I'm having a hard time heating my basement and want to know if i can close or seal vents upstairs to better heat the basement. Is there a way to adjust the heater itself to force more heat into the basement?
hot air rises so heat loss is inevitable, you need to prevent draughts in the basement for a start, beware you do not create condensation problems as well because there is always a trade off in anything like that.
generally you need a greater heat source output in the basement area