Fieldpiece HG2 - HVAC Guide System Analyzer - Manual (Page 21)

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5.401 Airfl ow OK: Th e indoor coil airfl ow was di-
rectly measured using the TrueFlow® grid and is
OK.
5.402 Probable OK airfl ow: Th e indoor coil air-
fl ow was tested by an indirect means (temperature
split) and is probably OK.
5.403 Airfl ow unknown, check airfl ow: Th e
measurements are insuffi cient to diagnose the in-
door coil airfl ow. Either measure the Return Ple-
num Dry Bulb, Wet Bulb and Supply Plenum Dry
Bulb or use a True Flow Plate.
5.404 Low airfl ow, increase airfl ow until actu-
al temp split matches target temp split: Th e
indoor coil airfl ow is low based on the temperature
split. Check the fi lter and coil, inspect for any re-
strictions and blockages. Make sure all registers are
open. If the airfl ow remains low, consider increased
blower speed and duct system modifi cations. Sup-
ply and return plenum static pressures can be used
to diagnose the causes of low airfl ow.
5.405 Low airfl ow, increase airfl ow: Th e indoor
coil airfl ow was directly measured using the True-
Flow grid and is low. Check the fi lter and coil, in-
spect for any restrictions and blockages. Make sure
all registers are open. If the airfl ow remains low,
consider increased blower speed and duct system
modifi cations. Supply and return plenum static
pressures can be used to diagnose the causes of low
airfl ow.
5.406 Low capacity or possible high airfl ow,
measure airfl ow directly: Th e temperature
split is low. Th is usually means that the capacity of
the system has been reduced due to incorrect refrig-
erant charge. Higher than expected airfl ow is rare,
but does occur occasionally. Measuring the airfl ow
directly would identify if high airfl ow is the cause of
the low temperature split.
The diagnosis are displayed in order
of likelihood.
Shows you where in this manual
you can get more information about
what the diagnosis means and how
to correct the problems.
5.3 CheckMe!® OUTPUT FORM Overview
Figure 21. CheckMe!® OUTPUT FORM.
Press the OUTPUT for the CheckMe!® OUTPUT
FORM.
Th e diagnoses and recommendations are listed in
order with the most likely diagnosis fi rst.
Because all parts of an A/C system are inter-depen-
dent, changes made to one part of the system can af-
fect other parts of the system. For example, increasing
airfl ow may increase the superheat, which may require
adding refrigerant. To be effi
cient, continually check the
superheat and/or subcooling as you make refrigerant
charge adjustments. Aft er fi nal modifi cations, allow 15
minutes to stabilize before your fi nal test.
5.4 Indoor Coil Airfl ow
Low airfl ow across the inside coil is one of the most
common problems and should be corrected before fi nal
decisions are made about refrigerant charge or many
other issues. Airfl ows in moist and wet climates should
usually be between 300 to 350 cfm per ton. Airfl ows in
Dry climates are limited by the rapidly increasing watt
draw of the fan motor at higher airfl ows.