Maintenance - Trane Ice Bank Operation And Maintenance Manual

In a standard installation, ice is made at night. The water-
glycol solution circulates through the chiller and the Ice
®
Bank heat exchanger, bypassing the air handler coil. (See
Figure 2). The fluid temperature is about 25F (-3.9C) and
the water surrounding the heat exchanger freezes.
During the day, the glycol solution is cooled by the Ice
®
Bank tank from approximately 52ºF to 34ºF (11ºC to 1ºC).
(See Figure 3). A temperature modulating valve is used to
maintain a blended supply temperature typically 44ºF
(6.7ºC), by permitting sufficient 52F (11.1C) fluid to
®
bypass the Ice bank tank and mix with the 34F (1.1C)
fluid, to achieve the desired 44F (6.7C) temperature. The
44F (6.7C) fluid enters the coil, where it cools air
ordinarily from 75F to 55F (24C to 13C). The fluid leaves
the coil at 60F (15.6C), enters the chiller and is cooled to
52F (11.1C). In some systems, the ice will handle the
entire day time load (Full Storage) and in others, the ice
will help a smaller than full size chiller meet the load
(Partial Storage).

Maintenance

Since there are no moving parts in our standard thermal
storage tanks, the list of maintenance items is short. The
items we do list are important and should be done at
regular intervals as indicated. The inspection port cover
must always be replaced.
Water Level
The water level in the tank will rise and fall 2.5 to 7.8 inches
(63 to 195mm) (depending on Model No. of tank) during
the charge and discharge cycle. This change is due to
difference in the density of water and ice. Water expands
approximately 9% when changing to ice at 32ºF (0ºC);
therefore, during the freezing process, the level will rise.
(More about this in later sections). The water stays in the
tank (it is NOT pumped through the system) and the
amount of water/ice in the tank remains constant except
for possibly a slight amount of evaporation, which
normally occurs in outdoor, very hot, dry climates.
The water level should be just covering the top heat
exchanger tube, (which is 5/8 inch (16mm) diameter and
translucent) except for Model 1220, which is filled to the
bottom of the top HX tube. This measurement must be
done with no ice in the tank. The water level should be
checked every year except in hot, dry climates when every
three months is recommended.
Inventory Meter Calibration
During operation the only time to accurately check that the
the inventory meter probe level is correct is when the tank
is 100% charged. (See Ice Inventory Meter Manual IB-153
for more information.)
IB-SVX147D-EN
Coolant Concentration
The coolant should be checked regularly in accordance
with the manufacturer's recommendations. For ethylene
glycol mixtures, after the initial start up periods, a sample
should be sent once a year to the manufacturer for
analysis. Checking the coolant's freeze point is
recommended twice a year using a refractometer or
hydrometer, and not an automotive float-type device. The
maximum freezing point for our system is normally 
12ºF (-11.1ºC) (25%EG/H O); however, some jobs require
2
lower freeze points because of particular operating
conditions.
Storage Tank Water Treatment
Pour in the initial treatment of biocide into the tank water
upon filling. Generally, if tanks are kept at least partially
frozen year round, provide retreatment with biocide as
needed. However, if tanks are not kept frozen year round,
retreatment may be required more often and the tanks
should be checked for slime or odor seasonally. At the end
of the cooling season, you should fully charge the tanks
and leave them frozen until the start of your next air-
conditioning season. This will help to control biological
®
growth. CALMAC recommends a 20% Tetrakis
hydroxymethyl phosphonium sulfate solution such as
Aquacar PS20. All tank models require 16 oz. of biocide
solution per tank.
The CAS number is 555-66-30-8
Minimum shut off temperature
In most systems, the termination of the charge cycle is
determined by the temperature of the coolant leaving the
storage tanks. Typically this temperature is in the range of
27-28F (-2.7 to -2.2C). However, it is imperative that the
actual temperature be calculated for each system using
CALMAC Performance Data (IB-102).
This temperature is calculated by adding Coolant
Temperature Rise to the minimum Charging Coolant
Temperature. This temperature should be entered in the
first line of the maintenance record, (See
checked once every six months.
Ice Caps
The shut-off temperature previously discussed, is very
important. Setting the temperature lower than what is
stated in the Performance Data can cause the water in the
expansion area above the heat exchanger to freeze. It is
important that this water does not freeze so that it is
available to fill the voids created by the melting ice during
discharge. Therefore, twice a year the tank should be
checked for excessive ice-build-up above the top heat
exchanger tube. Ice thicker than 1 inch is an early
indication that the shut-off temperature is set too low.
Introduction
Table 1), and
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