Pressure Switch; Rollout Switch - Dunkirk XEB-2 Installation Manual

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DRAIN VALVE
This manual valve provides a means of draining
all water from the boiler and system. It is often
installed in the ¾" tapping at the bottom of the left
boiler section. Or it can be installed in a tee where
the return line enters the boiler.
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.
The pump does not come pre-installed on the boiler.
It must be connected to the circulator harness in
the field according to the pump manufacturer's
instructions and the wiring diagrams in this
manual.
BLOWER (Draft Inducer)
The blower provides a means for pulling air
through the boiler and exhausting the flue gasses
into the vent system. The blower shuts off when
the burners are not firing. This keeps heat in the
house rather than having it go up the chimney.

PRESSURE SWITCH

The air pressure switch works on a negative
pressure. When the blower comes on the air
pressure switch operates the intermittent pilot
and gas valve. The air pressure switch is factory
set and will only work when the blower operates
properly. It will not allow the boiler to come on if
the blower does not generate enough pressure or
if the venting system is blocked.
FACTORY PRESSURE SWITCH SETPOINT:
-0.4" wc. for 2-5 section boilers.
-0.5" w.c. for 6-7 section boilers.

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 fire box. In the event of heat exchanger
flueway blockage causing flame to roll out of the
fire box, the fuse will blow, shutting down the flow
of gas to the main burners. 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
flueways for blockage when restoring system
to operating condition. Do not operate system
without a rollout switch.
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