Trane R Series Installation Operation & Maintenance page 31

Water Pressure Relief Valves
CAUTION
Shell Damage!
To prevent shell damage, install
pressure relief valves
evaporator water system.
Install a water pressure relief valve in
the evaporator inlet piping between
the evaporator and the inlet shutoff
valve, as shown. Water vessels with
close-coupled shutoff valves have a
high potential for hydrostatic pressure
buildup on a water
increase. Refer to applicable codes for
relief valve installation guidelines.
Freeze Protection
If the unit will remain operational at
subfreezing ambient
the chilled water system must be
protected from freezing. Heaters are
factory-installed on the packaged unit
evaporator and will help protect it from
freezing in ambient temperatures down
to -20°F (-29°C).
Install heat tape on all water piping,
pumps, water box nozzles 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.
Add a non-freezing, low temperature,
corrosion inhibiting, heat transfer fluid
may also be added to the chilled water
system. The solution must be strong
enough to provide protection against
ice formation at the lowest anticipated
ambient temperature. Refer to Table
in the General Information section for
evaporator water storage capacities.
NOTE: Use of glycol type antifreeze
reduces the cooling capacity of the unit
and must be considered in the design of
the system specifications.
RTAC-SVX002A-EN
Installation Mechanical
CAUTION
Evaporator Damage!
ALL unit chilled water pumps must
be controlled by the Trane CH530 to
avoid catastrophic damage to the
in the
evaporator due to freezing. Refer to
RLC-PRB012-EN.
Low Evaporator Refrigerant Cutout
and % Glycol Recommendations
1. Solution freeze point is 4 deg F below
operating point saturation temperature.
2. LRTC is 4 deg F below freeze point.
temperature
Procedure
1. Is operating condition contained
within Table? If no see "Special" below.
2. For leaving fluid temperatures greater
temperatures, than 40 deg F, use settings for 40 deg F.
3. Select operating conditions from
Table.
4. Read off recommended % glycol.
5. Go to Table from the % glycol.
Important
1. Additional
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.
2. If additional glycol is used, then use
the actual % glycol to establish the low
refrigerant cutout setpoint.
3. 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
The following constitute a special that
must be calculated by engineering:
1.
Ethylene Glycol or Propylene Glycol.
2.
4 to 16 deg F.
3.
Standard, Standard with extra pass, and
Premium.
4.
maximum in column in Table.
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.
glycol beyond the
Freeze inhibitor other than
Fluid delta T outside the range
Unit configuration other than
% Glycol greater than
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