RELIEF VALVE
You must have a relief valve on your boiler. Water expands as it is heated. If there is no place for the water to expand into, water pressure will build up inside the boiler and system. Should this happen, the relief valve will automatically open at a
EXPANSION TANK
In a properly assembled system, the expanding water flows into a expansion tank. This tank should be of the correct size. The tank is filled with air. As the water expands it compresses the air in the tank to form an air pressure cushion. This
radiators if left in the system. It is possible for a tank to become
DIAPHRAGM TYPE EXPANSION TANK
The diaphragm type expansion tank
AIR ELIMINATING FITTING (AIR PURGER)
An air purger is used to remove excess air from the system. It is installed in the supply line. It will eliminate air from the water before it reaches the radiators and bleed off this air.
MAIN AIR VENT FOR DOWN FLOW SYSTEMS OR DIAPHRAGM TYPE EXPANSION TANK
Before a system is filled with water, there is air in the pipes and radiation units. Some of it will be trapped as the system is filled. It is possible to eliminate most of this air through the air vent on the radiation units. A main air vent will speed and simplify this. It should be installed on the highest point in the supply main when all radiation is below top of boiler.
AUTOMATIC FILL VALVE
For safe, efficient operation, a hot water system must be completely filled with water. Adding new water, when needed can be done manually (by use of a hand valve in the water supply line). This requires regular attention to the system's
needs. An automatic fill valve accomplishes this without attention. It is installed in the supply line on hot water boilers only.
The valve operates through water pressure differentials. It does not require an electrical connection.
DRAIN VALVE
This manual valve Provides a means of draining all water from the boiler and system. It is often installed in the %" tapping at the bottom of the end boiler section. Or it can be installed in a tee where the return line enters the boiler.
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