24
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 pre-
determined pressure. This will relieve the strain on
the boiler and system. Run a pipe from the relief
valve outlet (pipe must be same size as outlet
and the open end must not be threaded) to an
open drain, tub or sink, or other suitable drainage
point not subject to freezing. Failure to do so may
cause water damage or injury should relief valve
release.
EXPANSION TANK
In a properly assembled system, the expanding
water flows into an 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 “spring-like” cushion serves
to maintain correct operating water pressure
regardless of water temperature. This assures
a “full measure” of water, even in the highest
radiation unit of the system. It also prevents
blowing off of the relief valve.
The air in the tank in the beginning (with system
filled with cold water) is sufficient for proper
operation. The tank also serves as a trap for
excess air in the system. The air would cause
gurgling in the pipes and inefficient circulation in
the radiators if left in the system.
It is possible for a tank to become “waterlogged”
(filled with water). It can also become overfilled
with air. This can happen after filling the system
with new water. Fittings provided on the tank and
in the line to the tank are for bleeding off excess
water or air.
When installing this tank, it is important:
1) That the tank be higher than the boiler top.
2) That the pipe to the tank continuously rises up
to the tank (so that air can “bubble” up to it).
equIpmeNt ANd optIoNAl ACCeSSoRIeS - WhAt theY do
DIAPHRAGM TYPE EXPANSION TANK
The Diaphragm Type Expansion Tank (EX-TROL)
takes the place of the conventional expansion tank.
Carefully read the instructions packed with your
EX-TROL Tank Assembly. The EX-TROL Tank
comes to you with a 10-12 pounds per square
inch air charge. This is the same as the pressure
produced in the system by the automatic fill valve.
When the system is first filled, the EX-TROL Tank
will contain little or no water.
As the water is heated its pressure increases. It
expands into the EX-TROL Tank, compressing
the air in the tank. This compressed air cushion
permits the water in the system to expand as the
temperature changes.
AIR ELIMINATING FITTING (Air Purge)
An Air Purger is used to remove excess air from
the system. It is installed in the supply line. It
will help to 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 vents on
the radiation units. A Main Air Vent will speed and
simplify this. It should be installed on the highest
point in the main when all radiation is below top
of boiler.
AUTOMATIC FILL VALVE
For safe, efficient operation, a hot water system
must be 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.
Summary of Contents for XEB-2
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