I just posted over in a SOG thread about my flower room and thought I would share one of my grow rooms features on the DIY thread . I run three and sometimes four 1000watt HPS in my 8 X 12 Flower room And heat dispersal was going to be a problem and then a HPS light bulb went off in my head.... In the summertime, venting through the attic is no problem. The heat is shot into attic and blended in with the already high attic temps and vented through soffit vents and a vent gable on the roof. And since the temp in the attic gets to about 100+ there was really no problem. BUT in the winter time that heat sig would stand out like a sore thumb...My soultion... Vent the hot air into any central a/c and heating duct in your attic. This will help you keep your house warm inside and may offset your heating bill in the winter time and there is no tell-tell heat sig.
Anyway, Hope this helps someone out there.

Great Idea, butt unfortunately i dont have ducting up there already - could definately put some up there tho..
Winter Is Coming :-s

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XxNinjaxX's Super Lemon Haze - LST + Pics
XxNinjaxX's Afghan Kush X White Widow

my plants are in the attic