Issue:
UC400 on Blower coil, Fan-coil or Unit Ventilator keeps going into freeze avoidance mode.
Resolution:
Units with economizers expect to have either a local or communicated outside air temperature. If neither is valid, av/3, outdoor air temperature active will report 0F, which is below the default freeze avoidance setpoint of 35F. You can give it a false outdoor air temp by putting ai/8, outside air temperature local, out of service and set the value to something above the freeze avoidance setpoint. The freeze avoidance setpoint can be adjusted on the Tracer TU setup parameters page.
It seems that this issue also affects blower coils configured as heat pumps, even if there is no economizer present. If the heat cool mode is in heat, and the reversing valve is in the heating position, check the outdoor air temperature local. If it is out of service and set to 0F, change the value to 70F. Verify no alarms are present. The compressor should start when the DX cool request reaches 50 or 100%, depending on whether it is a single or two stage compressor. Heat Capacity Primary Status will also be above 0%. Heat Capacity will remain at 0%.
12/9/2016 SPA
Units with BV1 Supply Fan Command set to cycling will go into freeze avoidance if the outdoor air temperature is below the freeze avoidance setpt, the fan is off due to no load in the space and the unit is occupied. Any time the fan goes off, whether we are occupied or unoccupied, the unit will go into freeze avoidance. This is as designed.
Notes:
Changes:
Other Question/Problem/Cause Statements:
- UC400 blower coil keeps going into freeze avoidance mode.
- UC400 fan coil is stuck in freeze avoidance mode.
-
UC400 blower coil heat pump is not going into heat.
- UC400 Unit Ventilator going into freeze avoidance mode.
Facts:
- TRACER UC400
- Tracer UC400
Original wave: wave134095
Document Identifier: DOC-107249
Document Identifier: 107249