Does a Cooltube actually produce any meaningful heat?

Experimenting around with my Cooltube reflectors, I clearly feel that they don't heat up practically at all on the outside when used with a fan. In my judgement, this means that they would not heat up the inside of a tent at all and that I would need only a small-ish fan for the tubes and an even smaller for the smell.
In contrast, with open hoods I would need one very large, bulky, noisy exhaust fan.
Any 0.02$?

My cool tube lowers my grow tent temperature by 7F.

I run a 6" booster fan (176cfm) blowing into my 4'x2' tent and passive exhaust out of the cool tube.... 600 watt hps, canopy temps around 73F....
IMHO Cool tubes/Enclosed hoods are a MUST for controlling temps in small enclosed growing...