Sequence Of Operation - Dunkirk PWXL Installation, Operation & Maintenance Manual

Boiler Flue Passages
Under normal operating conditions, with the burners properly
adjusted, it should not be necessary to clean the boiler fl ue
gas passages. However, to assure trouble-free operation, we
recommend that you have the fl ue passages, burner adjustment,
and operation of the controls checked once each year by a
competent Service Technician.
Before the start of each season (or whenever system has been
shut down for some time) recheck the whole system for leaks
and recheck the boiler and vent pipe for leaks. Replace or patch
any boiler seals that are faulty.
Vent System
The venting of this unit is very important and should be checked
at least once a season. If the vent piping shows any sign of
leaking, replace it immediately.
Water System
If system is to remain out of service during freezing weather,
always drain it completely (water left in to freeze will crack the
pipes and/or boiler).
The Boiler uses an electronic control to maintain water
temperature and to monitor the critical water level. There
are four (4) LED indicators that will display the mode of
operation of the unit.
LOW WATER
TSTAT GREEN
HIGH LIMIT YELLOW
ACTIVE GREEN
There are four adjustable settings on the control. These can
be adjusted using a small screw driver or by turning the
adjusting post. When power is applied to the unit all LED's
will illuminate for a brief moment. The Active LED will
remain lit indicating that the control is powered and that
the temperature function is active. The display will then
cycle through the settings of the control.
CONTROL SETTINGS
Setting
HIGH TEMPERATURE LIMIT (HL)
HIGH TEMPERATURE
DIFFERENTIAL (H df)
LOW TEMPERATURE
DIFFERENTIAL (LL)
LOW TEMPERATURE LIMIT (L df)
MAINTAINING YOUR BOILER

SEQUENCE OF OPERATION

RED Low water condition
Thermostat call for heat
Water temperature at high
limit
Active, power to unit is on
Range ( F)
o
130°-220°
10°-30°
10°-30°
OFF or
110°-200°
Cleaning Your Boiler And Burners
Flue passages between sections should be examined yearly
and cleaned if necessary. To clean, remove burners, pilot, and
vent pipe, Remove top and front jacket panels. Remove the two
screws attaching the intermediate front panel to the left and right
side jacket panels. Remove the draft diverter and intermediate
front panel as a unit. Carefully remove the cerafelt gasket strips.
Clean passageways between sections with a fl exible handle wire
brush. Remove dirt from bottom of boiler and from between
sections by vacuuming. Make sure all fl ame ports in burners are
open and clear. Shake out or blow out all loose dirt in burners.
Reseal seams between adjacent sections as necessary with 400°
F RTV silicone sealant. Reassemble all parts. Be sure to check
tightness of pilot connections and condition of burner fl ames
after reassembly (see Figures 20 and 21). Be sure vent
pipe connections to chimney are secure and no obstructions are
present.
PWXL with Electronic Ignition
Upon a call for heat the room thermostat will close the
Green Thermostat LED will illuminate. Power will be
applied to the pump circuit enabling the fl ow of water to
the heating space. The automatic vent damper will then
begin to open. When the vent damper is completely open
the ignition module will start the ignition sequence.
At the start of the ignition sequence the pilot valve will
open and the spark controller will light the pilot burner.
Upon a successful proven pilot light the main gas valve will
open allowing the main burners to light. The burners will
continue to fi re until the call for heat is satisfi ed and the
thermostat opens or the water temperature in the boiler
reaches the High Temperature Limit setting.
When the water temperature reaches the High Temperature
Limit setting, while the thermostat is not satisfi ed, the
Yellow LED will illuminate and the circulator pump circuit
will remain energized. The gas valve will close, shutting
off the main burners. While the thermostat is calling, if the
water temperature falls below the High Temperature Limit
setting (minus) the High Temperature differential setting,
Factory
the ignition sequence will start again to maintain the boiler
setting
water temperature.
180°
If the Low Temperature Limit is active (not set to OFF)
10°
the control will maintain a minimum water temperature
allowing for warm start operation enabling the boiler to
readily satisfy the heat load.
10°
While the thermostat is NOT calling, the control will allow
OFF
the burner to fi re until the boiler water temperature
reaches the Low Temperature Limit setting (minus the Low
Limit Differential).
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