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COOL MODE DIAGNOSTIC HELP — To quickly deter-
mine the current trip points for the cooling modes, the Run
Status sub-menu at the local display allows the user to view the
calculated start and stop points for both the cooling and heating
trip points. The following sub-menu can be found at the local
display under
Run Status
→
TRIP
.
See Table 39.
Table 39 — Run Status Mode Trip Helper
The controlling temperature is “
TEMP
” and is in the middle
of the table for easy reference. The HVAC mode can also be
viewed at the bottom of the table.
SUMZ COOLING ALGORITHM — The SumZ cooling algo-
rithm is an adaptive PID (proportional, integral, derivative)
which is used by the control whenever more than 2 stages of
cooling are present (
C.TYP
= 1,2,3, and 5). This section will de-
scribe its operation and define the pertinent parameters. It is gen-
erally not necessary to modify parameters in this section. The
information is presented primarily for reference and may be
helpful for troubleshooting complex operational problems.
The only configuration parameter for the SumZ algorithm is
located at the local display under
Configuration
→
COOL
→
Z.GN
.
See Table 37
.
Capacity Threshold Adjust (
Z.GN
) — This configuration is
used on units using the “SumZ” algorithm for cooling capacity
control (
Configuration
→
UNIT
→
C.TYP
= 1, 2, 3 and 5). It
affects the cycling rate of the cooling stages by raising or
lowering the threshold that capacity must build to in order to
add or subtract a stage of cooling.
The cooling algorithm’s run-time variables are located at
the local display under
Run Status
→
COOL
.
See Table 40.
Current Running Capacity (
C.CAP
)
—
This variable repre-
sents the amount of capacity currently running in percent.
Current Cool Stage (
CUR.S
)
—
This variable represents the
cool stage currently running.
Requested Cool Stage (
REQ.S
)
—
This variable represents
the requested cool stage. Cooling relay timeguards in place
may prevent the requested cool stage from matching the cur-
rent cool stage.
Maximum Cool Stages (
MAX.S
)
—
This variable is the max-
imum number of cooling stages the control is configured for
and capable of controlling.
Active Demand Limit (
DEM.L
)
—
If demand limit is active,
this variable will represent the amount of capacity that the
control is currently limited to.
Capacity Load Factor (
SMZ
)
—
This factor builds up or
down over time (–100 to +100) and is used as the means of
adding or subtracting a cooling stage during run time. It is a
normalized representation of the relationship between “Sum”
and “Z”.
Next Stage EDT Decrease (
ADD.R
)
—
This variable repre-
sents (if adding a stage of cooling) how much the temperature
should drop in degrees depending on the
R.PCT
calculation
and exactly how much additional capacity is to be added.
ADD.R
=
R.PCT
*
(
C.CAP
— capacity after adding a cooling
stage)
For example: If
R.PCT
= 0.2 and the control would be
adding 20% cooling capacity by taking the next step up,
0.2 times 20 = 4 F (
ADD.R
)
Next Stage EDT Increase (
SUB.R
)
—
This variable repre-
sents (if subtracting a stage of cooling) how much the tempera-
ture should rise in degrees depending on the
R.PCT
calculation
and exactly how much capacity is to be subtracted.
SUB.R
=
R.PCT
*
(
C.CAP
— capacity after subtracting a
cooling stage)
For Example: If
R.PCT
= 0.2 and the control would be sub-
tracting 30% capacity by taking the next step down, 0.2 times
–30 = –6 F (
SUB.R
)
Rise Per Percent Capacity (
R.PCT
)
—
This is a real time cal-
culation that represents the amount of degrees of drop/rise
across the evaporator coil versus percent of current running
capacity.
R.PCT
= (
MAT
–
EDT
)/
C.CAP
Cap Deadband Subtracting (
Y.MIN
)
—
This is a
control vari-
able used for Low Temp Override (
L.TMP
) and Slow Change
Override (
SLOW
).
Y.MIN
=
-
SUB.R
*0.4375
Cap Deadband Adding (
Y.PLU
)
—
This is a control variable
used for High Temp Override (
H.TMP
) and Slow Change
Override (
SLOW
).
Y.PLU
=
-
ADD.R
*0.4375
Cap Threshold Subtracting (
Z.MIN
)
—
This parameter is
used in the calculation of
SMZ
and is calculated as follows:
Z.MIN
=
Configuration
→
COOL
→
Z.GN
* (–10 + (4*
(
–
SUB.R
))) * 0.6
Cap Threshold Adding (
Z.PLU
)
—
This parameter is used in
the calculation of
SMZ
and is calculated as follows:
Z.PLU
=
Configuration
→
COOL
→
Z.GN
* (10 + (4*
(
–
ADD.R
))) * 0.6
High Temp Cap Override (
H.TMP
)
—
If stages of mechani-
cal cooling are on and the error is greater than twice
Y.PLU
,
and the rate of change of error is greater than 0.5
°
F per minute,
then a stage of mechanical cooling will be added every 30 sec-
onds. This override is intended to react to situations where the
load rapidly increases.
Low Temp Cap Override (
L.TMP
)
—
If the error is less than
twice
Y.MIN
, and the rate of change of error is less than
–0.5
°
F per minute, then a mechanical stage will be removed
every 30 seconds. This override is intended to quickly react to
situations where the load is rapidly reduced.
Pull Down Cap Override (
PULL
)
—
If the error from set
point is above 4
°
F, and the rate of change is less than –1
°
F per
minute, then pulldown is in effect, and “SUM” is set to 0. This
keeps mechanical cooling stages from being added when the
error is very large, but there is no load in the space. Pulldown
for units is expected to rarely occur, but is included for the rare
situation when it is needed. Most likely pulldown will occur
when mechanical cooling first becomes available shortly after
the control goes into an occupied mode (after a warm unoccu-
pied mode).
Slow Change Cap Override (
SLOW
)
—
With a rooftop unit,
the design rise at 100% total unit capacity is generally around
30
°
F. For a unit with 4 stages, each stage represents about
7.5
°
F of change to EDT. If stages could reliably be cycled at
very fast rates, the set point could be maintained very precisely.
Since it is not desirable to cycle compressors more than 6 cy-
cles per hour, slow change override takes care of keeping the
PID under control when “relatively” close to set point.
ITEM
EXPANSION
UNITS
CCN
POINT
TRIP
MODE TRIP HELPER
UN.C.S
Unoccup. Cool Mode Start
dF
UCCLSTRT
UN.C.E
Unoccup. Cool Mode End
dF
UCCL_END
OC.C.S
Occupied Cool Mode Start
dF
OCCLSTRT
OC.C.E
Occupied Cool Mode End
dF
OCCL_END
TEMP
Ctl.Temp RAT,SPT or Zone
dF
CTRLTEMP
OC.H.E
Occupied Heat Mode End
dF
OCHT_END
OC.H.S
Occupied Heat Mode Start
dF
OCHTSTRT
UN.H.E
Unoccup. Heat Mode End
dF
UCHT_END
UN.H.S
Unoccup. Heat Mode Start
dF
UCHTSTRT
HVAC
the current HVAC MODE
String
Summary of Contents for WEATHERMASTER 48Z030
Page 103: ...103 Fig 15 Typical Power Schematic Sizes 030 050 Shown a48 8408 ...
Page 104: ...104 Fig 16 Main Base Board Input Output Connections a48 8409 ...
Page 105: ...105 Fig 17 RCB ECB CEM SCB Input Output Connections a48 8410 ...
Page 106: ...106 Fig 18 Typical Gas Heat Unit Control Wiring 48Z055 105 Units Shown a48 8411 ...
Page 107: ...107 Fig 19 Typical Electric Heat Unit Control Wiring 50Z055 105 Units Shown a50 8248 ...
Page 108: ...108 Fig 20 Typical Power Wiring 115 V 48Z Units a48 8412 ...
Page 109: ...109 Fig 21 Typical Power Wiring 115 V 50Z Units a50 8249 ...
Page 110: ...110 Fig 22 Typical Gas Heat Section Size 055 105 Units Shown a48 8413 ...
Page 111: ...111 Fig 23 Component Arrangement Size 030 050 Units ...
Page 112: ...112 Fig 24 Component Arrangement Size 055 070 Units ...
Page 113: ...113 Fig 25 Component Arrangement Size 075 105 Units ...