I forgot to mention that important part. It's not a good idea to have any propane container in your house because it can leak and turn the house into a bomb. 1 lb bottles are just as likely to leak as the big ones, just not as much to leak. Also, bear in mind that the catalyst heaters have real trouble passing the oil typically present in the big tanks when they get filled and the oil gets transferred from the station pumps into the tanks.

The bottom line is you don't want a 20 lb tank leaking propane into your house, especially with ignition sources present. It'll look like something from Burt Gummer on the Tremors movies.