61
12
Maintenance
(continued)
Cleaning heat exchanger
1.
Shut down water heater:
• Follow the “To Turn Off Gas to Appliance” instructions
for the water heater on pages 49 and 50.
• Do not drain the water heater unless it will be exposed
to freezing temperatures.
2.
Allow time for the water heater to cool to room
temperature if it has been firing.
3.
Remove the blower assembly (gas air/arm) from the heat
exchanger access cover. Set bolts aside.
4.
Remove the nuts securing the heat exchanger access cover
to the heat exchanger and set aside.
5.
Remove the heat exchanger access cover, cover gasket(s)
and chamber insulation assembly.
The water heater contains ceramic fiber
materials. Use care when handling these
materials per instructions listed on this
page. Failure to comply could result in
severe personal injury.
11. Close isolation valves on piping to isolate water heater from
system. Attach a hose to the water heater drain and flush
water heater thoroughly with clean water by using purging
valves to allow water to flow through the water make-up line
to the water heater.
12. When the water heater has been flushed, restore water
heater to operation.
13. Perform start-up and check-out procedures listed in Section
10 - Start-up.
Oiled bearing circulators
1. The circulator shipped with the Shield water heater is water-
lubricated. No oiling is required.
2. Check other circulators in the system. Oil any circulators
requiring oil, following circulator manufacturer’s
instructions. Over-oiling will damage the circulator.
WARNING
Installation & Service Manual
TM
Avoid breathing dust and contact with skin and eyes.
• Use NIOSH certified dust respirator (N95). This type of
respirator is based on the OSHA requirements for
cristobalite at the time this document was written.
Other types of respirators may be needed depending on
the job site conditions. Current NIOSH
recommendations can be found on the NIOSH website
at http://www.cdc.gov/niosh/homepage.html. NIOSH
approved respirators, manufacturers, and phone
numbers are also listed on this website.
• Wear long-sleeved, loose fitting clothing, gloves, and eye
protection.
Apply enough water to the combustion chamber lining to
prevent airborne dust.
Remove the combustion chamber lining from the water
heater and place it in a plastic bag for disposal.
Wash potentially contaminated clothes separately from
other clothing. Rinse clothes washer thoroughly.
NIOSH stated First Aid.
Eye: Irrigate immediately.
Breathing: Fresh air.
Magnesium anode rod inspection
Glass lined storage tanks have a magnesium anode(s)
(FIG. 12-3) to provide cathodical protection of the lining and
minimize corrosion. Aggressive water conditions in some areas
of the country may accelerate the deterioration of the anode(s).
The anode(s) should be periodically removed and inspected to
determine if replacement is necessary.
The heater must be valved off from the system and fully drained
to remove an anode for inspection. Anodes are supplied in
threaded fittings on the side of the tank. Adequate service
clearance is required to allow removal of an anode. The
anode(s) should be replaced when more than six inches of the
core wire is exposed at either end of the rod.
6. Use a vacuum cleaner to remove any accumulation on the
water heater heating surfaces. Do not use any solvent.
7. Finish cleaning using a clean cloth dampened with warm
water.
8. Install access cover gasket, chamber insulation assembly
and cover.
9. Secure nuts on the studs. DO NOT overtighten.
10. Re-install the blower assembly (gas air/arm) using the
bolts set aside in Step 3.
Figure 12-3
Anode Location
NOTICE
Anode rods showing excessive
decomposition may indicate electrolysis. An
earth ground should be attached to the vessel
to divert stray current and prevent tank
damage.
Check Delta T
1.
Ensure Delta T is less than 25°F.
