mind and they are very reasonably priced.

fir3dragon said:

you got flammable equipment inside your house? like what? gas?

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The grow room being made of timber and insulation board would be flammable, but nothing other then your usual stuff in my house

bigv1976 said:

HTG Supply sells automatic fire extinguishers that will hang above your grow and discharge when it senses temps above 190 degrees. They will give you peace of mind and they are very reasonably priced.

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Thanks for the heads up. I'm in the UK, but sure i'll find something similar here

Hettyman said:

Thanks for the heads up. I'm in the UK, but sure i'll find something similar here

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The ones I am referring to are called "The Watch Dog" automatic fire extinguishers. Hope Ive helped.

bigv1976 said:

The ones I am referring to are called "The Watch Dog" automatic fire extinguishers. Hope Ive helped.

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You certainly have! And gangster Kermit put a smile on my face too, so... Double Win Bonus!!!!!

Hettyman said:

The grow room being made of timber and insulation board would be flammable, but nothing other then your usual stuff in my house

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i wouldnt really worry about it unless you are overloading your outlet and even then your circuit should break before then. as long as there is ventilation in your cab you should be fine.. just put a duct booster at the bottom for intake, and use the inline fan to suck the top part out. i would try to put the filter above the light so all heat goes out right away. how hot is it usually over there in the uk? i live in us, florida, and it gets pretty hot here like in the 90's summer 70-80's winter but we do got a few cold nights and i havent had any issues with a fire YET and i hope i dont lol. i got a little cab inside my closet im building and im gonna throw a 150 hps in there only cuz i never used a hps and i wanna go cheap case i mess it up i dont lose all the money, but if it works then i can sell some and get a better light

Hettyman said:

Thanks for all the advice!!! I've done my size calculations and worked out the size fan necessary, then added a load to allow for carbon filter.

My other worry is having all that heat in a small room, (which is flammable) inside my house unattended for a time. What if the bulb blows?? Won't I come home to charcoal house, and much much worse, two charcoal dogs?? It's there welfare, more then getting caught, which has held me off using HPS.

Anyone got any info/advice on this? How much of a risk is it??

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Risk is pretty much nil, I had a 400w HPS in a dodgy chipboard cab with all my clothes hanging (on the outside) and had absolutely no trouble and just wasn't at all worried, the bulbs don't emit enough heat (all be it quite a lot) to actually set fire to wood, the worst they'd do is melt the insulation if it was touching the walls :/ which I would assume it wouldn't be touching. The only real consequence of the bulb blowing is your plants will just have no light until you replace it, these things are genreally quite safe as they have to pass EU electrical tests and all that crap

btw UK Grower too XD and switching from CFL's to HPS as well soon enough putting a 250w HPS in a hx78cm wx80cm dx48cm cab.

fir3dragon said:

i wouldnt really worry about it unless you are overloading your outlet and even then your circuit should break before then. as long as there is ventilation in your cab you should be fine.. just put a duct booster at the bottom for intake, and use the inline fan to suck the top part out. i would try to put the filter above the light so all heat goes out right away. how hot is it usually over there in the uk? i live in us, florida, and it gets pretty hot here like in the 90's summer 70-80's winter but we do got a few cold nights and i havent had any issues with a fire YET and i hope i dont lol. i got a little cab inside my closet im building and im gonna throw a 150 hps in there only cuz i never used a hps and i wanna go cheap case i mess it up i dont lose all the money, but if it works then i can sell some and get a better light

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lol weather in UK is cold/rain at the best of times summers don't usually peak 30 degrees centigrade