Quote Originally Posted by Pete Hutson View Post
Cascade second stage is the only reliable way to reach these temperatures. R410A over R134A seems to be the answer.
This is one method, but you do not need to cascade R410a, I have system prototypes running, on DHW (double barrier heat exchangers) that produce water well over 80C. I am able to store 50% more energy in a cylinder (if required, but normally not) than present systems available in NZ, the system is able to work in bigger ambient ranges, and has greater COPs than any system presently on the market. All this makes the unit much more reliable, than any system on the market.
The SFT principle (which is Patented) has been tested R410a, R22, R134a, R407C, it will work on any sub critical refrigerant. In each case with a general reducion in power of 30% for the same amount of stored energy produced. They are mechanical principles, not electrical savings (which would further improve COP, ie DC motors)