There are many potential uses of heat recovery systems, both domestic and commercial/industrial. These include, among others:
- heating of spaces
- ventilation of spaces
- heating of water
- pre-heating air and water to reduce the energy demand of boilers
- industrial scale drying (for use in manufacturing processes, etc.)
This is by no means an exhaustive list; depending on the specifications of your existing heating system and heating needs there may be other opportunities for heat recovery.