Hello, i'm doing my prep for my lab experiment tomorrow and have a few questions about the experiment. The schematic is attached. My lab script says the following; 2 questions. It says the precise rate of flow of water through the heat exchanger is unnecessary to know. Is this because I will be collecting all the water so will know it's mass? What is the purpose of the constant level cistern? I think this might become clearer when I actually see the apparatus but i'd sleep easier tonight knowing that I understand it's purpose. Thanks for any help you can give!