that 57 standard heater [round core] didn't come with a Ranco valve, none of the standard heaters did AFAIK, if yours had one, someone added it ... all the 57 standard [recirculating] heater had for controls was the fan switch - see accessory install manual here

Bill


Moved over to the Passing Lane

"When we tug a single thing in nature, we find it attached to the rest of the world" ~ John Muir
"When we tug a single thing on an old truck, we find it falls off" ~ me
Some TF series details & TF heater pics