77
13
Maintenance
(continued)
Check flame signal
1. At high fire the flame signal shown on the display should
be at least 10 microamps.
2. A lower flame signal may indicate a fouled or damaged
flame sense electrode. If cleaning the flame sense electrode
does not improve, ground wiring is in good condition,
and ground continuity is satisfactory, replace the flame
sense electrode.
3. See Section 3 - Troubleshooting in the Knight XL Service
Manual for other procedures to deal with low flame
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
specified 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 13B - Heat Exchanger Cleaning Kits.
1. Shut down boiler:
• Follow the “To Turn Off Gas to Appliance” instructions
for the boiler in Section 11 - Startup.
• Do not drain the boiler unless it will be exposed to
freezing temperatures. If using freeze protection fluids
in the system, do not drain.
2. Allow time for the boiler to cool to room temperature if
it has been firing.
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 field 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 flush boiler
thoroughly with clean water by using purging valves to
allow water to flow through the water make-up line to the
boiler.
12. Perform start-up and check-out procedures in the Check
Flame and Combustion - Section 11 - Startup of this
manual.
13. Replace the access cover and restore boiler to operation.
Table 13B
Heat Exchanger Cleaning Kit
* 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. 13-5). If damaged DO NOT reuse, the
rope gasket must be replaced. Consult factory
for replacement rope gasket.
DIR #2000585246 00
ROPE GASKET
CAUTION:
I
F GASKET IS DAMAGED
DO NOT
REUSE, THE GASKET MUST
BE REPLACED.
Figure 13-3
Rope Gasket - Heat Exchanger Door
5. Remove the condensate hose from the heat exchanger
end. Connect a field supplied 3/4" diameter hose to
a drain pan. Using field supplied means, cover the
refractory in the back of the combustion chamber of the
heat exchanger.
Model
Kit
Number
Part
Number
Component
Description
400 - 1000 100157628
100333410 Rear Refractory Cover,
10.75
"
Diameter
100208804 Rear Refractory Cover,
7.25
"
Diameter
100208309* Nylon 4" Wheel Brush*
100208310
1/4" x 12" Drill
Extension
100208311
1/4" x 24" Drill
Extension
