WarmlyYours PD Pro Snow Switch - Manual (Page 17)

Snow Switch ® Model PD Pro
Instruction Manual
23735 Rev. B 06/14 (800) 234-4239 http: www.networketi.com Environmental Technology, Inc. 17 of 30
SIT–6E SENSOR TESTING
If paving material or other residue adheres to the sensing elements, clean the surface with a
Scotch™ Brite Pad. Avoid using metallic or coarse abrasives or detergents.
Regardless of weather conditions, the functional operation of an installed SIT–6E sensor can be
determined using a digital voltmeter (DVM) and a 10-pound (4.54kg) bag of crushed ice as
described below.
1.
With the DVM set to the 100 VDC range, verify the sensor supply voltage by connecting
the negative (–) test lead to the sensor black wire and the positive (+) test lead to the
sensor red wire. A DVM reading between 23 and 28 VDC is acceptable.
2.
With the negative (–) test lead remaining in place, reconnect the positive (+) test lead to
the sensor white wire and confirm there is 22 to 28 VDC present. Both the HEAT LED
and the SNOW LED should be off.
3. Place the entire contents of the bag of crushed ice on top of the sensor and allow a time
lapse in excess of 20 minutes before observing that less than 2 VDC is indicated by the
DVM. Depending on ambient conditions, however, this might take only a few minutes, in
which case, that is not a problem. (A nominal temperature below 38°F or 3.3°C must be
detected before the sensor’s normally-open contact is closed. If the sensor surface
temperature was excessive prior to beginning this procedure, it will be necessary to
extend the cool-down time interval by as much as an additional 20 minutes.) Most
importantly, make sure both the HEAT LED and the SNOW LED come on. Record results
on page 2 of this manual.
4. With satisfactory results, control and sensor pre-operational testing is now complete.
Disconnect and remove all testing devices from the system.
5.
Once all post-installation testing is complete and with unit power off, restore all wiring
connections.
6. Re-install the face plate and clear plastic cover onto the control. Set the Hold-On Time
control dial to the desired setting.