Controls, Start-Up, Operation, Service and ... - Climayoreo
Controls, Start-Up, Operation, Service and ... - Climayoreo
Controls, Start-Up, Operation, Service and ... - Climayoreo
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Dem<strong>and</strong> Level Low Heat Off Offset (L.H.OF) — This is the<br />
heating set point offset above [the heating set point minus<br />
L.H.ON] at which point the Low Heat mode ends.<br />
To enter into a LOW HEAT mode, if the controlling temperature<br />
falls below [the heating set point minus L.H.ON], then<br />
HVAC mode = LOW HEAT.<br />
To enter into a HIGH HEAT mode, if the controlling temperature<br />
falls below [the heating set point minus L.H.ON minus<br />
H.H.ON], then HVAC mode = HIGH HEAT.<br />
To get out of a LOW HEAT mode, the controlling temperature<br />
must rise above [the heating set point minus L.H.ON plus<br />
L.H.OF].<br />
To get out of a HIGH HEAT mode, the controlling temperature<br />
must rise above [the heating set point minus L.H.ON plus<br />
L.H.OF/2].<br />
The Run Status table in the local display allows the user to<br />
see the exact trip points for both the heating <strong>and</strong> cooling modes<br />
without doing the calculations.<br />
Heat Trend Dem<strong>and</strong> Level (H.T.LV) — This is the change in<br />
dem<strong>and</strong> that must be seen within the time period specified by<br />
H.T.TM in order to hold off a HIGH HEAT mode regardless of<br />
dem<strong>and</strong>. This is not applicable to VAV control types (C.TYP=1<br />
<strong>and</strong> 2) in the occupied period. This technique has been referred<br />
to as “Comfort Trending.” As long as a LOW HEAT mode is<br />
making progress in warming the space, the control will hold off<br />
on a HIGH HEAT mode. This is relevant for the space sensor<br />
machine control types (C.TYP = 4) because the unit may transition<br />
into the occupied mode <strong>and</strong> see an immediate <strong>and</strong> large<br />
heating dem<strong>and</strong> when the set points change.<br />
Heat Trend Time (H.T.TM) — This is the time period upon<br />
which the heat trend dem<strong>and</strong> level (H.T.LV) operates <strong>and</strong> may<br />
work to hold off staging or a HIGH HEAT mode. This is not<br />
applicable to VAV control types (C.TYP=1 <strong>and</strong> 2) in the<br />
occupied period. See “Heat Trend Dem<strong>and</strong> Level” section for<br />
more details.<br />
HEAT MODE DIAGNOSTIC HELP — To quickly determine<br />
the current trip points for the low <strong>and</strong> high heat modes,<br />
there is a menu in the local display which lets the user quickly<br />
view the state of the system. This menu also contains the cool<br />
trip points as well. See Table 42 at the local display under Run<br />
StatusTRIP.<br />
The controlling temperature is “TEMP” <strong>and</strong> is in the middle<br />
of the table for easy reference. Also, the “HVAC” mode can be<br />
viewed at the bottom of the table.<br />
TWO-STAGE GAS AND ELECTRIC HEAT CONTROL<br />
(HT.CF = 1,2) — If the HVAC mode is LOW HEAT:<br />
• If electric heat is configured, then the control will request<br />
the supply fan ON<br />
• If gas heat is configured, then the IGC <strong>and</strong> IFO output<br />
controls the supply fan request<br />
• The control will turn on Heat Relay 1 (HS1)<br />
• If evaporator discharge temperature is less than 50 F,<br />
then the control will turn on Heat Relay 2 (HS2)*<br />
Table 41 — Heat/Cool Set Point Offsets<br />
59<br />
*The logic for this “low heat” override is that one stage of<br />
heating will not be able to raise the temperature of the supply<br />
airstream sufficient to heat the space.<br />
If the HVAC mode is HIGH HEAT:<br />
• If electric heat is configured, then the control will request<br />
the supply fan ON<br />
• If gas heat is configured, then the IGC <strong>and</strong> IFO output<br />
controls the supply fan request<br />
• The control will turn on Heat Relay 1 (HS1)<br />
• The control will turn on Heat Relay 2 (HS2)<br />
HYDRONIC HEATING CONTROL (HT.CF = 4) — Hydronic<br />
heating in P Series units refers to a hot water coil controlled<br />
by an actuator. This actuator is a communicating actuator<br />
<strong>and</strong> may be field supplied. When Configuration<br />
HEATHT.CF=4, there is a thermistor array called TemperaturesAIR.TCCT,<br />
that is connected to the RXB, that<br />
serves as the evaporator discharge temperature (EDT). The<br />
leaving-air temperature (LAT) is assigned the thermistor that is<br />
normally assigned to EDT <strong>and</strong> is located at the supply fan<br />
housing (TemperaturesAIR.TSAT).<br />
The configurations for hydronic heating are located at<br />
the local displays under ConfigurationHEATHH.CF.<br />
See Table 43.<br />
Hydronic Heating Control Proportional Gain (HW.P) — This<br />
configuration is the proportional term for the PID which runs in<br />
the HVAC mode LOW HEAT.<br />
Hydronic Heating Control Integral Gain (HW.I) — This<br />
configuration is the integral term for the PID which runs in the<br />
HVAC mode LOW HEAT.<br />
Hydronic Heating Control Derivative Gain (HW.D) — This<br />
configuration is the derivative term for the PID which runs in<br />
the HVAC mode LOW HEAT.<br />
Hydronic Heating Control Run Time Rate (HW.TM) —<br />
This configuration is the PID run time rate which runs in the<br />
HVAC mode LOW HEAT.<br />
Hydronic Heating Logic<br />
If the HVAC mode is LOW HEAT:<br />
• The control will comm<strong>and</strong> the supply fan on<br />
• The control will modulate the hot water coil actuator to<br />
the heating control point (Run StatusVIEW<br />
HT.C.P). The heating control point for hydronic heat is<br />
the heating supply air set point (SetpointsSA.HT).<br />
If the HVAC mode is HIGH HEAT:<br />
• The control will comm<strong>and</strong> the supply fan on<br />
• The control will comm<strong>and</strong> the hot water coil actuator to<br />
100%.<br />
Hydronic Heating PID Process — If the HVAC mode is<br />
LOW HEAT, then the hydronic heating actuator will modulate<br />
to the heating control point (Run StatusVIEWHT.C.P).<br />
Control is performed with a generic PID loop where:<br />
Error = Heating Control Point (HT.C.P) – Leaving Air Temperature<br />
(LAT)<br />
ITEM EXPANSION RANGE UNITS CCN POINT DEFAULT<br />
D.LV.T COOL/HEAT SETPT. OFFSETS<br />
L.H.ON Dmd Level Lo Heat On -1 - 2 ^F DMDLHON 1.5<br />
H.H.ON Dmd Level(+) Hi Heat On 0.5 - 2.0 ^F DMDHHON 0.5<br />
L.H.OF Dmd Level(-) Lo Heat Off 0.5 - 2 ^F DMDLHOFF 1<br />
L.C.ON Dmd Level Lo Cool On -1 - 2 ^F DMDLCON 1.5<br />
H.C.ON Dmd Level(+) Hi Cool On 0.5 - 2 ^F DMDHCON 0.5<br />
L.C.OF Dmd Level(-) Lo Cool Off 0.5 - 2 ^F DMDLCOFF 1<br />
C.T.LV Cool Trend Dem<strong>and</strong> Level 0.1 - 5 ^F CTRENDLV 0.1<br />
H.T.LV Heat Trend Dem<strong>and</strong> Level 0.1 - 5 ^F HTRENDLV 0.1<br />
C.T.TM Cool Trend Time 30 - 600 sec CTRENDTM 120<br />
H.T.TM Heat Trend Time 30 - 600 sec HTRENDTM 120