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

BOTTOM VIEW (R5)
BOTTOM VIEW (R6)
2
Fig. 192 — 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 ro-
tate the battery holder on the back of the control panel. Replace
the battery with type CR2032.

TROUBLESHOOTING

Steam Coil Performance Problems —
pacity is normally not a problem with steam coils. Low capaci-
ty 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 5 / -in. OD outer tubes.
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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 break-
ing 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 ve-
locities, low steam pressures (below 5 psig) and high density
fin spacing (9 fins per inch or more). This high density fin
spacing, while producing high levels of heating capacity, 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. Considerations
should be given for using two coils in series for this applica-
tion.
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 impinging
on the inner and outer tubes. One result is the inner tube gets
work hardened and eventually shatters. Another result is the
eventual erosion of the outer tube causing pinhole leaks.
Coils which are not properly vented will eventually load up
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with noncondensable gases. Coil performance (temperature
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 50 and 51 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 wa-
ter connection vertical position.
VFD Diagnostics —
Coil ca-
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 error.
The user can specify the severity for many errors by directing
the drive to ignore the error situation, report the situation as an
alarm, or report the situation as a fault.
FAULTS (RED LED LIT) — The VFD signals that it has de-
tected 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
1 / to 2 / valve
3 3
(0305 to 0307)
• overriding the control panel display with the display of a
fault code
• stopping the motor (if it was on)
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.
236
The following failure modes
WARNING
The drive detects error situations