Bryant SERIES D 453 - Manual (Page 8)

Corrosion Protection
The components of the chilled water circuit must be
protected from corrosion by the addition of an inhibitor
to the chilled water circuit. Chilled water additive
P/N 6463 ID 1 must be added to the chilled water circuit
when water only, or water and methanol antifreeze
are used in the chilled water circuit.
The chilled water additive package P/N 6463 ID 1
contains sufficient corrosion protection for chilled water
systems containing up to 10 gallons of water. For
systems larger than 10 gallons, add 1/2 package for
each additional 5 gallons of water or fraction thereof.
To estimate the chilled water capacity of the chilled
water circuit, refer to Table IV.
TABLE IV
Water Capacity
in Gallons
48-453 Chiller Tank 3.8
Bryant 18,000 Btuh coil 0.6
Bryant 48,000 Btuh coil 1.3
Bryant 36,000 Btuh coil 1.0
1 ft. 3/4-inch pipe 0.03
1 ft. l-inch pipe 0.05
Add required amount of the chilled water additive by
spreading additive over the distributor pan while water
is circulating (pump running).
CAUTION: Do not add any type of chilled water
additive when Ucar-17 antifreeze is used for freeze
protection. Ucar-17 contains sufficient inhibitor when
used in the recommended concentration listed in Tables
V and VI. Refer to following section on Freezing
Weather Protection.
Freezing Weather Protection
Model 48-453 was not designed for operation at out­
door ambients below 40°F.
Freeze protection is normally required only on those
systems which:
(a) Use hard piping (copper or galvanized).
(b) Use polyethylene piping without sufficient length
of piping in the conditioned space.
(c) Have the cooling coil in an unheated area where
freezing could occur, such as a rooftop unit.
Table V lists the type of antifreeze, minimum amount
of concentration, and the type of chilled water additive
to use in the chilled water system.
TABLE V
Antifreeze
*Minimum Concentration
(Percent of Volume)
Type of Chilled
Water Additive
Methanol 20 Borax & Chromate
(P/N 6463 ID 1)
Ucar-17 33 None-See Note 1
NOTE 1: Ucar-17 is the only approved permanent
(Glycol-base) antifreeze for use with galvanized
systems. Do not add any other chilled water additive
to systems containing Ucar-17. The system must be
thoroughly flushed before changing from another
chilled water additive or antifreeze to Ucar-17.
In any system containing both aluminum and galvanized
chillers, Ucar-17 must be used when freeze protection
is required and the minimum concentration must be
33% by volume. Do not use any other chilled water
additive.
TABLE VI
Lowest Outdoor Winter
Temperature ( F)
Percent of
Antifreeze Concentration
Menthanol Ucar-17
20 20 33
15 20 33
10 22 33
5 26 33
0 29 33
-5 32 36
- 10 34 39
- 15 36 42
-20 38 45
-25 43 47
-30 44 49
*For protection required at various ambients, refer to Table VI.
VI. CHECKING THE UNIT OPERATION
1. Be sure main manual gas valve is oif. Light pilot
as described on the unit rating plate.
2. Set thermostat to “cool”; set thermostat fan switch
to “auto”; set thermostat below-room temperature.
3. Turn on power at main disconnect switch to unit.
4. Check indoor fan operation by turning thermostat
fan switch to “on” for continuous operation. Move
thermostat above room temperature and observe that
the indoor fan remains on.
5. To place the system in operation; open the main
manual gas valve, replace all panels, and set the ther­
mostat at the desired temperature.
Control Circuit Operation
Refer to Figure 9. Note that 24 volts (transformer
secondary voltage) is applied to chiller terminals R and
F whenever 230V-60Hz-lc/) volt power is supplied to
the unit. When the thermostat calls for cooling, chiller
terminal R is connected to chiller terminal Y through
the thermostat.
Automatic Pilot Reignitlon
The automatic pilot reignition circuit consists of the
resistor (llA), pilot assembly (6B), and pilot pressure
switch (7P). The pilot pressure switch (7P) contacts
close when gas is turned on to the unit and current
flows through the resistor (11 A), glow coil of pilot
assembly (6B) via the pilot’s normally closed contacts.
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