20
On a call for heat, the thermostat will actuate,
completing the circuit to the control. The
completed circuit to the control will first activate
the circulator and damper which will close an
end switch inside the damper. This action will
complete the circuit to the ignition system and
ignition will take place.
In the event the boiler water temperature exceeds
the high limit setting on the boiler mounted high
limit control, power will be interrupted between
the control system and the ignition system.
The power will remain off until the boiler water
temperature drops below the high limit setting.
The circulator will continue to operate under this
condition until the thermostat is satisfied.
In the event the flow of combustion products
through the boiler venting system becomes
blocked, the blocked vent safety switch will shut
the main burner gas off. Similarly, if the boiler
flue-way becomes blocked, a flame rollout safety
switch will shut the main burner gas off.
Figure
18.
If either of these conditions occur,
DO
NOT ATTEMPT TO PLACE THE BOILER BACK
INTO OPERATION. CONTACT A CERTIFIED
SERVICE AGENCY.
Before seasonal start-up, have a certified service agency
check the boiler for soot and scale in the flues, clean the
burners and check the gas input rate to maintain high
operating efficiency.
!
CAUTION
Label all wires prior to disconnection when
servicing controls. Wiring errors can cause
improper and dangerous operation.
Verify proper operation after servicing
The service agency or owner should make certain the
system is filled with water to minimum pressure and
open air vents, if used, to expel any air that may have
accumulated in the system. Check the entire piping system
and, if any leaks appear, have them repaired.
Circulators need to be checked and maintained.
Refer to the circulator manufacturer's instructions.
The venting system should be inspected at the start of each
heating season. Check the vent pipe from the boiler to the
chimney for signs of deterioration by rust or sagging joints.
Repair if necessary. Remove the vent pipe at the base of
the chimney or flue and using a mirror, check vent for
obstruction and make certain the vent is in good working
order.
The boiler flue gas passageways may be inspected by a
light and mirror. Remove the burner door.
Figure 21
. Place
a trouble lamp in the flue collector through the draft relief
opening. With the mirror positioned above the burners, the
flue gas passageways can be checked for soot or scale.
The following procedure should be followed to clean the
flue gas passageways:
1.
Remove the burners from the combustion chamber by
raising the burners up from the manifold orifices and
pulling toward the front of the boiler.
Figure 21
.
2.
Disconnect the vent pipe from the draft hood.
3.
Remove the top jacket panel.
4.
Remove the combination flue collector and draft hood
from the boiler castings by loosening the nuts on the
hold down bolts located on each side of the collector.
Figure 17
.
5.
Place a sheet of heavy paper or similar material over
the bottom of the base and brush down the flue
passageways. The soot and scale will collect on the
paper and is easily removed with the paper.
6.
With the paper still in place in the base, clean the top
of the boiler castings of the boiler putty or silicone
used to seal between the castings and flue collector.
Make certain that chips are not lodged in the flue
passageways.
NORMAL SEQUENCE OF OPERATION
GENERAL INSTRUCTIONS
Figure 18 - Blocked Vent Safety Switch, Roll-out
Safety Switch
Blocked Vent
Safety Switch
Rollout Switch
4 Section Boiler
Rollout Switch
2,3,5,6,7
Section Boiler
Intergral Draft
Hood
Base
Burner
Door
Burners
Orifices
Jacket Base
Panel
Manifold
