What Are Common Signs That A Diesel Genset WHRU May Have A Problem?

Common signs that a diesel genset WHRU may have a problem are less steam or hot-water output than normal, a higher exhaust outlet temperature, and poorer heat recovery overall. In normal service, these units recover engine exhaust heat to make hot water or steam, and reciprocating-engine exhaust recovery systems are typically designed around a controlled exhaust outlet temperature range rather than letting too much heat escape. If the WHRU is fouled or not transferring heat well, you usually see the useful thermal output fall while the exhaust leaves hotter than it should.

Another important warning sign is rising exhaust pressure drop/backpressure across the unit. Excessive backpressure can hurt the engine itself, not just the heat-recovery side: DieselNet notes that increased exhaust backpressure can raise fuel consumption and emissions and negatively affect engine performance. In practice, that can show up as the genset feeling "loaded up," running hotter on the exhaust side, or showing reduced performance compared with normal operation.

Operators also often watch for unstable thermal output, slower warm-up of the hot-water or steam circuit, and a growing gap between expected and actual recovered energy. Those symptoms usually point to air-side fouling, internal scaling, flow problems on the water side, or bypass/leakage issues that reduce effective heat transfer. The exact symptom depends on whether the WHRU is being used for hot water or steam, but the pattern is the same: less recovered heat, hotter exhaust leaving the unit, and higher resistance in the exhaust path.