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SCPM troubleshooting


1. High limit sensor is not installed.

2. GFI is tripping.

3. System is partially heating.

4. Noisy contactor.

5. Temperature reading errors

6. Communication errors

7. Power light OFF, display OFF

8. Power light ON, display OFF





Common questions and answers about specific setting in the setup.

To enter the programming settings, put DIP switch 1 in the ON position. Programming DIP switches are on the back side of the small controller, on the back side of the door.

1. Disable P02 and P03 in the programming settings.

2. a. If they use Relay Panels and no heating cables/mats are connected directly to the SCPM, disable the GFI by disconnecting the current transformer. To do this they need to disconnect the two wires from the green terminals on the upper left corner of the GFS - ground fault sensor. The GFS is the black device inside the control, positioned on the lower-middle right side.

b. If the mats/cables are connected directly to SCPM, reset the GFI by pressing and holding the Red button on the door for 5 seconds. If the GFI is tripped again or it doesn't reset, disconnect all the wires and test them with a Megohmeter and a Multimeter. If they don't have them, then connect one wire at a time and see which one trips the GFI. Every time they connect a wire, turn the unit OFF, connect the wire, turn the unit back ON and put it in manual mode.

3. a. Check if all used zones are activated. To do that, press the + and - button at the same time for about 10 sec. Check if all the used zones are active (black). Default the 4th zone is disabled and the 5th is enabled. If they use all contactors, make sure that all 5 zones are enabled. To activate/deactivate the zones, press Select to scroll between them and the +/- buttons to enable/disable the zone.

b. Check if they have voltage on the output H1.x, H2.x - 120V for relay panels and 120V/240V for cables/mats.

4. Determine which contactor is noisy and replace it.

5. Ambient temperature sensor readings (on snow sensor) are out of reliable measuring range: Ambient temperature < -9°F/-23°C or Ambient temperature > 54°F/12°C. The system will continue to operate using constant predefined values. In addition, the display will alternate between “LO” and -11°F/-24°C for low temperature readings, and between “HI” and 55°F/13°C for high temperature readings.

6. Error 1 – Communication error with one (or more) snow sensors “SensErr 1” Will appear on display. If the system is configured to work with more than 1 snow sensor, the faulty snow sensor number will appear on display: P01, P02, P03 or P04. The system will use readings from snow sensor 1 instead of the missing readings from the faulty snow sensor.

Error 2 – Upper limit temperature sensor is not connected or short circuit “SensErr 2” Will appear on display. The system will continue to operate regardless of the upper limit temperature. Required actions: 1. Refer to P03 section of the technician settings.

2. Check the temperature value and disable the sensor if needed.

3. Disconnect the sensor and test it (ohms reading), acceptable range is +/- 10,000 Ohms depending on temperature.

4. If the sensor is damaged, replace the sensor

7. Verify 120 Vac between L1 and N1.

8. - Reinstall connections at rear of the controller

- Verify 24 Vac between terminals R and C (top two terminals, back side of the SCPM controller)

- If 24 Vac is present between terminals R and C, then the controller is faulty

- If there is 120 Vac on terminals L1 and N1, and 0 Vac between R and C, remove and test the fuse in the black casing with a digital ohm meter-FUSE T2AL250V (2 Amp, 250V – small glass fuse)

9. - Verify GFS (Ground Fault Sensor) is set for 30 mA.

- Press Ground Fault Reset button for 3 seconds.

- If the light is still ON – disconnect the load wires and press the Ground Fault Reset button for 3 seconds.

- If the light is still ON – check the connections between the inside GFI test button and the Ground Fault Sensor.

- Re-connect load wires one-by-one, until GFR light comes on. Test offending wire with Digital Multimeter or Mega Ohm-meter.

10. - Test for amp draw on the load wires with a clamp amp meter.

- If there is no amp draw, verify 120 Vac or 240 Vac is present at the top of the wire terminals of the zone that is calling for heat (Terminals H11-H25)

- Verify proper ohms readings of affected heating cables

11. - Verify 24 Vac between the red and the white wire attached to the coil of the contactor, found on the left and right side of the contactor.

- If 24 Vac is NOT present, verify 24 Vac on brown wires exiting green power transformer.

- Verify connection between wire and its connector.


P03- when on indicates 100 in small font and 1 to 13 in large font  I have it disabled as the manual indicates that it should default to 86F.  Is the manual out of date or does the firmware need to be updated? The 100 should be added to the value in the 2 digits. Basically you should see the 100 whenever the value is >100 but if you press the “-“ button, after you will reach the 01, the 100 will disappear and the 2 digits will decrease from 99 down.


P04- if I leave it to the default of 30 mins and the heaters are on ( P06 =240mins) will the system turn off after 30 mins or after the P06 reading?

P[04] define the time that the system keeps running after the snow stops (meaning the time after the snow sensor no longer detects snow). The system will turn OFF 30 minutes after the sensor is no longer detects snow, regardless to the P[06] value.


P05- default of 6 hrs, will the mats stay on for 6 hours even if P06 is set for 2 hours or P04 is set for 30 mins?

P[05] is the overall time that the system will activate the heaters in manual mode, before returning (automatically) to AUTO Mode. Pressing the “Select” button activate the system in Manual mode for the P[06] time, regardless to the P[04] value. The system will work and the staggering sequence will be calculated for the whole P[05] time according to the P[06] time.


Why does Mat 4 and Mat 5 show up together when I use default zones?

That was the design of the system. Either zone 5 (30A output) will work separately by different sensor or work with zone 4 as a pair. The idea was to have the zones 1-4 for the snow melting and have zone 5 just for gutter or small surface that is critical that could be monitored and controlled separately from the zones.


Please see attached Image.  Why is there a lower and higher termination block? 

The only way I could get the replays to work correctly was to connect 120VAC to the top *bottom( strip) even though your factor connections were on the bottom (upper strip).

The left terminals are the feed line (L) while the right (2 stories height) are for the heaters (H)

I believe that according to the text, you connected otherwise but even though, the system should work OK.

Written by Gabriel Taut
Posted on
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