Hydronic Furnaces

In a hydronic furnace, water is first heated in a boiler or water heater and then circulated through the coils of a liquid-to-air heat exchanger connected to the furnace air handler (Figure 7-23).

Hydronic Furnaces

Hydronic Furnaces Hydronic Furnaces

Hydrotherm residential oil-fired hydronic boiler

подпись: hydrotherm residential oil-fired hydronic boilerHydrotherm residential MultiPulse AM Series Gas-fired hydronic boilers

Figure 7-20 Examples of boilers used in hot-water heating systems.

Heat is transferred from the water in the coils to the air inside the air handler compartment. A blower distributes the warm air through ducts to outlets in the different rooms of the house or building.

This type of installation is sometimes called a hydro-air heating system. Its operation is controlled by a centrally located thermostat working in conjunction with an aquastat or time delay. The

Hydronic Furnaces

Figure 7-21 Gas conversion devices used for changing from one type of gas to another. (Courtesy Honeywell Tradeline Controls)

Aquastat or time delay prevents blower operation until the water passing through the coils in the air handler has reached the temper­ature called for by the thermostat setting. In zoned systems, heat circulation is regulated by a motor-actuated damper located in or near the duct system or the air handler. The damper motor is con­trolled by a zone control panel.

A hydronic furnace must be equipped with an air filter to pre­vent dust and other matter from circulating through the ducts and passing into the rooms. The accessories used with hydro-air heating

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Hydronic Furnaces


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Hydronic Furnaces


Figure 7-22 A partial list of certification symbols for boilers.

Hydronic Furnaces

Boiler Air handler

Figure 7-23 Hydronic furnace.

Systems include an electronic air cleaner, a humidifier, and an air conditioning evaporator coil with a condensate pump.

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