12
Cascade switching
The FRISTAR3 is designed for a maximum water draw-off of 30 l/min. For a greater draw-off of do
-
mestic hot water, multiple freshwater stations can be used in a cascade.
The first module is fed directly, all others stations are added with stop valves, if necessary. These
valves must open or close in at least 30 seconds. The
UDV
universal 3-way valve from Technische
Alternative is excellent for this purpose.
Valves are added via overriding controller with a volume flow sensor that measures the total volume
flow. With up to 3 modules, the FTS5-85DL sensor is adequate; with 4-5 modules, the FTS9-150DL
sensor must be used.
The sensors in the FRISTAR stations should not be subjected to more than 30 litres per minute. The
final station, however, should be flushed several times a day to prevent stagnant water from forming.
This is ensured if the overriding controller increases the station number in stages of about 8-10 l/
min. In the following "step-by-step" instructions, the first stage with 9 l/min was selected because
sensor FTS9-150DL is activated properly starting at 9 l/min only.
A UVR67 controller can be used for switching the modules. Cascade control can of course also be
integrated into the programs of freely programmable controllers.
Hydraulic circuit diagram of a cascade with four FRISTAR3 fresh
water stations
Figure with fresh water stations version, version "Pump on the right"
The initial designations for stop valves
A1 – A3
refer to controller UVR67.
