Strebel S-WG 100, Installation, Operating And Maintenance Manual, Page: 40 / 125

E09.012.246 Manual S-WG
41
9.1.3
C
ONTROL GENERAL

There is no need for a sensor in the tank, because when the pump starts to run, the inlet sensor of the water
heater is measuring the water temperature of the tank.

When there is no drawing water from the tank, the inlet sensor is measuring the water temperature in the
tank.

After ending a heat demand, the pump has a post turning time.

On the control panel, the tank or hot water temperature can be set.

When a remote wall controller is connected to the wire terminal (13) and (14), the setting of the tank tem-
perature can be done with this controller (Open Therm bus), also the night or weekend reduction of tank
temperature.

During a period of no tapping, the temperature inside the tank is maintained at the Setting temperature
automatically.

A safety control stops the water heater from firing, when the temperature difference between flow and return
gets higher than allowed at the actual load (flow monitoring, ΔT function).

Parameters: the default of the parameters of the water heater control have been set for this type of tanks.
9.1.4
C
ASCADE CONTROL

Up to twelve water heaters can be cascaded.

One water heater has to be appointed master, the other water heaters are appointed slaves, each with
his own address in the software.

The slaves are connected with two wires to the master.

Every individual water heater has a connection for a pump.

An external temperature sensor is placed at the inlet tube of the system (S3), sensing the temperature of
the inlet water of the water heaters: the sensor has to be placed
close to the connection of the tank .

At a heat demand, the master water heater controls the heat output of the slaves, on base of the mea-
sured temperature of the external sensor.

When a slave stops burning, the pump connected to this slave has a post turning time.

When one water heater in the cascade installation is burning, the fans of the other water heaters are
turning at a low speed, preventing recirculation of the flue gases.

Flow monitoring cf. § 8.4 (page 37) remains active in every separate water heater of the cascade.