My beer is fermenting in my unfinished basement (insulated) because it has lots of room and it is pitch black, but the temperature is around 17c. I put the fermenting gallon 1 inch from my water heater and it gets around 18c so far, but I do not want to leave the gallon there because it is not conveniently placed.
I could ferment in a closet at the main level, but again the temperature is 16c during day and 18c at night.
What is my best option here, should I build some kind of temperature controlled closet? What is your setup?