Rinnai REP199i Installation And Operation Manual page 51

Scale Build-up in Heat Exchanger
lc
(when checking maintenance code
history, "00" is substituted for "LC")
• LC indicates that there is scale build
up in the heat exchanger and that
the heat exchanger needs to be
flushed to prevent damage. Refer
to the flushing instructions in the
manual. Hard water must be treated
to prevent scale build up or damage
to the heat exchanger.
• After flushing, reset LC code as
instruction.
• Please call Rinnai technical
department.
Maintenance Indicator
FF
• Placeholder in Diagnostic code
history indicating that a service
provider performed maintenance or
service.
• Enter this code after performing
service by pressing  (Up) , 
(Down) and On/Off simultaneously.
FF is visible on the monitor.
•
(SS) Service Soon (Flush Heat
SS
Exchanger)
SS is a time-based service indicator
•
set during installation. See section
"4.10 Configure Parameter Settings"
for additional details on setting and
changing the SS indicator.
SS indicates that it is time for service.
•
The heat exchanger should be
flushed to prevent damage (refer
to section "6.2 Flushing the Heat
Exchanger" for more information).
Hard water must be treated to
prevent scale build-up or damage
to the heat exchanger.
• To reset the SS code, push the On/Off
button on the temperature controller
5 times in 5 seconds.
Rinnai Tankless Water Heater Installation and Operation Manual
FF
NO CODE - Nothing happens when water
flow is activated
• Clean inlet water supply filter.
• On new installations ensure hot and
cold water lines are not reversed.
• Verify you have at least the minimum
flow rate required to fire unit.
• Check for cold to hot cross over. Isolate
circulating system if present. Turn off
cold water to the unit, open pressure
relief valve; if water continues to flow,
there is bleed over in your plumbing.
• Verify turbine spins freely.
• Measure the resistance of the water
flow control sensor.
• If the display is blank and clicking is
coming from the unit, disconnect the
water flow servo motor (GY, BR, O, W,
P, BL, R). If the display comes on then
replace the water flow servo motor.
* See "Electrical Diagnostics" on Technical Data
Sheet located on inside front cover of water heater.
51