They could notice the heat if they wanted to. A few things to think about though, in most, if not all states it is no longer legal to do random thermo searches, also if they did, technically they can tell by the heat that is being exhausted from the grow room weather the activity is normal.
Also, the tractability of the thermo use by LIO has to be considered. If you live in semi industrial, or business districts then LIO would pick up thermo detection all over the place, street lamps, bakeries, pizza shops and so on, and they are not about to examine all of those possibilities to sort them out and try to pen point some poor jo that has a 1K or even 2K grow IMO.
Adieu
BlueBear Reviewed by BlueBear on . Detection how fool proof is it. If you were to keep your grow room about 3 or 4 foot from the outside walls and roof would it still give off heat that the choppers can pick up on? The place I think i could grow in is in the loft but the roof is sloping in there is about 6 foot at the highest point to about 3 foot at the lowest there is a 3x3 space easily with about 6 foot roof height. If I kept the plants down to 3 foot then i would the heat would be not be noticeable. Rating: 5