I have a Rheem Rudd Commercial Gas Water heater, model G100-200. All of the lights on the System Sentinel come on as appropriate. The igniter lights the pilot light and the flame comes on, then goes off. We have polished the flame detector. Most of the time, the flame goes offer almost immediately, some times after 5 seconds, some times after 5 minutes. We do not know why it is working intermittently.