25
17 - EQUIPMENT AND OPTIONAL ACCESSORIES
EXPANSION TANK
Expanding water flows into expansion tank. Tank should
be correct size. Tank is filled with air. As water expands it
compresses air in the tank to form air pressure cushion.
This “spring-like” cushion serves to maintain correct
operating water pressure regardless of water temperature.
This assures “full measure” of water, even in highest
radiation unit of system. It also prevents blowing off of
safety relief valve. Air in tank in beginning (with system
filled with cold water) is sufficient for proper operation.
Tank also serves as trap for excess air in system. Air
would cause gurgling in pipes and in efficient circulation in
radiators if left in system.
It is possible for tank to become “waterlogged” (filled with
water). It can also become overfilled with air. This can hap
-
pen after filling system with new water. Fittings provided on
tank and in line to tank are for bleeding off excess water or
air.
When installing this tank, it is important:
1.
Tank be higher than boiler top.
2.
Pipe to tank continuously rises up to tank (so air
can “bubble” up to it).
DIAPHRAGM TYPE EXPANSION TANK
Diaphragm type expansion tank takes place of conventional
expansion tank. Carefully read instructions packed with
your tank assembly.
Tank comes with 10-12 pounds per square inch air charge.
This is the same as pressure produced in system by
automatic fill valve. When system is first filled, tank will
contain little or no water.
As water is heated its pressure increases. It expands into
tank, compressing air in tank. Compressed air cushion
permits water in system to expand as temperature
changes. Diaphragm type tank can be mounted on air
purger fitting or at any convenient place in supply or return
line.
AIR ELIMINATING FITTING (AIR PURGER)
Air purger is used to remove excess air from system. It
is installed in supply line. It will eliminate air from water
before it reaches radiators and bleed off this air.
MAIN AIR VENT FOR DOWN FLOW SYSTEMS OR
DIAPHRAGM TYPE EXPANSION TANK
Before system is filled with water, there is air in pipes and
radiation units. Some of it will be trapped as system is
filled . It is possible to eliminate most of this air through
air vent on radiation units. Main air vent will speed and
simplify this. Install on highest point in supply main when
all radiation is below top of boiler.
AUTOMATIC FILL VALVE
For a safe, efficient operation, hot water system must be
completely filled
with water. Adding new water, when
needed can be done manually (by use of hand valve in
water supply line). Requires regular attention to system’s
needs. Automatic fill valve accomplishes this without atten
-
tion. Install in supply line on hot water boilers only. Valve
operates through water pressure differentials. It does not
require electrical connection.
DRAIN VALVE
Manual valve provides means of draining all water from
boiler and system. It is often installed in 3/4” tapping at
bottom of end boiler section. Or it can be installed in tee
where return line enters boiler.
WATER TEMPERATURE CONTROL
Water temperature limit control in relay is adjustable
and may be set as necessary. It may be set as low as
104°F (40°C), or as high as 220°F (104°C). This depends
on type and amount of radiation involved and weather
conditions.
CIRCULATING PUMP
Every forced hot-water system requires circulating pump.
Separate pump or zone valve is required for each zone,
if you have a two or more zone system. Pump must have
capacity to provide circulation required by your system.
Pump is connected into main just ahead of boiler. It is also
wired to electrical system.
VENT DAMPER
This product is automatic, motorized stack damper
developed to increase efficiency of heating system by
reducing standby losses from heating apparatus and
conditioned air space. Damper closes chimney vent
when burner is off and fully opens it when combustion is
required.
