hydronic

Hydronic refers to systems that use water or other liquids as the heat-transfer medium for heating and cooling buildings. The term is common in plumbing and HVAC to distinguish liquid-based heat distribution from air-based methods.

In a hydronic heating system, a heat source such as a boiler or heat pump warms the circulating liquid, which then transfers heat to occupied spaces through radiators, baseboard units, or radiant floor assemblies. In cooling applications, chilled water is circulated through coils in air handlers or through radiant cooling surfaces to absorb heat from spaces and release it elsewhere. All hydronic systems rely on pumps, piping, heat exchangers, and an expansion or pressure-control component to manage volume changes as the liquid heats and cools.

Fluids used are typically water, often with additives such as glycol to prevent freezing or corrosion. Temperature ranges vary by use: heating systems may circulate water at 120–180°F (49–82°C) for comfortable radiant and conventional radiators, while chilled-water systems operate around 40–50°F (4–10°C).

Advantages of hydronic systems include quiet operation, even heat distribution, potential for zoning and precise temperature control, and compatibility with renewable energy sources. Drawbacks include higher upfront cost, space requirements for equipment and piping, and the need for regular maintenance to prevent leaks, corrosion, or scaling.

Maintenance focuses on leak detection, corrosion control, flow balancing, and ensuring pressure and expansion components function correctly. Hydronic systems are used in residential, commercial, and industrial settings and can be integrated with solar, heat-pump, or thermal storage technologies.