Electrically Heated Systems

Compact electric boilers, water heaters, or combination water heaters are also available for use in hydronic systems. These boilers are characterized not only by their compactness but also by their quiet operating characteristics.

The extreme compactness of an electric hydronic boiler is illus­trated in Figure 7-36. The heat exchanger, expansion tank, and operating controls are all mounted on the wall in a relatively small space.

Electrically Heated Systems

Figure 7-35 Typical installation of a humidifier in a hydronic heating system.

A central heating unit (e. g., an electric-fired boiler) can be elimi­nated in some systems by using thermostatically controlled electric heating components in the baseboard units. Figure 7-37 illustrates a system of this type. Note that there is no boiler. The water is cir­culated through the system by a pump, and a uniform temperature can be maintained by the heating element in each baseboard.

The heating system illustrated in Figure 7-37 is a single-loop installation. It is also possible to divide the whole system into a series of sealed or closed units filled with a water and antifreeze solution operating on the gravity-flow principle. Each unit could

Electrically Heated Systems

Figure 7-36 Compact electric boiler.

Electrically Heated Systems

Figure 7-37 Single-loop installation consisting of electrically heated hydronic baseboard units. Water is circulated through the entire loop by a pump.

Be controlled by a thermostat, or several units by a wall thermo­stat. The advantage of this type of installation is that the heating capacity can be easily increased if the house or building is enlarged.

Posted in Audel HVAC Fundamentals Volume 1 Heating Systems, Furnaces, and Boilers