26
stalled in the piping mains to prevent such material from en-
tering units during normal operation.
During system filling, air venting from the unit is accom-
plished by the use of standard manual air vent or optional au-
tomatic air venting installed on the coil. Manual air vents are
basically Schrader valves. For air venting, depress the valve
until the air has vented the coil. When water begins to escape
through the valve, release the valve. Automatic air vents may
be unscrewed one turn counterclockwise to speed initial vent-
ing but should be screwed in for automatic venting after start-
up operation. See Fig. 37 and 38.
Fig. 37 — Manual Air Vent
Fig. 38 — Automatic Air Vent
Air System Balancing
All duct stubs, grilles, filters, and return-access panels must
be properly installed to establish actual system operating con-
ditions BEFORE beginning air balancing operations.
Each individual unit and the attached ductwork is a unique
system with its own operating characteristics. For this reason,
air balancing is normally done by balance specialists who are
familiar with all procedures required to properly establish air
distribution and fan-system operating conditions. These pro-
cedures should not be attempted by unqualified personnel.
Units with no ductwork have air volumes predetermined at
the factory by supply grille size and normally do not require
air balancing other than selecting the desired fan speed. Units
furnished with optional dampers on supply grilles may re-
quire some small adjustments to “fine tune” the air delivery
to each grille. Opposed blade balancing dampers are not
available for all grilles on a unit with electric heat.
After proper system operation is established, the actual unit air
delivery and the actual fan motor amperage draw for each unit
should be recorded in a convenient place for future reference.
Water System Balancing
A complete knowledge of the hydronic system, along with its
components and controls, is essential to proper water system
balancing. This procedure should not be attempted by unqual-
ified personnel. The system must be complete, and all com-
ponents must be in operating condition BEFORE beginning
water system balancing operations.
Each hydronic system has different operating characteristics
depending on the devices and controls used in the system.
The actual balancing technique may vary from one system to
another.
After the proper system operation is established, the appropri-
ate system operating conditions such as various water tem-
peratures and flow rates should be recorded in a convenient
place for future reference.
Before and during water system balancing, conditions may
exist due to incorrect system pressures which may result in
noticeable water noise or undesired valve operation. After the
entire system is balanced, these conditions will not exist on
properly designed systems.
Water Treatment
Proper water treatment is a specialized industry. Carrier rec-
ommends consulting an expert in this field to analyze the wa-
ter for compliance with the water quality parameters listed in
Table 2 and to specify the appropriate water treatment regi-
men. The expert may recommend typical additives such as
rust inhibitors, scaling preventative, antimicrobial growth
agents or algae preventatives. Anti-freeze solutions may be
used to lower the freezing point.
Carrier’s water coil tubes and headers are constructed of pure
copper. Multiple brass alloys may be present in the valve
package, depending on unit configuration. It is the user's re-
sponsibility to ensure the tube and piping materials furnished
by Carrier are compatible with the treated water.
Failure to provide proper water quality will void the fan coils
unit's warranty.
Table 2 — Water Quality Concentrations
Controls Operation
Before proper control operation can be verified, all other sys-
tems must be operating properly. The correct water and air
temperatures must be present for the control function being
tested. Some controls and features are designed to not operate
under certain conditions. For example, on a two-pipe cooling/
heating system with auxiliary electric heat, the electric heater
cannot be energized with hot water in the system.
A wide range of controls, electrical options and accessories
may be used with the equipment covered in this manual. Con-
sult the approved unit submittals, order acknowledgments,
and other literature for detailed information regarding each
individual unit and its controls. Since controls and features
may vary from one unit to another, care should be taken to
identify the controls used on each unit and their proper con-
trol sequence. Information provided by component manufac-
turers regarding installation, operation, and maintenance of
their individual controls is available upon request.
When changing from one mode to another (cooling to heating
or heating to cooling), it may take some time to actually no-
tice a change in the leaving air temperature. In addition, some
units may be designed for a very low air temperature rise in
heating. Before declaring a unit inoperative or a component
defective, it may be necessary to verify operation by more
than one method.
SERVICE
Excessive Condensation on Unit
Running chilled water through a fan coil unit with the unit fan
off can cause excessive condensation. If fan cycling is used, a
water flow control valve should be installed to shut off the
water when the fan stops.
Other methods of control that avoid condensation problems
are as follows:
1. Continuous fan operation with motorized chilled water
valve controlled by a thermostat.
2. Continuous fan operation with thermostat control to
switch fan from high to low speed (instead of off).
WATER CONTAINING REQUIRED CONCENTRATION
Sulphate Less than 200 ppm
pH 7.0 to 8.5
Chlorides Less than 200 ppm
Nitrate Less than 100 ppm
Iron Less than 4.5 mg/l
Ammonia Less than 2.0 mg/l
Manganese Less than 0.1 mg/l
Dissolved Solids Less than 1000 mg/l
CaCO
3
Hardness 300 to 500 ppm
CaCO
3
Alkalinity 300 to 500 ppm
Particulate Quantity Less than 10 ppm
Particulate Size 800 micron max
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