i read ur thread from start to finish and i have to say nice grow. i read back a few pages when u were talking about the heat in the room. i do know the infer red can't go through lead. it can't read through lead and lead does'nt hold heat either. just thought i would let u people no that. so if the sheeting u were talking about has lead in it that would be why it would block the infer red would read the heat on the inside