Not sure I'd call that necessarily indicative of being true for all tanks. One tank in my lounge room made it to room temperature of 29.5C yesterday. It's away from direct light, and usual temp is 25c. The room has no air con, and I've found since starting that system that it fairly quickly moves to room temperature. In a near by room, the temps were at normal op temp for that system of 26.5. My primary system was however running the chiller for about an hour... and I reckon my whole house would fit in your driveway :p