Some may be, but here is the problem. The only moving part was the compressor (pump), but they eventually wear out, like maybe in 20 years. After 20 years, they would need to be replaced. The problem was that that heat pump was "exotic" because of those panels. A normal refrigeration mechanic had never seen anything like that heat pump. If the compressor was replaced, then the entire system may have had to have its refrigerant evacuated and replaced. I know that for many systems, the company that installed it was still around, and the tech who installed it knew how to do that. I met some of them. They already had an HVAC business, and as long as they were in business, they would maintain those systems for their customers. But some of those systems were installed 50 years ago. All of Dennis's are 40 years old and more today.
This is one of the reasons why Dennis wanted to build an industry, so that there would be widespread knowledge on how to maintain them. What often happened was that when the compressor eventually failed, nobody was around who knew how to fix them (and charge them properly with refrigerant), so even if the tech replaced the compressor and charged it, he might not have done it properly, and then the system would not work well. If if did not work well, then why use it? So, many systems were eventually removed or stopped being used.
This was one of the tragedies of wiping out all companies in the field. More than 100 companies came and went around that heat pump. Only Dennis reached the levels of sales and economies of scale to make a go of it. He was like the head of the snake. Wipe him out, and the entire industry died.
OK, time to get a little technical. As one of Dennis's installers once told me, the big difference between Dennis's heat pump and an air-to-air was that the pressures generated by those panels was twice as much as an air-to-air, which also meant higher exhaust temperatures (200 degrees Fahrenheit). It made residential air-to-airs seem like children's toys. Not only was the heat output double that of air-to-airs, but those panels made Dennis's heat pump three times as efficient (those high COPS of six and more).
Compared to industrial HVAC systems, those parameters were not too unusual, but those flat-plate evaporators made it a different ballgame. The refrigeration textbooks said that heat pumps put out 12,000 BTUs per hour per horsepower of pump (AKA compressor), but Dennis's did twice that. Dennis's idiot engineer, Brian, could not keep from reciting his 12,000 BTU mantra, even when HE produced data that showed twice that:
That was the kind of moronic stuff that Dennis often had to fight with his technical people. Dennis spent $1 million on R&D in his early days with his heat pump, as he tried to industrialize the field. One finding was that the ideal sizing for the expansion valve (where the refrigerant goes from liquid to gas, like when spray comes out of an aerosol can). I can't remember which one it was now, but the ideal was either twice or half of what was thought to be the ideal, because of the strange parameters that that panel introduced.
Also, because of the vast energy coming from the panels, it had to have an equally robust heat sink to exhaust to. It could not be air-to-air, but had to be air to water. So, Dennis's heat pump had to exhaust to water, which had a far greater thermal capacity than air did. That was one reason why commercial hot water was the ideal application: something that needed a lot of hot water. When it went on homes, it had to have a water tank, usually hundreds of gallons. So, taking long, hot showers never taxed the system. I could write a lot more, but that is enough for now.
Some may be, but here is the problem. The only moving part was the compressor (pump), but they eventually wear out, like maybe in 20 years. After 20 years, they would need to be replaced. The problem was that that heat pump was "exotic" because of those panels. A normal refrigeration mechanic had never seen anything like that heat pump. If the compressor was replaced, then the entire system may have had to have its refrigerant evacuated and replaced. I know that for many systems, the company that installed it was still around, and the tech who installed it knew how to do that. I met some of them. They already had an HVAC business, and as long as they were in business, they would maintain those systems for their customers. But some of those systems were installed 50 years ago. All of Dennis's are 40 years old and more today.
This is one of the reasons why Dennis wanted to build an industry, so that there would be widespread knowledge on how to maintain them. What often happened was that when the compressor eventually failed, nobody was around who knew how to fix them (and charge them properly with refrigerant), so even if the tech replaced the compressor and charged it, he might not have done it properly, and then the system would not work well. If if did not work well, then why use it? So, many systems were eventually removed or stopped being used.
This was one of the tragedies of wiping out all companies in the field. More than 100 companies came and went around that heat pump. Only Dennis reached the levels of sales and economies of scale to make a go of it. He was like the head of the snake. Wipe him out, and the entire industry died.
OK, time to get a little technical. As one of Dennis's installers once told me, the big difference between Dennis's heat pump and an air-to-air was that the pressures generated by those panels was twice as much as an air-to-air, which also meant higher exhaust temperatures (200 degrees Fahrenheit). It made residential air-to-airs seem like children's toys. Not only was the heat output double that of air-to-airs, but those panels made Dennis's heat pump three times as efficient (those high COPS of six and more).
Compared to industrial HVAC systems, those parameters were not too unusual, but those flat-plate evaporators made it a different ballgame. The refrigeration textbooks said that heat pumps put out 12,000 BTUs per hour per horsepower of pump (AKA compressor), but Dennis's did twice that. Dennis's idiot engineer, Brian, could not keep from reciting his 12,000 BTU mantra, even when HE produced data that showed twice that:
https://ahealedplanet.net/energy1.htm#testify
That was the kind of moronic stuff that Dennis often had to fight with his technical people. Dennis spent $1 million on R&D in his early days with his heat pump, as he tried to industrialize the field. One finding was that the ideal sizing for the expansion valve (where the refrigerant goes from liquid to gas, like when spray comes out of an aerosol can). I can't remember which one it was now, but the ideal was either twice or half of what was thought to be the ideal, because of the strange parameters that that panel introduced.
Also, because of the vast energy coming from the panels, it had to have an equally robust heat sink to exhaust to. It could not be air-to-air, but had to be air to water. So, Dennis's heat pump had to exhaust to water, which had a far greater thermal capacity than air did. That was one reason why commercial hot water was the ideal application: something that needed a lot of hot water. When it went on homes, it had to have a water tank, usually hundreds of gallons. So, taking long, hot showers never taxed the system. I could write a lot more, but that is enough for now.
Are any of Dennis’s heat pumps still in operation for the homeowners who had them installed?