I googled 'Humphrey Heaters' and it came up with images of ANTIQUE gas fired radiant Heaters'. They appeared to be inserts or surface mounted units. May not be original to the RV, or installed by a previous owner.
My concerns would be 1st, SAFETY, CO carbon monoxide and heat protection to combustibles. 2nd, parts availability. And last efficiency.
Ken
2006 Winnebago Outlook 29B E-450.
2012 Honda CR-V AWD
Blue Ox Aventa LX tow bar and Brake Buddy Vantage.