You probably already know that your hot water heater is one of the biggest energy users in the average home. But after using all that energy to make the water hot, we only use the water for a few moments -- to take a shower or wash the dishes -- before it goes down the drain, taking all that energy with it.
Engineers have made great advances in recent years to capture that heat energy as it flows into our drains, through our pipes and down to the sewer. If you’re the “waste not, want not” type, drain water heat recovery might be a smart upgrade to your own household plumbing.
Making the Most of Waste
Drain water heat recovery works through the use of heat exchangers, similar to the one that’s stripping hot air from inside your kitchen refrigerator right now. As hot water flows away after use, the heat exchangers trap the heat energy and use it to either immediately heat more water or store it to heat water later.
Many of these systems feature their own water storage tanks that complement your hot water heater. These more robust systems allow you to trap waste heat from appliances like your washing machine and dishwasher, and they help preheat clean water to reduce your water heater’s energy load.
There are other designs that don’t store water but allow you to make use of wastewater heat when you’re simultaneously using hot water and heating cold water, such as when you’re taking a shower. With these systems, heat exchangers trap the energy directly from copper pipes leading from your shower and put it straight to work.
If drain water heat recovery systems can make a single home more energy efficient, think of what they can do for an entire neighborhood. Cities around the world are already leading the way; in Vancouver, engineers built the first major sewage heat recovery system in North America. It uses a heat pump the size of a tractor trailer to strip waste heat from sewage and use it to heat air and water in nearby homes and businesses.
This kind of large-scale installation is ideal for areas with high population density, because one major heating system can be much more efficient than thousands of small systems in individual residences. In Vancouver, this system generates 70 percent of the area’s energy needs -- all from energy that was going to waste!
If you’d like to learn more about drain water heat recovery or other ways you can enhance the efficiency of your household plumbing system, call your local plumbing experts today.