Low Evaporator Refrigerant Cutout, Glycol Recommendations; Procedure; Specials - Trane R Series Installation, Operation And Maintenance Manual

Installation - Mechanical
temperature provided power is available to the
pump and the CH530 controller.This option will
NOT protect the evaporator in the event of a power
failure to the chiller unless backup power is
supplied to the necessary components.
Note: When no chiller operation is possible and the pump
is already off, CH530 pump control for freeze
protection will command the pump to turn:
• ON if liquid level > -0.83" in AND evaporator
saturated temp < Leaving WaterTemperature
Cutout (LWTC) for 30°F-sec (17°C-sec)
• OFF again if evaporator saturated temperature
> LWTC OR liquid level < -0.83" for 30 minutes.
• ON if entering OR leaving water temperature
< LWTC for 30°F-sec (17°C-sec)
• OFF again if water temperature > LWTC for 30 min
OR
2. Freeze inhibitor
a. Freeze protection can be accomplished by adding
sufficient glycol to protect against freezing below
the lowest ambient expected.
b. See " , " p. 53 for guidance on determining glycol
concentrations.
Note: Use of glycol type antifreeze reduces the cooling
capacity of the unit and must be considered in the
design of the system specifications.
OR
3. Drain water circuit (for ambients below -20°F)
a. Shut off power supply to unit and to all heaters.
b. Purge the water circuit.
c. Blow out the evaporator to ensure no liquid is left in
the evaporator.
NOTICE:
Evaporator Damage!
If insufficient concentration or no glycol is used, the
evaporator water flow must be controlled by the CH530
AND heaters must be used to avoid catastrophic
damage to the evaporator due to freezing. It is the
responsibility of the installing contractor and/or the
customer to ensure that a pump will start when called
upon by the chiller controls. Refer to RLC-PRB012-EN.
Even with water pump control, a power loss of as little
as 15 minutes under freezing conditions can damage
the evaporator. Only the proper addition of freeze
inhibitor or complete drainage of the water circuit can
ensure no evaporator damage in the event of a power
failure. See Table 27, p. 54
glycol.
RTAC-SVX01J-EN
for correct concentration of
Low Evaporator Refrigerant
Cutout, Glycol Recommendations
1. Solution freeze point is 4 deg F below operating point
saturation temperature.
2. LRTC is 4 deg F below freeze point.

Procedure

1. Is operating condition contained within
If no, see "Specials, " p.
2. For leaving fluid temperatures greater than 40 deg F ,
use settings for 40 deg F .
3. Select operating conditions from
4. Read off recommended % glycol.
5. Go to Table 28, p. 54
above.
Important: Additional glycol beyond the
recommendations will adversely effect unit
performance. Unit efficiency and saturated
evaporator temperature will be reduced.
For some operating conditions this effect
can be significant.
6. If additional glycol is used, then use the actual % glycol
to establish the low refrigerant cutout setpoint.
7. The minimum low refrigerant cutout setpoint allowed
is -5 deg F .The minimum is established by the
solubility limits of the oil in the refrigerant.

Specials

Any of the following conditions are considered special
applications that must be calculated by engineering:
1. Freeze inhibitor other than ethylene glycol, propylene
glycol, calcium chloride or methanol.
2. Fluid deltaT outside the range 4 to 16 deg F .
3. Unit configuration other than Standard, Standard with
extra pass, and Premium.
4. % Glycol greater than maximum in column in
Special should all be calculated by engineering.The
purpose of calculating is to make sure that design
saturation temperature is greater than 3 deg F .
Additionally, the calculation must verify that the fluid
freeze point is a minimum of 4 deg. F lower that the design
saturation temperature.The low evaporator temperature
cutout will be 4 deg F below the freeze point or -5 deg F ,
whichever is greater.
Important: When using glycol,Techview Setpoint View
setting for "Freeze Inhibitor Present" must
be set to "Yes" to prevent nuisance high
approach diagnostic.
Table 27, p.
53.
Table 27.
using the % glycol determined
Table
54?
28.
53