Problem:
Reliatel RTUÂ will not bring on the heat while connected to a CCP III.
Reliatel RTU will not bring on the cooling while connected to a CCP III.
Reliatel RTU brings on the heat in test mode
Reliatel RTU brings on the cooling in test mode
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Solution:
This could be a problem with RTEM module, The comm link going to the RTEM module or a problem with problem with the CCP III database.
This debug is only for constant volume Reliatel RTUs that connected to a CCP III panel.
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1st step - Update the CCP III
Connect to the CCP III panel with the VariTrac Software and backup the database.
Upgrade the CCP III to V4.20.344 or higher and then see if the RTU will bring on heat.
Proceed to step 2 if heat does not come on.
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2nd step – Head to the roof for a possible RTU problem
There have been instances where the economizer motor, RTEM board or modbus comm link prevents the RTU from bringing on the heat.
Most likely there is noise coming from the RTEM or a cabling problem causing a Modbus comm disruption within the Reliatel modules.
RTRM board outputs control the fan and heat directly and only needs the TCI card to get the commands for fan and heating commands.
One sign of this is that you will see the CCP III saying heat 1 and or heat 2 is on but the RTU is not heating
Power down the Reliatel RTU, then disconnect the J2 cable from the TCI card and power on.
Disconnecting the J2 connector eliminates comm problem with the rest of the boards and only has comm up between the RTRM and the TCI card connected
Power on the RTU to see if heat comes on.
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 3rd step - Corrupted CCP database
If all of the above does not fix the problem, then reset the CCP III back to factory defaults, wait for calibration to finish to see if the heat will come on.
Be patient and do not make changes to the CCP until the heat turns on or not.
You will need to re-program if the CCP panel if the heat comes on.
You can try restoring the CCP back up but if the backup is bad, chances that it work and slim.
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Status:
As designed