24
UnderfLoor ModUfLex ControLLer - Manual
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Underfloor ModUflex Controller
MAINTENANCE
Fault
Solution
Controller appears to be not
responding or have no power.
Green light on the controller is
not blinking. Thermostat green
indication light not on, or LCD
screen is blank.
Check thermostat first for either green indication light, or LCD display. If either of these does not appear,
then check the controller for power (green blinking light). If no power is present, check 24VAC power with
a multimeter. Cycle power to the controller. If this doesn’t restore power, check the power that is feeding
that controller for your problem.
Dampers don’t move, and red
FAULT light is illuminated.
Red fault light means there is a short in the cable from CW/CCW to COM. Find shorted cable(s) in that
string of dampers and replace.
Damper acts erratically
If the CW/CCW lines in the cable are shorted together (and not shorted to the COMMON), it could cause
the dampers in a string to act erratically and drive in random directions.
Find bad cable(s) in the string, and replace.
24 VAC Binary Outputs not
functioning
Ensure that the controller has 24VAC power.
Ensure that there is a call for heating or for cooling, room lights, etc. If so, check to see that the GREEN
indication light is on for the output.
The next step would be to check the device that is triggering the output like a relay. Ensure that the relay
has engaged (pulled in) for either heating or cooling application.
Check the output configuration
Analog Outputs not functioning
Ensure that the UMC3 has 24VAC power. Check the analog output for voltage with a multimeter. You
should see a voltage in the range of 0-10VDC.
Direct Acting Output – 0VDC indicates that the field device is closed or at a minimum position. 10VDC
indicates that the field device is open or at a full open position. Direct Acting is typical with cooling
applications.
Reverse Acting Output – 0VDC indicates that the field device is fully opened or maximum position, and
10VDC indicates fully closed or minimum position. Reverse acting is typical with heating applications.
SAT Sensor Analog Input not
functioning
Ensure that there is a sensor wired to the input on the UMC3 controller. Check the type of sensor, should
be a 10k Ohm Type Thermistor.
BACnet Communication Errors
BACnet - MS/TP is based on a RS-485 network. It must be wired in a daisy chain configuration. A daisy
chain means that there is only one main cable, and every network device is connected directly along its
path.
DO NOT use Star, Bus, “T”, or any other type of network configuration. Any of these other network
configurations will result in an unreliable network, and make troubleshooting almost impossible.
Correct polarity is imperative on MSTP wiring. Always ensure that the positive terminal on a device has
the same color wire connected to it throughout the network, same for the negative terminal. Eg. 2 wire
conductor with black and white wires – black to the positive terminal, and white to the negative terminal.
Keep this consistency throughout the network.
troubleshooting
The following information is provided in the event that the UMC3 does not appear to function properly after installation.
