John Cantor has been working with heat pumps since the late 70s and with refrigeration much earlier. He wrote his book along with Gavin DJ Harper (one of the BetaTalk guest battery experts) back in 2010 just before the renewable heat incentive came into play. He is joined by regular guests Ken and Steve who are big fans of John's pioneering work. It's a longer than usual episode so please use the chapter markers if you wish to find specific topics being discussed.
John's book is here https://www.amazon.co.uk/Heat-Pumps-Home-John-Cantor/dp/1785007793/ref=sr_1_1?dchild=1&keywords=heat+pumps&qid=1626527840&sr=8-1