533
        
            
                Heat pumps can't take the cold? Nordics debunk the myth
 
            
            (techxplore.com)
          
          
          
          
          
        This is a most excellent place for technology news and articles.
I'm not sure, likely somewhere between 5-7 years.
We wouldn't have done it if our furnace wasn't shot. As a plus our A/C leaked it's freon in the winter, so replacing it was an improvement as well.