Troubleshooting; Steam Coil Performance Problems; Steam Failure Modes; Vfd Diagnostics - Carrier AERO 39MN Installation, Start-Up And Service Instructions Manual

BOTTOM VIEW (R5)
BOTTOM VIEW (R6)
2
Fig. 139 — Main Fan Replacement
(Frame Sizes R5 and R6)
CONTROL PANEL CLEANING — Use a soft damp cloth to
clean the control panel. Avoid harsh cleaners which could
scratch the display window.
BATTERY REPLACEMENT — A battery is only used in
assistant control panels that have the clock function available
and enabled. The battery keeps the clock operating in
memory during power interruptions. The expected life for the
battery is greater than ten years. To remove the battery, use a
coin to rotate the battery holder on the back of the control
panel. Replace the battery with type CR2032.

TROUBLESHOOTING

Steam Coil Performance Problems —
ty is normally not a problem with steam coils. Low capacity
can result from blocked or plugged air side surface, an air
bound coil, or a coil which is filled with condensate because
of a non-functioning steam trap. The Carrier steam coils with
the 1-in. OD outer tube have at least twice the condensate
loading capacity of a coil with
Water hammer can damage the coil and cause leaks. It is
typically caused by improper piping of the steam supply, al-
lowing condensate to enter the coil with the steam supply; or
by accumulation of condensate in the coil which can occur
with the coils operating at partial load without a vacuum
breaking device.
Problems with temperature control can occur when a ther-
mostatic controller or steam control valve is not functioning
properly. Temperature control problems will also occur when
the steam controls valve is oversized. Consider
arrangements for full range control.
Problems with "water logging" of the condensate tubes
can occur when a coil with over 6-ft tubes is selected at high
air velocities, low steam pressures (below 5 psig) and high
density fin spacing (9 fins per inch or more). This high densi-
ty fin spacing, while producing high levels of heating capaci-
ty, also promotes excessive condensate. Given the length of
the tubes and the low steam supply pressure, condensate can
build up faster than the drain system can carry it away. Con-
siderations should be given for using two coils in series for
this application.
a39-2923
3
a39-2924
Coil capaci-
5 / -in. OD outer tubes.
8
1 / to 2 / valve
3 3
Steam Failure Modes —
could take as little as a weekend to damage a coil, or much
longer.
Problems occur quickly in coils using low pressure steam
(<3 psig). Water hammer can develop inside the coil at the
header end because the steam has already condensed and the
low steam pressure does not adequately clear it from the coil.
This condensate re-boils and starts up water hammer inside
the tubes. The action of this type of water hammer, which
sounds like crackling inside the coil, is many tiny bubbles im-
pinging on the inner and outer tubes. One result is the inner
tube gets work hardened and eventually shatters. Another re-
sult is the eventual erosion of the outer tube causing pinhole
leaks.
Coils which are not properly vented will eventually load
up with noncondensable gases. Coil performance (tempera-
ture rise) drops off as the noncondensables act as insulation
inside the tubes.
The coils may also fill with condensate. The collapsing
steam causes a vacuum inside the coil when the supply valve
closes. The trapped condensate will then freeze causing the
tubes to rupture after it melts. The use of a vacuum breaker at
the condensate discharge will aid in relieving the vacuum in
the coil and promote condensate drainage.
Refer to Tables 38-40 for 39M troubleshooting informa-
tion.
Disconnect power and allow all rotating equipment to stop
before servicing unit. Physically secure all fans before
performing unit service. Failure to do so may result in
serious personal injury or death.
Water coil performance (when piped in parallel flow), will
be reduced by approximately 5% for each coil row on coils 2
rows deep and deeper. Coils should always be piped with the
water inlet on the leaving air side of the coil, regardless of
water connection vertical position.
VFD Diagnostics —
and reports them using:
• the green and red LEDs on the body of the drive (located
under the keypad)
• the status LED on the control panel
• the control panel display
• The Fault Word and Alarm Word parameters bits
(parameters 0305 to 0309)
The form of the display depends on the severity of the er-
ror. The user can specify the severity for many errors by di-
recting the drive to ignore the error situation, report the situa-
tion as an alarm, or report the situation as a fault.
FAULTS (RED LED LIT) — The VFD signals that it has
detected a severe error, or fault, by:
• enabling the red LED on the drive (LED is either steady
or flashing)
• setting an appropriate bit in a Fault Word parameter (0305
to 0307)
• overriding the control panel display with the display of a
fault code
• stopping the motor (if it was on)
• sets an appropriate bit in Fault Word parameter 0305 to
0307
The fault code on the control panel display is temporary.
Pressing the MENU, ENTER, UP button or DOWN buttons
removes the fault message. The message reappears after a
few seconds if the control panel is not touched and the fault is
still active.
157
The following failure modes
WARNING
The drive detects error situations