Freeze Protection - Trane CGAM Installation & Operation Manual

Installation - Mechanical

Freeze Protection

Depending on the ambient temperature the unit may be
exposed to, there are up to four different options for freeze
protection.They are listed in order of highest ambient
(least freeze protection) to lowest ambient (most freeze
protection).
1. Water pump (for protection with ambient
temperatures down to 0°F)
a. CH530 controller can start the pump when the
ambient temperatures drops to prevent freezing.
For this option the pump must to be controlled by
the CGAM unit and this function must be validated.
b. Water circuit valves need to stay open at all times.
Note: If dual high head pump package option is
selected, the chiller MUST control the
pumps.
OR
2. Heaters (for protection with ambient temperatures
down to -20°F)
Note: This option is not applicable for units ordered
with "No Freeze Protection" (model number
digit 18 is "X"). Factory mounted heaters are
NOT installed on these units, and one of the
other forms of freeze protection must be used.
a. For units with freeze protection selected (model
number digit 18 is "1"), heaters are factory-installed
on the evaporator and water piping and will protect
them from freezing in ambient temperatures down
to -20°F (-29°C).
b. Install heat tape on all water piping, pumps, and
other components that may be damaged if exposed
to freezing temperatures. Heat tape must be
designed for low ambient temperature
applications. Heat tape selection should be based
on the lowest expected ambient temperature.
NOTICE:
Equipment Damage!
All heaters have separate power from the unit. All
heaters must be energized or the CH530 must control
the pumps when the unit is off (unless the water circuit
is drained). In the event of power loss, neither heaters
nor CH530 control of the pumps will protect the
evaporator from catastrophic damage. In order to
provide freeze protection in the event of a power loss
you MUST drain the evaporator or use sufficient freeze
inhibitor in the evaporator.
50
OR
3. Freeze inhibitor
• Freeze protection can be accomplished by adding
sufficient glycol to protect against freezing below
the lowest ambient expected.
• See "Low Evap Refrigerant Cutout/Percent Glycol
Recommendations, " p.
OR
4. Drain water circuit (for protection with ambients below
-20°F)
a. Shut off the power supply to the unit and to all
heaters.
b. Purge the water circuit.
c. Blow out the evaporator to ensure no liquid is left in
the evaporator.
Note: By default the CH530 freeze protection control is
enabled and will request the start of the chilled
water pump with ambient temperatures less than
the evaporator low leaving water temperature
setpoint.The pump remains ON until the minimum
evaporator water temperature is greater than low
leaving water temperature setpoint plus 7°C.The
minimum on time for the pump is 5 minutes. If you
do NOT want the CH530 to start the pump when the
ambient temperature drops to freezing, disable this
freeze protection control.
Low Evap Refrigerant Cutout/Percent
Glycol Recommendations
The table below shows the low evaporator temperature
cutout for different glycol levels.
Additional glycol beyond the recommendations will
adversely effect unit performance.The unit efficiency will
be reduced and the saturated evaporator temperature will
be reduced. For some operating conditions this effect can
be significant.
If additional glycol is used, then use the actual percent
glycol to establish the low refrigerant cutout setpoint.
50.
CG-SVX17E-EN