WattMaster Water Source Heat Pump, Installation & Operation Manual

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WattMaster WHP Section 4
4-24 Start-Up and Troubleshooting
5.3 Checking Comm. Loop Voltages
5.3.1 Checking the CommLink II Network Loop
Diagram
Overview
This test checks for proper Network loop voltages at the CommLink II.
Tip: The Loop LED (located on the front panel) should “flicker” when the CommLink II is
attempting to communicate. The Loop LED will flicker more noticeably for a few
seconds when first powered up. If the Loop LED does not flicker, the unit is defective.
Make sure CommLink II jumper is set to “Multi” position.
Proper loop voltages are essential for reliable communications. It is normal to see fluctua-
tions at this point on the CommLink II. The average value should be close to the acceptable
range described below. Values will vary upon initial powerup for about 10-15 seconds as
the unit attempts to communicate.
Measurements
Network Loop Acceptable Range
T - G (SHLD) 2.9 - 3.1 Volts DC
R - G (SHLD) 1.9 - 2.1 Volts DC
Action
Condition Action
If voltages are too high or too low on either
side 1. Unplug the Network loop from the
CommLink II and check for proper loop
voltages. If a problem exists, disconnect
each MiniLink Network loop until the
problem is isolated.
2. Check the CommLink II Driver chip.
Replace the driver chip if necessary