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16 - CONTROLS
Exemple : Two-stage water heater for a water temperature range of 35 40°C.
Parameter settings: STP = 40°C, SD = 2 K, ISD = 1.5 K.
On
38
R E T U R N
S E T P O I N T
16.3.2 - Water supply control (P141 = 2)
If heating mode is selected with a water-to-water unit, the setpoint is adjusted based on the temperature measured by the hot water
supply sensor. If cooling mode is selected and P6 = 1, the setpoint is adjusted based on the temperature measured by the heat
exchanger outlet sensor. If P6 = 2 in the same mode, it is adjusted based on the temperature measured by the manifold sensor.
The type of control used is PIDτ.
The temperature is measured periodically (τ) then compared to the setpoint and multiplied by a proportional coefficient (P) -- taking
into account the difference between the measurement and the setpoint (D) and the change in the difference between the measurement
and the setpoint (I) -- in order to approach the setpoint quickly.
Formula: EC = P (M-C) t1 + ∫(M-C)*I + [(M-C) t0 - (M-C) t1]*D
M = Measurement, S = Setpoint.
When P146 = 0 and P147 = 0 (standard setting), the PIDτ function becomes PT (the Integral and Derivative functions are disabled).
■ The related parameters are as follows :
P251: Calculated setpoint
P121: Setpoint 1 in cooling mode
P123: Setpoint 1 in heating mode
P145: P coefficient
P146: I coefficient
P147: D coefficient
P148: T coefficient
► In cooling mode :
A call is made for an additional stage if:
DV > +1.0 K for the first stage and +0.5 K for the additional stages.
A call is made to turn off a stage if:
DV < –0.5 K for a stage and –1.0 K for the last stage.
Example: Two-stage unit with a 5°C setpoint, where D = 0 and I = 0.
P
0,5
1
1,5
2
► In heating mode :
A call is made for an additional stage if:
DV < –1.0 K for the first stage and -0.5 K for the additional stages.
A call is made to turn off a stage if:
DV > +0.5 K for a stage and +1.0 K for the last stage.
84
Stage 1
Off
40
Stage 2
35
36
36,5
37
T E M P . : - x x . x °
Stage 1
Off
3
4
4,33
4,5
On
36,5
Stage 1
38
38,5
39
40
Csg
: - x x . x °
Stage 2
4
4,5
4,66
4,75
Stage 2
Off
38,5
Water inlet temp.
Stage 1
On
6
5,5
5,33
5,25
7
6
5,66
5,5
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