I have a 1200 sqft shop with 4 separate rooms 1 room for pouring 1 room for powder coating and ovens for baking 1 room for tying my baits and 1 room for my office. I keep them at 70 degrees in the summer and 78/80 in winter it's all on solar.
I have two older 1985/86 RCBS lead pouring pots 850 temp control I never have had any problem pouring. I had one rebuilt in 2018 and the other in 2021 both up grade temp controls but still are 850 temp.