If you have never heard of drain water heat recovery (DWHR) until now, you are in for a treat! We love this energy-saving, water-saving, cash-saving way to get more out of every drop of hot water you use.
Let's say you turn your faucet to the hot water setting. The moment the heated water starts to come out, you use what you need and then turn the tap off again. But in that simple, brief time, much of the hot water coming out of your faucet has actually gone right down the drain unused!
The U.S. Department of Energy explains how anywhere from 80 to 90 percent of the energy draw to heat your water disappears with the unused portion of your hot water. What a waste of perfectly good (and not cheap) extra heat energy!
With a drain water heat recovery system, you can put that otherwise wasted heat energy to good secondary use—preheating cold water for future hot water needs. Keep reading to learn more about how this innovative energy and cash saving system works!
What is Drain Water?
There are three different types of water: white, grey, and black. White water is fresh tap water that has not yet been used for any purpose. Black water is, essentially, toilet water.
Grey water comes from sinks, tubs, showers, and washing machines. So this water may contain a bit of other matter, such as soap residue, hair, skin flakes, cooking oil, and washing or cleaning products.
Drain water is grey water. Essentially, grey water is "gently used" water that can still be re-purposed for a variety of energy-saving uses. For our purposes here, this water will be reused for its remaining heat content.
The way that this energy is captured for re-use will depend on what type of hot water heater system you have, so that is what we will look at next.
Re-Using Water Heat With Your Hot Water Heater
There are two basic types of hot water heaters: storage and non-storage (otherwise known as on demand).
Storage hot water heaters will use the remaining heat energy from your home's grey water to preheat the stored water for future uses.
Non-storage hot water heaters will use the remaining heat energy to preheat the water that flows out to meet immediate hot water demands.
What is important to know here is that both types of hot water heater systems can make use of this otherwise wasted heat energy.
As well, both types of systems use a heat exchange coil to capture and reuse the heat energy. The placement of this coil is just different depending on what type of system you use.
How the Heat Exchange Process Works
Different systems may have slightly different names for their heat exchange technology. Here at Gravenhurst Plumbing, we work with a wonderful company called RenewABILITY Energy. Their system is called the Power-Pipe® DWHR.
The Power-Pipe® is a patented system that harnesses grey water heat energy through a process called Falling Film Heat Exchange.
Here is a brief step-by-step of how this system works:
Unused hot water falls from the tap down the drain.
The 1 mm wide wall of fast free-falling hot water hits the sides of the drain pipe.
As it falls, this water hits a section of special copper drain pipe surrounded by coils of copper wire (this section is added to your drain pipe system during Power-Pipe® installation).
When the water enters the Power-Pipe® section of copper drain pipe, an energy hand-off occurs when the water transfers its remaining unused heat to the surrounding external copper coils.
The copper coils, in turn, are full of fresh incoming cold water, which receives the transferred heat and begins to warm up in advance of any future hot water demands.
Current estimates indicate that incoming cold water can increase by as much as 25 degrees Fahrenheit before the water even enters the water heater unit itself, which is an energy draw savings of up to 25 percent of what your hot water heater normally requires to function.
This system is what is called a Double Wall Heat Exchanger. The "double wall" is what ensures the incoming cold white water and the still-heated draining grey water never meet and mix. Rather, the combination of copper-on-copper permits safe transfer of the unused, re-usable heat energy while keeping the two water sources completely separate.
Who Can Use a Drain Water Heat Recovery System?
Here is the best news of all—the reason why we are so passionate about introducing our clients to the Power-Pipe® system of heat energy re-use: This system can be used safely, effectively, and affordably in ANY type of structure!
Single-family homes, multi-unit residences, commercial businesses, factories, and industrial warehouses are all good candidates to harness this otherwise wasted source of heat energy to save money and help conserve our planet's dwindling freshwater resources.
What Type of Savings Are We Talking About Here?
How much you save on hot water heating-related energy costs annually will depend on how much hot water you use. The Power-Pipe® system is designed to help you save up to 40 percent on your hot water heating costs annually.
The U.S. Department of Energy estimates that it will take anywhere from 2.5 to 7 years following installation to recoup your investment. Here, of course, the price of the initial installation as well as your average hot water usage both impact this estimate.
For commercial entities, installation of a drain water heat recovery system comes with additional payoffs, including smoothing the path to obtaining and maintaining LEED (Leadership in Energy and Environmental Design) sustainable building design certification.
Give Us a Call
It is simple and quick to install a drain water heat recovery system and the system itself is quite affordable given your return on investment.
Give us a call at 877-885-3403 or visit us online to schedule your initial consultation!