Water fed boilers remains an integral part of heating systems, especially in northern climates. Boilers are still used widely in both residential and commercial applications. But one problem with using a boiler is premature failure due to corrosive elements.
When it produces steam, dissolved oxygen attaches to metal parts on the interior of the boiler. As with car rust, oxygen can act as a catalyst with other corrosive gases to erode the interior walls and other metallic parts. Carbon dioxide released from water can combine with oxygen to form a corrosive acid.
To prevent early failure of the tank, methods are utilized to remove dissolved oxygen from the system. One method is called a tray deaerator. In this system, feed water, or water entering the boiler, is sprayed with steam. As the water heats, it runs through layers of perforated metal trays. Dissolved oxygen and carbon dioxide collect on the trays and are subjected to further steam.
The trays are then stripped of the gases and oxygen and carbon dioxide are vented to the outside air. The deaerated water then falls to the bottom of the boiler tank and is forced through the heating system. Since the treated water removes corrosive gases prior to entering the heating system, heating pipes are also protected.
A deaerator system may be an integral part of the boiler tank or as a separate tank positioned on the top or side of the boiler. Trays may be stacked horizontally or vertically, depending on the configuration. Instrumentation monitors water pressure, temperatures, water flow and other vital components of the process. The trays and steam valves have a useful life of approximately 20 years. A full service dealer often has a wide inventory of replacement trays and valves. Since the tank with a quality deaeration system can normally have a longer useful life, replacing trays or spray nozzles is a far less expensive procedure than replacing an entire boiler.