Rinnai Demand Rapid DD1200E315N Owner And Installer Manual page 8

Troubleshooting
troubleshooting without controllers or status monitor
Fault
Unit does not start
Unit starts and then shuts down
immediately
Unit starts then water goes cold
Excessive temperature
fluctuation while water is flowing
Excessive noise or vibration from
the water heater
Faults caused by insufficient gas and/or water supply, gas quality, water quality, installation errors
or operation errors are not covered by the Rinnai warranty.
Troubleshooting
general system troubleshooting
What's happening
Delivery temperature not
hot enough
Delivery temperature too
hot
Make-up water flowing
continuously
8 | Demand Rapid owner & installer guide 12949-B 02-19
Possible solution
Check power is on at the unit. Check gas isolation valve at the unit and gas
meter are fully open.
Check power is on at the unit. Check gas isolation valve at the unit and gas
meter are fully open.
Check power is on. Open hot water tap fully.
Service call.
Service call.
Possible cause
No electrical or gas supplies to the heat
source
Insufficient gas
Temperature sensor has dislodged or failed
Excessive load on system
Inadequate heating circuit—pump not
working properly
Tempering or thermostatic mixing valve
malfunctioning
Tempering or thermostatic mixing valve
malfunctioning
Leak in cylinder and/or heating circuit
Explanation and/or possible solution
Check and turn on the power and gas
supplies
Check gas supply, availability and pressure
Check temperature sensor is correctly
positioned and providing information to the
thermostat
Check maximum demand does not exceed
rated capacity
Check all valves are fully open
Service call
Service call
Check for leaks