Paloma PH2-20R OFN Engineering Handbook page 11

Indoor ONLY
Venting:
13
Flame Rod FL-2: Reads
Poor Or Improper
Combustion
Condensing only:
Maintenance:
Flue Temperature Too
High
14
Mid Efficiency &
Condensing:
Over Heat Limiter (OHL)
Fault
Maintenance:
Boiling Safety Device
(Heat Exchanger
15
temperature reached
207 F degrees for more
than 15 seconds)
Maintenance:
Outlet Water
16
Temperature Is Above
Remote Thermostat
Setting
SVC 820-Tankless Gas Trouble Shooting Manual
Ensure intake and exhaust venting meet all installation requirements (diameter; vent
lengths; venting material; venting obstructions; and all other requirements as
described in the Use & Care manual {Make sure exhaust is not recirculating into fresh
air intake})
If venting requirements are met:
1. Remove any blockage from venting or from in front of vent termination
2. Verify altitude settings
3. Check Flame Rod FL-2
4. Check Blower Motor
Condensing Only:
1. Clean blockage in heat exchanger
2. Remove any blockage from Blower Motor and exhaust vent
Mid Efficiency & Condensing:
If 'Condensing' maintenance requirements are met:
1. Verify "U" connector is connected to Control Board
2. Verify wiring harness is connected to OHL
3. Check heat exchanger for cracks and/or separations
4. Inspect Overheat Wrap (Overheat wrap failure: Replace unit)
5. Check thermal overload sensor (condensing models only)
1. Flush Heat Exchanger (lime/scale buildup)
2. Check for closed water heater inlet valve or restrictions in cold water inlet
pipe (must be fully open)
3. On commercial water heater, lower set point temperature below 180
high altitudes
If maintenance requirements are met:
1. Check Heat Exchanger Thermistor
1. Check for clogged Heat Exchanger
2. Check for restrictions in airflow around unit and vent terminal
If maintenance requirements are met:
1. Check Outlet Thermistor
2. Check Heat Exchanger Thermistor
3. Check gas valve
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