1. OD sensor Problem
  A. Verify the sensor is still fastened to the wall at its original location. I have seen situations where they were removed or relocated, and sometimes without the owner even being aware of it. Usually, by siding contractors or landscapers knocking them off the wall. If missing, the control should give an error code.
  B. Disconnect the OD sensor using the Ohms setting. Select the next scale above 10K or the closest one, provided it is above 10K. If your meter is self-scaling, choose ohms, and it will choose the correct scale.
  C. Make a note of this and compare this reading to the current outdoor temperature near the sensor. The reading should be close to the chart for the OD sensor.
  D. You will be able to read your ohms reading and see what temperature the ohms reading is returning by reading to the left to the temperature column. It may not be exact, but within a few degrees is fine.
  E. If reading is off, replace the sensor with the same type.

2. Check the wire
  A. Reconnect the sensor to the wire. At the boiler, remove the sensor wires from the boiler terminals
  B. Do the same test as you did on the sensor only, leave it connected to the wire. The reading should be pretty close. Compare to the chart.
  C. What changed in the basement? Did they add fluorescent lights or anything near the sensor wire that could affect its reading? If the sensor wire is wrapped with a small metal wrap, it is known as a shielded cable, and it should not be affected. Try replacing the sensor; the extra resistance may be affecting the sensor.

1. OD sensor problem
  A. Follow the same steps as #1. above

2. Check the wire
  A. Follow the same steps as #2A. Above, the sensor should be mounted outside on a North or East wall and above the snow level.
  B. Follow the same steps as #2B. above. If the reading is much different from the sensor alone reading, proceed to 2C..
  C. The wire should be a shielded cable. If not, how is the wire routed between the sensor and the boiler? It should run perpendicular (cross over) to line voltage wires, not parallel (beside, along) with them.
  D. Is the wire routed near an electrical breaker box, fluorescent lights, projection TVs, large screen TVs, or anything else that could interfere with the ohms reading? Please do not wrap the sensor wire around anything, including other wires or conduit with wires inside it.
  E. If using shielded cable, is a small amount of the metal coating unraveled and attached to a metal surface to ground it?. If not, it needs to be grounded.

2. Review the parameters
  A. Verify the ODR is not disabled   B. Verify all the parameters are set properly. To review parameter descriptions and settings Click Here.

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