Decision rule: start with the simultaneous source-and-demand map. Refrigeration waste heat becomes valuable only when its temperature, timing and hygiene boundary match a real process load.

Where the first opportunities usually sit

Useful demandTypical screening rangeFirst route to test
Raw-water or boiler-feed preheat20–50°CDirect exchange or condenser recovery
Wash water and space heating40–65°CCondenser recovery, then heat pump if needed
CIP supply and pasteurization support60–90°CHeat pump with hygienic secondary loop
Drying air or high-temperature process water80–120°CHigh-temperature heat pump after lift and equipment-envelope review
Steam dutyAbove 100°CSeparate steam-generation screen; do not assume a hot-water heat pump can serve it

These are screening bands, not design setpoints. Product, local code, cleaning validation and equipment limits determine the final boundary.

Build one hourly source-and-demand map

Record refrigeration condenser duty, compressor power and available temperature beside each useful heat demand for representative production weeks. The screen should show when both exist at the same time, not just their annual totals.

  • Separate compressor desuperheat, condensation and liquid subcooling.
  • Separate continuous base loads from batch cleaning and production peaks.
  • Keep production days, sanitation shifts, weekends and seasonal product changes visible.
  • Use storage only for short timing gaps; it does not solve a seasonal mismatch.

Treat hygiene as an architecture input

Food projects often need physical separation between refrigerant, technical-water and product-contact circuits. Record the required exchanger arrangement, leak-detection concept, water treatment, cleanability, validation temperature and responsibility for monitoring before calculating payback.

A secondary loop or double-wall exchanger can be necessary even when it reduces the apparent COP. The correct comparison is whole-system delivered heat with the required safety and hygiene barriers in place.

Compare net site energy, not recovered heat alone

  • Credit only the heat that displaces measured boiler, steam or electric-heating consumption.
  • Subtract additional refrigeration compressor power if condensing pressure rises.
  • Include heat-pump, pump, fan and storage losses at representative part load.
  • Use simultaneous annual hours and actual time-of-use tariffs.
  • Include cleaning, water treatment, shutdown work and production-access cost.

A project with a lower rated COP can still be better if it operates more hours, avoids raising refrigeration head pressure and serves a dependable base load.

Advance, measure, or pause

Advance when representative data confirms simultaneous source and demand, a credible temperature route, hygienic separation and positive net site saving. Measure first when flow, timing, baseline heat or refrigeration-power effects are uncertain. Pause when the case depends on permanently elevated head pressure, an unresolved contamination route or a heat demand that rarely overlaps production cooling.

Screen a food-processing project with your known data → · Review an anonymized meat-processing field reference →

Engineering and food-safety boundary

This guide is an early opportunity screen, not a HACCP plan, hygienic-design approval, refrigeration safety review, equipment selection or construction design. Qualified food-safety, refrigeration, pressure-equipment and process engineers must verify the site-specific boundary before procurement.