Hello erky,

When sizing an A/C for a grow room or grow area; a good rule of thumb is to treat the heat from a HID bulb (MH or HPS) as an electric heater.

1/KW per hr is equal to 3,414 BTUs. So 8 lights at 600w each is equal to 4,800watts or 4.8 kw. That gives you 16,387 BTUs to deal with, so a 24,000BTU a/c would be a nice size for your room. It should have enough capacity to cycle on/off and not have to run continuous.

Hope this helps, and good luck growing. :thumbsup:
oldmac Reviewed by oldmac on . will a 24000 btu air-con unit do the tick? i have 8 x 600w in a 10 x 14 foot room, with a 315mm and 250mm fan sucking out and a 250mm pumping fresh air in,the balast are outside the room, its cold outside now its the end of september and the room is still getting hot 29-33, can any1 please tell me what size a/c i will need, any advice will be great. thanks ps easy to fit one as i will try and fit it myself. Rating: 5