Carrier 42NC, Installation, Operation And Maintenance Instructions, Page: 13 / 20

Water quality recommended for water coils:
It is recommended to carry out a bacteriological analysis
(detection of ferrobacteria, bacteria producing H2S and reducing
sulfates) and a chemical analysis (to avoid problems with scaling
and corrosion) of the water.
• Total hardness (French scale) 10 < TH < 15
• Chloride [CL-] < 10 mg/l
• Sulfate [SO
₄
2-] < 30 mg/l
• Nitrate [NO ₃ -] = 0 mg/l
• Dissolved iron < 0.5 mg/l
• Dissolved oxygen 4 < [O2] < 9 mg/l
• Carbon dioxide [CO2] < 30 mg/l
• Resistivity 2000 < Resistivity < 5000 Ωcm
• pH 6.9 < pH < 8
Operating limit recommendations:
Cooling coil inlet minimum water temperature: 5°C
Heating coil inlet maximum water temperature (2-pipe application
without electrical heater):
90°C
Heating coil inlet maximum water temperature (2-pipe application with
simultaneous electrical heaters):
55°C (min. air flow rate = 200 m³/h)
Heating coil inlet maximum water temperature (4-tube application):
90°C
Maximum operating pressure: 16 bar
Indoor return air min./max. temperature: +0°C/+40°C
Indoor return air maximum humidity level: 27°C DB (dry bulb) at 65%
RH (Relative Humidity).
Operating recommendation:
To prevent any inopportune opening of the thermo-actuators,
the temperature of the air surrounding the thermo-actuators
should be kept at no higher than 50°C. This risk must be taken
into account, especially for units in a confined space (
e.g. units
installed in a suspended ceiling).
CARRIER shall not be liable for damage to valves caused by
faulty design of the hydraulic supply network or incorrect
commissioning.
To protect against the risk of condensation when using chilled
water, lagging should be placed along the entire length of pipes
and the ends must be completely sealed. When using the water
coil and electric heater, we advise against using cross-linked
polyethylene (PEX) pipes to supply water to the unit. This is
because overheating of the electric heater could cause the
water temperature to rise briefly. This could cause the rapid
deterioration of the PEX pipe near the unit and cause it to burst.
We recommend using stainless steel braided (or equivalent)
hoses for hydraulic connections.
7 - CONDENSATE DRAIN PAN
The unit is equipped with a sloping polymer pan which does not
retain water, fitted with a Ø22 mm external drain end piece and
a plug.
When the unit is delivered, the pan is blocked on both sides (2
plugs), so it is therefore imperative that the plug is removed from
the side where the hydraulic connection is to be made.
If the hydraulic connection side is switched, do not
forget to refit the plug to the other side.
The connection can be made on the left or right-hand side of the
unit. The drain hose can be separate for each unit or corrected
to a main drain hose. Use a translucent and/or rigid drain pipe
with a minimum slope of 1 cm/m, with a constant
gradient along its whole length. Install a siphon trap measuring
at least 5 cm to prevent unpleasant gases or odours venting
from the drain.
An auxiliary pan must be installed on the connection side using
the 2 screws (fig.09a).
6 - HYDRAULIC CONNECTIONS
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