I thought I would share this Japanese hot water bottle I bought ,I heat it with my wood stove and it really helps with staying warm.
I saw it on "Japanology" I guess in the old days Japanese house's where pretty cold and they would use clay versions that they put in their beds .
They sell plastic ones ,and the metal ones need covers ,but like I said you can heat them up with propane or wood,
It would be good for apartment dwellers if theres a power outage .
There was one US distributor, but you can order them direct from Japan.