Nordic R-09, Инструкция по установке и обслуживанию

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11-May-2021 Page 34 002512MAN-01
OPERATION TROUBLESHOOTING - HEATING MODE
Fault Possible Cause Verification Recommended Action
High Discharge
Pressure
Low airflow See Fan Troubleshooting section Correct the problem.
TXV adjusted too far
closed
Verify superheat. It should be be-
tween 8-12°F (3-6°C). Superheat will
be high if TXV is closed too far.
Adjust TXV to obtain 8-12°F
(3-6°C) superheat.
TXV stuck almost closed
or partially blocked by for-
eign object
Adjusting the TXV does not affect the
superheat or the suction pressure.
Adjust the TXV all the way in and
out a few times to loosen it. Re-
place TXV if this does not work.
Filter-dryer plugged Feel each end of the filter- dryer; they
should be the same temperature. If
there is a temperature difference then
it is plugged. Also causes low suc-
tion pressure.
Replace filter-dryer.
Unit is overcharged
(Only possible if unit has
been field serviced and
incorrectly charged)
High subcooling, low delta T across
air coil.
Remove 1/2lb of refrigerant at a
time and verify that the discharge
pressure reduces. Or remove
charge and weigh back in the
amount listed on nameplate.
Low Suction
Pressure
Low or no outdoor liquid
flow
Delta T across the Outdoor Loop
ports should be 5-7°F (3-4°C), or
compare pressure drop to the tables
for the unit.
Determine the cause of the flow
restriction and correct it.
Verify pumps are working and
sized correctly for ground loop
systems.
Verify well pump and water valve
is working for ground water sys-
tems.
Entering liquid tempera-
ture too cold
Measure the entering liquid tempera-
ture to see if it is less than ~25F.
Increase the size of the ground
loop.
Dirty or fouled coaxial
heat exchanger (more
likely for open loop, un-
likely for ground loop)
Disconnect the water lines and check
the inside of the pipes for scale de-
posits.
Backflush the coaxial exchanger
with a calcium-removing cleaning
solution.
Return air too cold Measure return air temperature.
Should be above 60°F (15°C).
Restrict air flow temporarily until
room comes up to temperature.
TXV stuck almost closed
or partially blocked by for-
eign object
Adjusting the TXV does not affect the
superheat or the suction pressure.
TXV may be frosting up.
Adjust the TXV all the way in and
out a few times to loosen it. Re-
place TXV if this does not work.
Low refrigerant charge Entering liquid temperature, flow and
entering air temperature are good but
suction is low. Check static refrigera-
tion pressure of the unit for a very
low value. Weigh refrigerant out and
compare to charge listed on name-
plate.
Locate the leak and repair it.
Spray 9, a sniffer, and dye are
common methods of locating a
leak.
High Suction
Pressure
(may appear to
not be pumping)
Faulty compressor, not
pumping
Pressures change only slightly from
static values when compressor is
started.
Replace compressor.