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Common Questions About Heating, Ventilation and Cooling
What is an expansion tank?
An expansion tank is used within a boiler heating system to allow the water within the closed system room to expand as it is heated. Without the expansion tank, the pressure would build within the system as the water was heated causing undue stress on the system components and creating a potentially dangerous situation.
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There are two types of expansion tanks that are used in hot water systems: standard tanks, and bladder tanks. With a standard tank the water will actually entire the tank as it expands. With a bladder tank the water will press against a bladder within in the tank and never come in contact with the air contained in the tank.
In a standard tank the water does touch the air. In some set-ups this can be a problem because the water will absorb the air from the tank and release it into the radiators at high points within the system. This causes several problems: radiators stop working and must be bleed, the expansion tank fills with water an must be drained, and make-up water must added to the system. Most of the time these problems can be solved by replacing the standard expansion tank with a properly sized bladder tank.