I was working on a VariTrac system at a bank today. It said RTU1 was in heat failure. I shut down the Trane YCD RTU (ReliaTel Controls) and put it into test mode. The heat worked fine on both stages. I reset the alarms on the Varitrac but another heat failure code came.
1. There wasn't a call for heat from the Varitrac because the VAV's wanted cooling.
2. The heat fail according the varitrac book says that a high temperature limit tripped in the RTU.
3. According to the ReliaTel controls book the high limits will still shut down the heat if they are open during the test mode. I cycled the unit through the test mode and after the last stage of heat, I shorted the test terminals again and it shut off the heat and turned the blower right back on. So I don't think there would have been enough residual heat to trip the high limits.
4. I'm wondering if it's something with the communication because it was 80 some degrees and the vav's wanted cooling. I shouldn't have had a call for heat and when I put it through test mode the high limit wasn't tripped or otherwise the heat wouldn't start. My flame signal was 6 Microamps.
Any help would be appreciated.