13
6 720 607 026
Fig. 10 - Characteristic Pilot Flame
(Pilot assembly shown without pilot hood)
MAINTENANCE AND SERVICE
REVIEW MAINTENANCE TABLE ON THE BACK OF THIS
MANUAL.
Approximately once a year, the 425 HN should be checked
and cleaned. To remove the front cover, first remove the
incandescent particle tray, then pull off the temperature
adjustment knob and unscrew and remove the plastic collar.
Pull main cover out toward you and lift up and out. THE
FOLLOWING OPERATIONS SHOULD BE PERFORMED
BY A QUALIFIED SERVICE PERSON:
Vent System:
Should be checked annually. Clean and repair
as needed.
Water Valve
(Part # 8707002649): The water valve on this
heater should be serviced periodically. Lubricate component
36 on page 18 with a small amount of silicon, faucet or
lithium grease every two years to keep its o rings fresh and
pushrod sliding smoothly. Every 3-5 years replace component
36 on page 18. The frequency will depend on the mineral
content of the water and conditions of use or whenever
signs of corrosion appear at the gas and water valve joint.
Periodically check that the water inlet filter (#27 on page
18) is clean as well. NOTE: If water valve is removed, be
sure to also inspect the o ring seal on the end of the right
hand side water pipe before re-installing. Lubricating the o
ring with lithium or faucet and valve grease is recommended.
Pilot Flame:
The pilot flame should burn with a clean, sharp,
blue flame and should resemble the diagram in Fig. 10. If
the flame is soft and yellow, the pilot burner orifice may
need to be cleaned or replaced. The pilot flame should be
approximately 2 inches long, extending past the flame sensor.
If the flame is too small, it will not reach the flame sensor
and the burners will not come on.
Main Burner Flames:
The main burner flames should be
blue, with a more intense blue cone in the center core. Yellow
flames could be a sign of wrong size gas orifices or dirty
burners, or a blockage on the heat exchangers fins. If some
burners have yellow flames while others have good flames,
it is likely that dust, lint or spider webs have partially clogged
the burner venturis. To clean the burners, contact a gas
service person.
Mineral Scale Build-up:
The 425 HN heater, when operated
at lower temperature settings, does not accumulate mineral
build-up. If however, the heater is used at the higher
temperature settings and the water has a high mineral
content, periodic descaling may be necessary. The heating
coils should be flushed with a descaling solution.
The
descaling is done only to the heat exchanger.
The
chemicals will damage the hydro-generator and other parts.
Consult your service person.
TROUBLE SHOOTING
Introduction
The 425 HN burners are activated by a water flow valve.
Numerous water related problems can cause this water valve
to malfunction such as: Insufficient water flow volume to
activate the burners at its minimum flow requirement; Dirt
in the water flow valve causing it to malfunction; Sediment
build-up in faucet aerators, or shower heads; Uneven
pressures between cold and hot. (with single lever faucets)
Plumbing cross overs. These water flow related problems
can cause the heater to deliver less than its full output, or
to fail to ignite or to shut down completely.
To clean the pilot burner and/ or the pilot orifice :
Turn
off the gas to the unit. Set the On/Off switch to Off (position
). Remove the cover of the heater. To do so, pull off
the temperature adjustment knob and unscrew and remove
the plastic collar. Pull main cover out toward you and lift up
and out. The pilot orifice should be cleaned or replaced.
Do
not enlarge the orifice.
Do not use any wire or sharp object to clean orifices. Natural
gas orifices are large enough that you can usually clean
them by blowing through them. LP orifices, on the other
hand, are too small to clean and should be replaced.
To access the pilot orifice, remove 2 screws holding pilot
assembly in place. Then loosen compression fittings to expose
pilot orifice.
3mm
Correct gap between pilot
burner tip and electrode tip
Piezo Electrode
Flame sensor
Piezo
Fig. 11 - Pilot burner with pilot orifice
(Pilot assembly shown without pilot hood)
PILOT ORIFICE
