Which item is not a basic component of a hydronic heating system?

• A. Cooling resistors
• B. Boiler
• C. Radiator
• D. Circulator pump

Answer: (A)

Hydronic heating relies on circulating heated water to transfer warmth from a heat source to the spaces being heated. The essential pieces are a boiler to generate heat, a circulator pump to push the water through the piping, and radiators or other emitters to release that heat into rooms. The system also relies on piping, a control device (such as an aquastat or thermostat) to regulate temperature, and an expansion tank to accommodate water expansion. A cooling resistor does not fit as a basic component of this loop; it isn’t a heat source or a proper heat-transfer element in a hydronic system. The heating in a hydronic setup comes from the boiler and is moved by the pump to radiators, with heat controlled by the system’s controls—resistors aren’t part of the standard components.