Solar System Design Guide
19
6020 457 - 01
Solar Control Unit SCU 124
Construction
The control unit comprises:
– PCB
– LCD
– Selector keys
– Connection terminals:
– 4x Sensor inputs
– 2x Relay outputs for actuating pumps and valves
– VBus connectivity
– Power supply (on-site ON/OFF switch)
– 2x Variable speed outputs for controlling the solar
circuit
pump
The standard delivery includes 1x collector temperature
sensor, 2x tank temperature sensors
Functions
■
3 basic system layouts
■
Switching the solar circuit pump for DHW and/or
swimming pool heating or space heating
■
Electronic limiter for the temperature in the DHW tank
(safety shutdown at 194°F (90°C)
■
Collector safety shutdown and collector cooling
■
Control of 1 storage tank/thermal load
■
Operating hour counter for relays
■
Energy metering
■
Thermostat function
■
Heat dump function
For further functions, see page 22.
– SCU 124
– 1x collector temperature sensor (FKP6)
– 2x tank temperature sensors (FRP6)
Collector temperature sensor (FKP6)
For connection inside the control.
On-site extension of the connecting lead:
– 2-core copper lead, cable length up to 197 ft. (60 m)
AWG 15-16 [cross-section of 0.00233 in
2
(1.5 mm
2
)]
– Never route this lead immediately next to 120/240V cables
Cable length
5 ft. (1.5 m)
Sensor type
PT1000
Permissible ambient temperature
– during operation
−
58 to 356°F
(
−
50 to +180°C)
– during storage and transport
−
4 to +158°F
(
−
20 to +70°C)
Delivered Condition
For systems with Viessmann DHW tanks, the tank
temperature sensor is installed in the solar brass elbow
located in the heating water return (see page 35).
Specifications
Rated voltage
100
−
240 VAC
Rated frequency
50
−
60 Hz
Rated current
4A
Power consumption
2W (in standby mode 0.7 W)
Safety category
II
Permissible ambient temperature:
– during operation
32 to 104°F
(0 to +40°C)
for use in the living space
or boiler room
– during storage and transport
−
4 to +150°F
(
−
20 to +65°C)
Rated relay output breaking capacity:
– Semi-conductor relay 1
1 A 100
−
240 VAC
– Semi-conductor relay 2
1 A 100
−
240 VAC
– Total
max. 2A
Tank temperature sensor (FRP6)
For connection inside the control.
On-site extension of the connecting lead:
– 2-core lead, cable length up to 197 ft. (60 m)
AWG 15-16 [cross-section of 0.00233 in
2
(1.5 mm
2
)]
– Never route this lead immediately next to 120/240V cables
Cable length
8.2 ft. (2.5 m)
Sensor type
PT1000
Permissible ambient temperature:
– during operation
23 to +176°F
(
−
5 to +80°C)
– during storage and transport
−
4 to +158°F
(
−
20 to +70°C)
Solar Control
