One disadvantage that Bluehart lists of classic heat pumps is the need for a refrigerant fluid. But Bluehar uses helium internally; I wonder how often the helium would need to be replaced.
I thought that helium was in short supply. Would that make these things expensive? Also, I know they said it's quiet, but if the thing operates on a 60hz cycle, wouldn't that create a pervasive hum?
The company cited in the article is [Bluehart](https://blueheartenergy.com/our-technology)
One disadvantage that Bluehart lists of classic heat pumps is the need for a refrigerant fluid. But Bluehar uses helium internally; I wonder how often the helium would need to be replaced.