Error Code 99; Warning Code Il - Rheem RTG2-42 Troubleshooting Manual

Error Code 99

Explanation: Fan Motor is not creating enough ventilation. The venting system passed pre-purge,
but has failed during normal operation. At a minimum check the following:
1. Check for blockage of heat exchanger fins
2. Check heat exchanger flapper valve at vent connection of water heater moves freely.
3. Clean air intake filter.
4. Remove all obstructions. Check the vent termination on the outside of the building and
the flapper valve at the top of the heat exchanger
5. You may rule out the venting portion by temporarily disconnecting the vent structure
from the water heater. If this fixes the problem, then the issue lies in the venting. If this
does not fix the problem, then the issue lies in the blower motor or printed circuit board.

Warning Code IL

Explanation: Unit may have lime build-up inside heat exchanger. Drain and flush unit as follows:
1. Turn off the power and remote controller(s) to the water heater.
2. Turn off the gas and water shutoff valves.
3. Disconnect the unions above the shutoff valves. (This is not required if an "ISOLATOR
VALVE" is used in the water piping. See instructions provided with "ISOLATOR
VALVE" for further instructions.)
4. Connect temporary fittings with ½" barb fittings on one side and union on other side to
the inlet and outlet water connections.
5. Connect the pump hose outlet hose to the ½" barb fitting at the cold-water inlet fitting.
6. Connect the drain hose to the ½" barb fitting at the hot-water outlet fitting.
7. Pour approximately 5 gallons of virgin food grade white vinegar into a pail.
8. Place the pump or the inlet hose and the drain hose into the pail. A pond pump or similar
model can be used for this application.
9. Turn on the pump and allow solution to circulate for 45 minutes.
10. Turn off the pump and drain the vinegar from the pail. Fill pail with fresh water.
11. Turn on the pump and allow the water to circulate for 15 minutes.
12. Ensure full flow of water through the water heater.
13. Turn off the pump and drain the water from the pail.
14. Repeat steps 10 thru 15 if required to ensure full flow of water through heater
15. Remove the hose from the hose and adaptor fittings from the inlet and outlet connections.
16. Connect the unions back to the water heater fittings.
17. Remove water filter in inlet of water heater and remove any sediment or dirt.
18. Return filter to water heater and screw in filter.
19. Turn on the water shutoff valves and check for leaks.
20. Turn on gas shutoff valves, power and remote control.
21. Check and ensure safe operation and performance of the water heater.
SVC 810 Tankless Troubleshooting Manual
63