I have had my EKO 60 with 1500 gallons of storage up and running for a few years with a complicated control system of Honeywell controllers and RIB relays with 4 temperature sensors and no data logging. I have been working for the past couple weeks installing a new Vesta controller and I am about ready to make the switch over. Still on the original control system and collecting data through the Vesta, I'm able to graph what's going on and I'm asking all who are interested to comment on what they see and what I might do to tweak the system. Let me know if you need any additional information. Thanks for your help.