Waste Water Heat Recovery for Showers
Waste Water Heat Recovery Systems (WWHRS): How does it work?
How does it work? Simply put: WWHRS recovers the heat energy from waste shower water, and exchanges it with the incoming Cold Water Main feed (CWM). The recovered heat energy is then used to pre-heat the incoming main by around 15-18°C. This temperature increase derived from heat energy that would normally flow down the drain, represents an energy gain, and work that the boiler of cylinder does not have to do. Therefore, a significant energy saving.
As well as feeding back to the hot water source (combi, cylinder, thermal store etc) the preheated CWM can also be routed to the cold side of the thermostatic mixer shower. This then means that to achieve the desired shower temperature (or 40 – 41°C) the shower mixer uses more free-preheated water, and less expensive hot water generated by the DHW system. Again, this generated further energy savings.