Sequence Of Operation; General Instructions - Dunkirk DXL-125 Installation, Operation And Maintenance Manual

Thermostat actuates on call for heat, completing
circuit to control. Completed circuit to control will
first activate circulator and damper which will close
end switch inside damper. Completes circuit to
ignition system, ignition takes place.
In event boiler water temperature exceeds high
limit setting on boiler mounted high limit control,
power is interrupted between control system and
ignition system. Power remains off until boiler
water temperature drops below high limit setting.
Circulator continues to operate under this condition
until thermostat is satisfied.
In event flow of combustion products through boiler
venting system becomes blocked, blocked vent
safety switch shuts main burner gas off. Similarly, if
boiler flue-way becomes blocked, flame rollout safety
switch shuts main burner gas off. Figure 17. If
either of these conditions occur, DO NOT ATTEMPT
TO PLACE BOILER BACK INTO OPERATION.
CONTACT CERTIFIED SERVICE AGENCY.
!
WARNING
Label all wires prior to disconnection when servicing
controls. Wiring errors could cause improper and
dangerous operation.
Before seasonal start-up, have a certified service agency
check boiler for soot and scale in flues, clean burners and
check gas input rate to maintain high operating efficiency.
Verify proper operation after servicing
Service agency will verify system is filled with water to
minimum pressure and open air vents, if used, to expel any
air accumulated in the system. Check entire piping system
and, if any leaks appear, have them repaired.
Circulators need to be checked and maintained. Refer
to circulator manufacturer's instructions.
Inspect venting system at the start of each heating
season. Check vent pipe from boiler to chimney for signs of
deterioration by rust or sagging joints. Repair if necessary.
Remove vent pipe at base of chimney or flue and using a
mirror, check vent for obstruction and verify vent is in good
working order.
Boiler flue gas passageways may be inspected by a
light and mirror. Remove burner door. See Figure 17.
Place trouble lamp in flue collector through draft relief
opening. With mirror positioned above burners, flue gas
passageways can be checked for soot or scale.

SEQUENCE OF OPERATION

Figure 17
Integral Draft
Hood
Burner
Door
Burners
Orifices
Manifold

GENERAL INSTRUCTIONS

This procedure should be followed to clean flue gas
passageways:
1.
Remove burners from combustion chamber by raising
burners up from manifold orifices and pulling toward
front of boiler. See Figure 17.
2.
Disconnect vent pipe from draft hood.
3.
Remove top jacket panel.
4.
Remove combination flue collector and draft hood from
boiler castings by loosening nuts on hold down bolts
located on each side of collector. See Figure 17.
5.
Place sheet of heavy paper or similar material over
bottom of base and brush down flue passageways. Soot
and scale will collect on paper and is easily removed
with the paper.
6.
With paper still in place in base, clean top of boiler
castings of boiler putty or silicone used to seal between
castings and flue collector. Verify chips are not lodged
in flue passageways.
When cleaning process is complete, restore boiler
components to their original position. Use IS-808 GE
silicone (available from distributor) to seal around flue
collector and boiler castings.
19
- Blocked Vent Safety Switch, Roll-out
Safety Switch
Base
Jacket Base
Panel
240009041
P/N
Blocked Vent
Safety Switch
Rollout Switch
4 Section Boiler
Rollout Switch
2,3,5
Section Boiler
, Rev. C [04/30/2017]