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the end panel of the coil section. All
connections are labeled on the end panel.
For
control
equipment,
follow
recommendations from the manufacturer
regarding the types, sizing and installation
of equipment. Hot water coils are not
recommended to be used with entering air
below 40
o
F (4.4
o
C). Refer appendix 9.2 for
water quality.
5.6.3 Winterizing Water Coils
Coil freeze-up may occur due to air
stratification, failure of outdoor air
dampers and/or preheat controls. Routine
draining of water coils for winter shutdown
cannot guarantee zero freeze-up incidents,
which may result in coil damage. It is
recommended to completely drain the coil
and treated with anti-freeze solution.
Fill each coil independently with an anti-
freeze solution by using a small circulating
pump follow by complete draining. Check
the freezing point of anti-freeze before
proceed in each coil. Diluted effect
normally occurred due to a small amount
of water always remaining in each coil.
Therefore, ensure sufficient amount of
anti-freeze solution be remained in coil to
prevent freeze-up.
5.6.4 Direct Expansion Coils
For each coil, individual expansion devices
must be provided for header suction
connection. If the air flow through two or
more coils in parallel or stacked coil bank,
the suction piping must be installed in
such a way that refrigerant from one coil
suction header cannot reach another coil
suction header. The bulb for the control
valve must be attached to the header or
the coil or section of coil fed by valve and
not to a common header. When two or
more coils are connected to a common
suction line, never place the bulb on the
common line.
Thermostatic expansion valve is to be
equipped with external equalizer tubes
that are field connected to the suction line.
The valve should be in accordance to the
manufacturer recommendations, allowing
approximately 35-psi pressure drop
through the coil and distributor at full load.
Do not oversize the valve, proper
expansion valve operation is necessary in
order to realize the rated coil capacity.
IMPORTANT
CAREFULLY
READ
THROUGH
MANUFACTURING INSTRUCTION
FOR
APPLING
ANTI-FREEZE
SOLUTION.
SOME
PRODUCTS
WILL HAVE DIFFERENT FREEZING
POINT IN ITS NATURAL STATE
WHEN MIXED WITH WATER. COIL
FREEZE-UP
IS
NOT
THE
RESPONSIBILITY
OF
MANUFACTURER
It is not recommended to operate DX coil
for air-conditioning purpose at below
freezing suction temperature, 0
o
C which
will result frost build-up at fins surface. If
the full load operating point for the coil is
selected at a “safe” temperature, a system
analysis is required to check for the lowest
probable suction temperature at light load
condition.
5.6.5 Piping Diagram (VRV AHU)
For piping diagram of VRV AHU model,
please refer to the VRV ED or refer to
manufacturer for advices.
5.6.6 Drain Pan Trap
Drain pipes and traps must be at least
same diameter as the drain pan
connection. Drain pan must be level to
permit condensation from coil drain freely
for the recommended depth and distance
of drain trap installation. (See Figure 21)
Drain pan are not designed to be walked
on.
Figure 21 – Drain Trap Arrangement
5.7 Electrical Installation
Electric connecting should be compliant
with relevant local laws and regulations.
