Qualified-installer test values for a Snow Owl sensor connected to the SCA-DUAL / PD Pro.
This procedure is for a qualified installer using the SCA-DUAL / PD Pro manual. It involves powered measurements, and the heating system can activate during the test. Follow the manual’s electrical-safety and monitoring requirements; keep clear of line-voltage terminals and stop if smoke, an abnormal odor, or overheating occurs.
- Start with a clean, dry moisture-sensing grid.
- Measure DC voltage between the black and red sensor leads at the controller, with the meter’s negative lead on black. The manual specifies 23–28 VDC.
- With the sensor warm, above 38°F, and dry, measure between black and white. The expected reading is 22–28 VDC; SNOW and HEAT should be off.
- Cool the sensor temperature probe using the method in the manual. While the grid remains dry, SNOW and HEAT should remain off.
- Moisten the sensing grid. SNOW and HEAT should turn on, and white-to-black voltage should fall below 2 VDC.
- Allow the cold, moist sensor to warm above 38°F. SNOW should turn off, HEAT can remain on for hold-on time, and white-to-black voltage should return to 22–28 VDC.
Record results. After testing, disconnect power before restoring connections and covers, then restore the required hold-on setting. Do not transfer these voltage limits to an unrelated controller or sensor.
Sources
- Manufacturer instructions (publication 3508), PDF pp. 13–14.
