Table of Contents
- Showers, wash-down, and process drains leave buildings at 25-40C - warm enough to be a valuable heat source. Wastewater (drain-water) heat recovery captures it before it disappears down the sewer.
- Drain-water heat exchangers wrap a coil around or sit inside the greywater stream, pre-warming incoming cold water. Heat pumps lift the low-grade wastewater temperature to useful levels for domestic hot water or space heating. Unlike air-to-air recovery, this is a water-to-water loop - see air-to-air vs air-to-water.
- Swimming pools, gyms, student residences, and laundries with continuous warm drain flow. Pair with the leisure-facility recovery guide for pools.
- Fouling and odor: use accessible, cleanable exchangers and a hair/trap filter. Flow matching: recovery tracks drain volume, so size to peak simultaneous use.
- In high-hot-water-demand sites, drain-water recovery often pays back in 2-3 years and cuts water-heating energy 30-50%. Validate with a payback calculation.
Showers, wash-down, and process drains leave buildings at 25-40C - warm enough to be a valuable heat source. Wastewater (drain-water) heat recovery captures it before it disappears down the sewer.
- Drain-water heat exchangers wrap a coil around or sit inside the greywater stream, pre-warming incoming cold water.
- Heat pumps lift the low-grade wastewater temperature to useful levels for domestic hot water or space heating.
- Unlike air-to-air recovery, this is a water-to-water loop - see air-to-air vs air-to-water.
Swimming pools, gyms, student residences, and laundries with continuous warm drain flow. Pair with the leisure-facility recovery guide for pools.
- Fouling and odor: use accessible, cleanable exchangers and a hair/trap filter.
- Flow matching: recovery tracks drain volume, so size to peak simultaneous use.
In high-hot-water-demand sites, drain-water recovery often pays back in 2-3 years and cuts water-heating energy 30-50%. Validate with a payback calculation.