it might not surprise you that i spend a decent amount of time researching ways to reduce the household energy use and increase efficiency. while doing research on grey water collection i was reading about a device that collects the heat from greywater and radiates it to the house as it drains into the collection tank via a heat exchanger.
this seemed like a pretty complex device to collect what didn’t seem like that much heat. i don’t use much hot water for washing dishes or taking a bath, and most of our clothes washing is done in cold water.
it did get my gears turning.
what if you could do something that required no work and could save this heat? that would be worth it right? it occurred to me that if you just left your hot bath water to sit until the water in tub was cold, it would have already achieved the task of extracting all the heat out of it before it went down the drain, making the need for a greywater heat extractor unnecessary.
so thats what i do now, leave the water in the tub until it has become cold. how much this saves in energy savings, i have no idea, but if any one technically minded wants to calculate this, i would be very interested to find out.