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