Control Modes; Auto Adapt; Proportional-Pressure Mode; Constant-Pressure Mode - Johnson Controls SABROE WHC 2.1 Installation And Operating Manual

6. Control modes

6.1 AUTO
ADAPT
In AUTO mode, the pump is set to proportional-pressure
ADAPT
control. AUTO is recommended for two-pipe heating
ADAPT
systems. See section 6.6 Guide to control mode
AUTO selects the best control curve under the given
ADAPT
operating conditions, meaning that the pump performance is
automatically adjusted to the actual heat demand, that is the size
of the system and the changing heat demand over time, by
continuously selecting a proportional-pressure curve.
You cannot expect an optimum pump setting from day one. If the
power supply fails or is disconnected, the pump stores the
AUTO setting in an internal memory and resumes the
ADAPT
automatic adjustment when the power supply has been restored.
The pump is factory set to AUTO

6.2 Proportional-pressure mode

Proportional-pressure control adjusts the pump performance to
the actual heat demand in the system, but the pump performance
follows the selected performance curve, PP1, PP2 or PP3. See
fig. 15 where PP2 has been selected. The selection of the
proportional-pressure setting depends on the characteristics of
the heating system and the actual heat demand.
H
Fig. 15 Three proportional-pressure curves

6.3 Constant-pressure mode

The constant-pressure control adjusts the flow rate to the actual
heat demand in the system keeping a constant pressure at the
same time. The pump performance follows the selected
performance curve, CP1, CP2 or CP3. See fig.
been selected. The selection of the constant-pressure setting
depends on the characteristics of the heating system and the
actual heat demand.
H
Fig. 16 Three constant-pressure curves
12
selection.
.
ADAPT
PP3
PP2
PP1
Q
16 where CP1 has
CP3
CP2
CP1
Q

6.4 Constant curve/constant speed

At constant-curve/constant-speed operation, the pump runs at a
constant speed, independently of the actual flow rate demand in
the system. The pump performance follows the selected
performance curve, I, II or III. See fig.
selected. The selection of the constant-curve/constant-speed
setting depends on the characteristics of the heating system and
the number of taps likely to be opened at the same time.
H
Fig. 17 Three constant curve/constant speed settings

6.5 Automatic night setback

With automatic night setback enabled the pump automatically
changes between normal operation and the automatic night
setback curve.
The pump changes to automatic night setback when a flow-pipe
temperature drop of more than 10 to 15 °C within approximately
two hours is registered. The temperature drop must be at least
0.1 °C/min.
Changeover to normal operation takes place without a time lag
when the flow-pipe temperature has increased by approximately
10 °C. You do not have to re-enable automatic night setback if the
power supply has been switched off.
If the power supply is switched off when the pump is running on
the curve for automatic night setback, the pump starts in normal
operation. The pump changes back to the curve for automatic
night setback when the condition for automatic night setback is
fulfilled again.
If there is insufficient heat in the heating system, check whether
automatic night setback has been enabled. If yes, disable the
function.

6.6 Guide to control mode selection

System type
Recommended
Two-pipe
heating AUTO
ADAPT
system
One-pipe Constant
heating curve/constant
system speed, I, II or III
Underfloor Constant-pressure
heating curve, CP1, CP2 or
system CP3
Constant
Domestic hot
curve/constant
water system
speed, I, II or III
6.6.1 Changing from recommended to alternative pump
setting
Heating systems are relatively slow systems that cannot be set to
the optimum operation within minutes or hours.
If the recommended pump setting does not give the desired
distribution of heat in the rooms of the house, change the pump
setting to the shown alternative.
17 where II has been
Q
Pump setting
Alternative
Proportional-pressure
curve, PP1, PP2 or PP3
Constant-pressure curve
CP1, CP2 or CP3
Constant curve/constant
speed, I, II or III
Constant-pressure curve,
CP1, CP2 or CP3