Water Heat Recovery
Water heat recovery is common in large commercial laundries and some industrial processes. The concept is similar for residential applications, but the available heat is much less. A couple of companies offer commercialized equipment for single and multi-family applications. A typical installation has a copper coil heat exchanger installed in a section of shower/tub drain. Incoming cold water flows through the heat exchanger before it goes into the water heater where it is further heated. The concept seems reasonable, but a careful analysis is required to determine whether or not a payback will result as the first cost of the equipment is not cheap. As with many energy efficiency measures, something that may not make a quick economic payback today, may save a lot more money in the future as energy prices continue to increase.
Consider how much hot water is used and where and when it drains. For example, hot water used by dish washing and clothes washing machines do not drain at the same time that cold water is being brought into the tank. Heat is only recovered if the hot water is going down the drain at the same time that cold water is being brought into the water heater. If the physical layout of the drains would require two (or more) units to be installed, the payback period is doubled if the first cost is doubled for the same potential savings.
RenewABILITY Energy Inc.
Corporate & Manufacturing Offices
60 Baffin Place, Unit 2
Waterloo, ON N2V 1Z7
Telephone: 519-885-0283, Toll free: 877-606-5559
Web site www.renewability.com
Source: Text by Bob Fegan; product information and images from the manufacturer’s web sites linked above; 5/2008;