Technical Insights

Fenwick HVAC Blog

Practical information on heating, cooling, refrigeration, and controls—grounded in service experience and sound system design.

Heating System Design · October 19, 2026

Hydronic Aux Heat vs Dual-Fuel System

A practical explanation of conventional dual-fuel changeover versus a hydronic auxiliary heating coil that lets the heat pump keep operating. Includes three clearly labeled engineering illustrations.

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Illustrative graph comparing heat pump capacity and building heating load at varying outdoor temperatures