I run one in my 2' x 4' tent during lights out. It keeps temp right at 77°.
Before settling on the this heater, I tried the little oil filled heater and then a "wall mount space heater". The AC Infinity heater works perfectly with their controller. For me, it's been set it and forget it.
It's sitting the first shelf, behind the yellow extension cord and the yogurt containers.
And it runs into the tent through the port on the right side of the tent.
A steady 77° in the tent (lights out) while the garage is about 75° and the res has 28 gallons of nutrient solution at 68°.