Audits typically find 5–15% of fuel recoverable with sub-3-year paybacks; the technical potential is larger (US DOE: 20–50% of input energy is rejected as heat across temperature bands).
From our guide: Waste Heat Recovery — full context, charts and sources there.
Boilers, kilns, heat exchangers, valves and steam lines lose energy continuously. Inzonex makes patented (UK GB2508992.1) removable modular insulation — snap-fastened covers engineered per temperature tier, not generic off-the-shelf jackets: