To collect these two graphs, additional data loggers were set up to record the temperatures going into and out of the overhead storage tanks of each building. These temperatures are the same as the temperatures at the bottom and top of the radiators. Since the bottoms of the radiators are still much warmer than the sol-air temperature, the Double Play systems are working effectively across the whole radiator. If the radiators dropped down to the sol-air temperature, then the last sections would not be giving off any heat and the system would not be working properly. The temperature differences across the radiators suggest that both systems have adequate flow, although there is not enough information to say more about the flow.