This is a picture of same heater gas valve I found on another site. From what I have read the gas valves were marked with the swastika and were from Germany but I dont really know. Thats just what I have read. The other website that shows this same heater does not mention a value
This room heater could date from before the First World War so I would seriously doubt that the swastika had anything to do with the Nazi party. I'm sure it's a lost trademark from some long defunct pipe fitting manufacturer. Value is to be determined by things we can't see from your photos. Does it work? Are the elements broken, cracked, missing? Size?, no references are given. I've seen these from being unsalable to $100.+