Controls, Start-Up, Operation, Service and ... - Climayoreo

Table 36 — Cool/Heat Set Point Offsets Configuration
ITEM EXPANSION RANGE UNITS CCN POINT DEFAULT
D.LV.T COOL/HEAT SETPT. OFFSETS
L.H.ON Dmd Level Lo Heat On -1 - 2 ^F DMDLHON 1.5
H.H.ON Dmd Level(+) Hi Heat On 0.5 - 20.0 ^F DMDHHON 0.5
L.H.OF Dmd Level(-) Lo Heat Off 0.5 - 2.0 ^F DMDLHOFF 1
L.C.ON Dmd Level Lo Cool On -1 - 2 ^F DMDLCON 1.5
H.C.ON Dmd Level(+) Hi Cool On 0.5 - 20.0 ^F DMDHCON 0.5
L.C.OF Dmd Level(-) Lo Cool Off 0.5 - 2 ^F DMDLCOFF 1
C.T.LV Cool Trend Demand Level 0.1 - 5 ^F CTRENDLV 0.1
H.T.LV Heat Trend Demand Level 0.1 - 5 ^F HTRENDLV 0.1
C.T.TM Cool Trend Time 30 - 600 sec CTRENDTM 120
H.T.TM Heat Trend Time 30 - 600 sec HTRENDTM 120
Operating modes are under Operating ModesMODE.
ITEM EXPANSION RANGE CCN POINT
MODE MODES CONTROLLING UNIT
OCC Currently Occupied ON/OFF MODEOCCP
T.C.ST Temp.Compensated Start ON/OFF MODETCST
Cool Mode Evaluation Logic — The first thing the control
determines is whether the unit is in the occupied mode (OCC)
or is in the temperature compensated start mode (T.C.ST). If
the unit is occupied or in temperature compensated start mode,
the occupied cooling set point (OCSP) is used. For all other
modes, the unoccupied cooling set point (UCSP) is used. For
further discussion and simplification this will be referred to as
the “cooling set point.” See Fig. 6.
Demand Level Low Cool On Offset (L.C.ON) — This is the
cooling set point offset added to the cooling set point at which
point a Low Cool mode starts.
Demand Level High Cool On Offset (H.C.ON) — This is the
cooling set point offset added to the “cooling set point plus
L.C.ON” at which point a High Cool mode begins.
Demand Level Low Cool Off Offset (L.C.OF) — This is the
cooling set point offset subtracted from “cooling set point plus
L.C.ON” at which point a Low Cool mode ends.
NOTE: The “high cool end” trip point uses the “low cool off”
(L.C.OF) offset divided by 2.
To enter into a LOW COOL mode, the controlling temperature
must rise above [the cooling set point plus L.C.ON.]
To enter into a HIGH COOL mode, the controlling temperature
must rise above [the cooling set point plus L.C.ON plus
H.C.ON.]
To exit out of a LOW COOL mode, the controlling temperature
must fall below [the cooling set point plus L.C.ON minus
L.C.OF.]
To exit out of a HIGH COOL mode, the controlling temperature
must fall below [the cooling set point plus L.C.ON minus
L.C.OF/2.]
Comfort Trending — In addition to the set points and offsets
which determine the trip points for bringing on and bringing
off cool modes, there are 2 configurations which work to hold
off the transitioning from a low cool to a high cool mode if the
space is cooling down quickly enough. This technique is
referred to as comfort trending and the configurations of
interest are C.T.LV and C.T.TM.
Cool Trend Demand Level (C.T.LV) — This is the change in
demand that must occur within the time period specified by
C.T.TM in order to hold off a HIGH COOL mode regardless
of demand. This is not applicable to VAV control types
(C.TYP=1 and 2) in the occupied period. As long as a LOW
COOL mode is making progress in cooling the space, the control
will hold off on the HIGH COOL mode. This is especially
true for the space sensor machine control type (C.TYP) = 4,
because the unit may transition into the occupied mode and see
an immediate large cooling demand when the set points
change.
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Cool Trend Time (C.T.TM) — This is the time period upon
which the cool trend demand level (C.T.LV) operates and may
hold off staging or a HIGH COOL mode. This is not applicable
to VAV control types (C.TYP=1 and 2) in the occupied
period. See the Cool Trend Demand Level section for more
details.
Timeguards — In addition to the set points and offsets which
determine the trip points for bringing on and bringing off cool
modes there is a timeguard which enforces a time delay
between the transitioning from a low cool to a high cool mode.
This time delay is 8 minutes. There is a timeguard which
enforces a time delay between the transitioning from a heat
mode to a cool mode. This time delay is 5 minutes.
Supply Air Set Point Control — Once the control has determined
that a cooling mode is in effect, the cooling control
point (Run StatusVIEWCL.C.P) is calculated and is
based upon either SetpointsSA.HI or SetpointsSA.LO,
depending on whether a high or a low cooling mode is in
effect, respectively. In addition, if supply air reset is configured,
it will also be added to the cooling control point.
Refer to the SumZ Cooling Algorithm section for a discussion
of how the P Series ComfortLink controls manage
supply-air temperature and the staging of compressors for these
control types.
C.TYP = 3 (Thermostat Cool Mode Selection) — When a
thermostat type is selected, the decision making process involved
in determining the mode is straightforward. Upon energizing
the Y1 input only, the unit HVAC mode will be LOW
COOL. Upon the energizing of both Y1 and Y2 inputs, the unit
HVAC mode will be HIGH COOL. If just input G is energized
the unit HVAC mode will be VENT and the supply fan will
run.
Selecting the C.TYP = 3 (TSTAT – MULTI) control type
will cause the control to do the following:
• The control will read both the ConfigurationUNIT
SIZE and ConfigurationUNIT50.HZ configuration
parameters to determine the number of cooling
stages and the pattern for each stage.
• An HVAC mode equal to LOW COOL will cause the
unit to select the SetpointsSA.LO set point to control
to. An HVAC mode equal to HIGH COOL will cause the
unit to select the SetpointsSA.HI set point to control
to. Supply air reset (if configured) will be added to either
the low or high cool set point.
• The control will utilize the SumZ cooling algorithm and
control cooling to a supply air set point. See the section
for the SumZ Cooling Algorithm section for information
on controlling to a supply air set point and compressor
staging.
COOL MODE DIAGNOSTIC HELP — To quickly determine
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 StatusTRIP. See Table 37.