6 ms·
Unless you're refrigerating your water, the water going down the drain will always be warmer or at the same temperature as the incoming supply. Since these thin
by adoyle 18y ago
Unless you're refrigerating your water, the water going down the drain will always be warmer or at the same temperature as the incoming supply. Since these things don't hold water, they exchange the heat as the incoming and outgoing streams move past each other, thus the effect is essentially null when you're using cold water (brushing teeth) and positive when you're using hot water (shower). When you're using water "asynchronously" (bath, toilet), there's no effect since the incoming and outgoing water move at different times.
- pmjordan 18y agoAgain, this is about efficiency, allow me to explain in more detail: The rate of heat transfer is proportional to temperature difference. If you have a predetermined amount of time for the heat to be extracted, you will get more out of a small amount of hot water than a large amount of tepid water, even if the total energy from the temperature delta to cool incoming water is equal. The predetermined amount of time is given by the hot water capacity of this device and the flow rate - i.e. how much time does a litre of waste water spend in the exchanger when the shower is in operation. Plus, there are other practical advantages to using only water coming from the shower, washing machine, etc., as it will normally not contain large particles that could clog things up, particularly when the water is stagnant or slow-flowing in the exchanger. Finally, you'd ideally feed this still relatively clean water back into the cisterns of the toilets, which don't need to run on drinking water.
- lutorm 18y agoThank you for arguing my case. :-)