its UL listed so it should be safe.
with that said - i have a rule in my house for winter; everyone has to wear socks, slippers, sweaters and pants. if you are still cold then, then i will turn up the head. I am able to keep the heat at 20 celcius in the winter without moans and groans from the wife and kids. Though my mother in law likes to show up in a t-shirt and skinny jeans and tennis socks and i have to crank it to 25
My basement stays the warmest though due to location of the furnace.
try keeping the furnace fan on all year round to keep the temps equalized through the house.