77
12
Maintenance
(continued)
Check fl ame signal
1. At
high
fi re the fl ame signal shown on the display should
be at least 10 microamps.
2. A lower fl ame signal may indicate a fouled or damaged
fl ame sense electrode. If cleaning the fl ame sense electrode
does not improve, ground wiring is in good condition,
and ground continuity is satisfactory, replace the fl ame
sense electrode.
3. See Section 3 - Troubleshooting in the Knight XL Service
Manual for other procedures to deal with low fl ame
signal.
Review with owner
1. Review the Knight XL User’s Information Manual with
the owner.
2. Emphasize the need to perform the maintenance schedule
specifi ed in the Knight XL User’s Information Manual
(and in this manual as well).
3. Remind the owner of the need to call a licensed contractor
should the boiler or system exhibit any unusual behavior.
4. Remind the owner to follow the proper shutdown
procedure and to schedule an annual start-up at the
beginning of the next heating season.
The boiler contains ceramic fiber
materials. Use care when handling these
materials per instructions in the Service
Manual. Failure to comply could result in
severe personal injury.
WARNING
Cleaning boiler heat exchanger
For recommended materials; including brush, appropriate
extension(s), refractory cover, and detailed instructions see
Table 12B - Heat Exchanger Cleaning Kits.
1. Shut
down
boiler:
• Follow the “To Turn Off Gas to Appliance” instructions
for the boiler in Section 10 - Startup.
• Do not drain the boiler unless it will be exposed to
freezing temperatures. If using freeze prevention fl uid
in system, do not drain.
2. Allow time for the boiler to cool to room temperature if
it has been fi ring.
3. Remove the nuts securing the heat exchanger access
cover to the heat exchanger and set aside.
4. Remove the heat exchanger access cover, burner, and
gas/air arm assembly.
6. Use a vacuum cleaner to remove any accumulation on the
boiler heating surfaces. Do not use any solvent.
7. Brush the heat exchanger while dry using a nylon bristle
brush.
Caution:
DO NOT use a metal brush. Re-vacuum
the heat exchanger.
8. Finish cleaning using a clean cloth dampened with warm
water. Rinse out debris with a low pressure water supply.
9. Allow the heat exchanger to thoroughly dry.
10. Remove the fi eld supplied rear refractory cover from the
back of the combustion chamber of the heat exchanger and
reassemble.
11. Close isolation valves on piping to isolate boiler from
system. Attach a hose to the boiler drain and fl ush boiler
thoroughly with clean water by using purging valves to
allow water to fl ow through the water make-up line to the
boiler.
12. Perform start-up and check-out procedures in the Check
Flame and Combustion - Section 10 - Startup on pages 57
and 59 of this manual.
13. Replace the access cover and restore boiler to operation.
Table 12B Heat Exchanger Cleaning Kits
Model
Kit
Number
Part
Number
Component
Description
400
100157627
100140243
Rear Refractory Cover
100162565*
Nylon 4" Wheel Brush*
100162566
3mm Allen Wrench
100162568
1/4" x 24" Drill Extension
501 - 801
100157628
100140243
Rear Refractory Cover
100162565*
Nylon 4" Wheel Brush*
100162567
1/4" x 12" Drill Extension
100162568
1/4" x 24" Drill Extension
* Do NOT use a metal brush. Only use
the kit provided brush or an equivalent
replacement nylon brush.
CAUTION
Installation & Operation Manual
NOTICE
Rope gasket is intended for sealing combustion
(FIG. 12-5). If damaged DO NOT reuse, the
heat exchanger door must be replaced. Consult
factory for replacement heat exchanger door
(kit 100173794 and 100173799).
ROPE GASKET
CAUTION:
I
F GASKET IS DAMAGED
DO NOT
REUSE, THE HEAT EXCHANGER DOOR
MUST BE REPLACED.
Figure 12-5 Rope Gasket - Heat Exchanger Door
5. Remove the condensate hose from the heat exchanger
end. Connect a fi eld supplied 3/4” diameter hose to
a drain pan. Using fi eld supplied means, cover the
refractory in the back of the combustion chamber of the
heat exchanger.
