17 - THERMAL STORAGE IN HYDRONIC SYSTEMS

The extraordinary ability of water to store heat makes it an ideal mediator for situations where the rate of heat production is different from the rate at which heat is needed by a thermal load.  In hydronic systems, the rate and timing of heat demand can be very different from the rate of heat production. The extent of this difference, along with the operating characteristics of the heat source and balance of the system, determine if the resulting operation of the heat source is acceptable.

A common undesirable effect that results from a mismatch between heat production and heat demand is short-cycling of the heat source.  Short cycling reduces the thermal efficiency of most heat sources. It also increases emissions, increases maintenance and shortens equipment life. The most common way to avoid short cycling is to provide adequate thermal mass within the heating system.  Because of its excellent heat storage characteristics, adding water to the system is the best way to increase its thermal mass.  Thermal storage can provide several benefits when properly applied in hydronic systems, the topic of discussion in this edition of idronics™.