20
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 predetermined 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
fl ows into a expansion tank. This tank should be of the
correct size. The tank is partially fi lled 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 a
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 fi lled with cold water)
is suffi cient 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 ineffi cient circulation in the
radiators if left in the system . It is possible for a tank
to become “waterlogged” (fi lled with water). It can also
become overfi lled with air. This can happen after fi lling 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:
That the tank be higher than the boiler top.
1.
That the pipe to the tank continuously rises up to the
2.
tank (so that air can “bubble” up to it).
Diaphragm Type Expansion Tank
The diaphragm type expansion tank (EXTROL) takes the
place of the conventional expansion tank. Carefully read
the instructions packed with your EXTROL tank assembly.
The EXTROL 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 fi ll valve. When
the system is fi rst fi lled, the EXTROL tank will contain little
or no water.
As the water is heated its pressure increases. It expands
into the EXTROL tank, compressing the air in the tank. This
compressed air cushion permits the water in the system to
expand as the temperature changes. The diaphragm type
tank can be mounted on the air purger fi tting or at any
convenient place in the supply or return line.
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 fi lled with water, there is air in the
pipes and radiation units. Some of it will be trapped as the
system is fi lled . 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, effi cient operation, a hot water system must
be completely fi lled 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 fi ll 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 3/4”
tapping at the bottom of the end boiler section. Or it can be
installed in a tee where the return line enters the boiler.
Circulating Pump
Every forced hot-water system requires a circulating pump.
This pump must have the capacity to provide the circulation
required by your system. The pump is connected into the
return main just ahead of the boiler. It is also wired to the
electrical system.
Vent Damper
This product is an automatic, motorized stack damper that
has been developed to increase the effi ciency of heating
systems by reducing standby losses from the heating
apparatus and the conditioned air space. The damper
closes the chimney vent when the burner is off and fully
opens it when combustion is required.
Rollout Switch (Flame Rollout Safety Shutoff)
The rollout switch is a temperature-sensitive fuse link
device. It is located on the boiler base just outside the
fi re box. In the event of heat exchanger fl ueway blockage
causing fl ame to roll out of the fi re box, the fuse does not
change in appearance when blown. If the rollout switch
blows, it must be replaced with an exact replacement.
Check heat exchanger fl ueways for blockage when
restoring system to operating condition. DO NOT operate
system without a rollout switch.
EQUIPMENT AND OPTIONAL ACCESSORIES
