Dunkirk PVWB, Installation Instructions Manual

Page: 14 / 24

14
Equipment and Optional Accessories - What They Do
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 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 “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 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).
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.
The diaphragm type tank can be mounted on the air purger
fitting 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 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 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 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 boi
l
er.
WATER TEMPERATURE CONTROL
The water temperature limit control in the relay is adjustable
and may be set as necessary. It may be set as low as 140°F,
or as high as 240°F. This depends on the type and amount of
radiation involved and weather conditions.
CIRCULATING PUMP
Every forced hot-water system requires a circulating pump. A
separate pump or zone valve is required for each zone, if you
have a two or more zone system. This pump must have the
capacity to provide the circulation required by your system.
VENT DAMPER
This product is an automatic, motorized stack damper that has
been developed to increase the efficiency of heating system
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.