271001-UIM-A-0407
Unitary Products Group
25
DIAGNOSTIC FAULT CODE STORAGE AND
RETRIEVAL
The control in this furnace is equipped with memory that will store up to
five error codes to allow a service technician to diagnose problems
more easily. This memory will be retained even if power to the furnace
is lost.
This feature should only be used by a qualified service tech-
nician.
The control stores up to five separate error codes. If more than five
error codes have occurred since the last reset, only the five most recent
will be retained. The furnace control board has a button, labeled "LAST
ERROR" that is used to retrieve error codes. This function will only work
if there are no active thermostat signals. So any call for heating, cooling
or continuous fan must be terminated before attempting to retrieve error
codes.
To retrieve the error codes, push the LAST ERROR button. The LED on
the control will then flash the error codes that are in memory, starting
with the most recent. There will be a two-second pause between each
flash code. After the error codes have all been displayed, the LED will
resume the normal slow green flash after a five second pause. To
repeat the series of error codes, push the button again.
If there are no error codes in memory, the LED will flash two green
flashes. To clear the memory, push the LAST ERROR button and hold it
for more than five seconds. The LED will flash three green flashes when
the memory has been cleared, then will resume the normal slow green
flash after a five-second pause.
FILTER PERFORMANCE
The airflow capacity data published in Table 16 represents blower per-
formance WITHOUT filters. To determine the approximate blower per-
formance of the system, apply the filter drop value for the filter being
used or select an appropriate value from Table 15.
NOTE:
The filter pressure drop values in Table 15 are typical values for
the type of filter listed and should only be used as a guideline. Actual
pressure drop ratings for each filter type vary between filter manufactur-
ers.
TABLE 15:
Filter Performance - Pressure Drop Inches W.C. and (kPa)
Airflow Range
Minimum
Opening Size
Filter Type
Disposable
Washable Fiber
Pleated
CFM
m
3
/min
in
2
cm
2
In W.C.
kPA
In W.C.
kPA
In W.C.
kPA
0 - 750
0 - 21.4
230
1484
0.01
0.00249
0.01
0.00249
0.15
0.03736
751 - 1000
21.25 - 28.32
330
2129
0.05
0.01245
0.05
0.01245
0.20
0.04982
1001 - 1250
28.33 - 35.40
330
2129
0.10
0.02491
0.10
0.02491
0.20
0.04982
1251 - 1500
35.41 - 42.48
330
2129
0.10
0.02491
0.10
0.02491
0.25
0.06227
1501 - 1750
42.49 - 49.55
380
2452
0.15
0.03736
0.14
0.03487
0.30
0.07473
1751 - 2000
49.56 - 56.63
380
2542
0.19
0.04733
0.18
0.04484
0.30
0.07473
2001 & Above
56.64 - Above
463
2987
0.19
0.04733
0.18
0.04484
0.30
0.07473
