Waste Heat Recovery


 Analysis > Pros and Cons
 Summary of Pros and Cons of Each Heat Recovery Method





Laundry Dryer Exhaust


Exhaust temperature and flow rate fairly consistent

Dryer lint would clog conventional heat exchangers


Dryers used continuously throughout YMCA operating hours

Significant temperature drop would cause condensation in exhaust tube

Air contains significantly less heat than water

Laundry Greywater


Wastewater contains a significant amount of energy (washers use hot water for wash and rinse, no cold water added)

To be effective, wastewater heat exchangers require a vertical drop or pool of water - laundry room in basement, slab-on-grade


Wastewater is discharged intermittently

Showers - Basement Locker Rooms


Largest source of greywater at YMCA

Locker rooms in basement, slab-on-grade. Drains pass through slab.


Regular flow

Multiple locations might require multiple exchangers

Use coincides with flow

Showers - Residences and Women's Fitness Center


Showers are on second through fourth floor -- opportunity for a vertical drop exchanger

Shower use may be asymmetric throughout day, most showers in the morning.


All wastewater passes through one drain.

Sump Tank Greywater


All wastewater passes through two sump tanks

Hot wastewater mixed with cold, reducing temperature differential and efficiency of heat exchanger


Sump tanks are adjacent to pool heaters and boilers.

Wastewater passes through concrete slab - losing some heat to the ground

Tank of water overcomes need for vertical drop in greywater

All solid and noxious waste passes through sump tanks

Continuous flow

Joshua Brandt, Sangeetha Divakar, Doug Parker, Troy Peters    Winter 2001