Condition
- The Control is reading a return sensor temperature higher than the supply sensor temperature. Condition must be present for at least 75 seconds for this error code to appear.
Possible Cause
- Flow through boiler reversed.
- Verify correct piping
- No boiler water flow.
- Verify that system is purged of air and that appropriate valves are open.
- Supply or return sensor defective/inaccurate
Flow through boiler reversed
No boiler water flow
Option 1
- Check supply temperature on the home screen and compare it to the water temperatur/pressure gauge. Should be very close.
- Check return temperature with a temp gauge on return pipe.
Option 2
- Meter the return sensor and supply sensor and compare the ohms reading to charts.
Note:
Return sensor is on the return pipe above the boiler circulator. Remove side panel to access. Supply sensor is in the supply pipe with access from the front swing open door. It is a duel sensor for high limit and system supply temperature. The sensor will have a 4 pin connector with 3 wires. Meter the Red J8-8 to grey wire J8-9 and compare ohms to chart below.
Supply or return sensor defective/inaccurate
