VAV-SVX07F-EN 67
Troubleshooting
• Heat relays have failed.
– The UC400 controller will call for the valve to be OPEN, (viewed in the Status screen). If not,
check the TRIAC output, wiring connections, and relay output.
– If the UC400 controller is calling for the heat output to be
ON (viewed in the Status screen),
then the LED is OFF for the correc
t Binary Output 7 to open the valve (note, polarity is
reversed on this point). If the TRIAC is not closed, then check the UC400 controller TRIAC
output, wiring connections, and relay output.
– Check for correct binary outputs. It should have 24 Vac. If it does not, measure the power
in
put to XFMR 24 V
ac input and of the UC400 controller. The supply voltage should be
between 20.4 to 27.6 Vac (24 Vac cataloged). However, voltages at
either extreme may result
in system instability.
NOTICE:
Equipment Damage!
The UC400 controller outputs are switched to ground. Do not jumper 24 Vac to binary output
TRIAC(s) because damage will occur.
• Heat TRIAC(s) can be checked by purchasing a 24 Vac LED and connecting to the TRIAC output.
If they are lit, it is calling heat output to be OPEN or CLOSED by the UC400 controller. If LED is
not lit, replace the UC400 controller.
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