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Summary of Contents for Viessmann SCU 123
- Page 1 SCU 123 Solar control unit for the Solar-Divicon-HX Connection Operation and function Commissioning and adjustment Troubleshooting en-US/CA Thank you for buying this product. Read this manual carefully to get the best perfomance from this unit. Manual Please keep this manual carefully.
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Page 2: Table Of Contents
SCU 123 Contents 5 Channel overview ..........10 1 General ..............2 Display channels ............ 10 2 Overview and technical data ......3 Adjustment channels ..........12 System description ..........4 Electrical connection..........16 3 Operation and function ........6 Data communication / Bus ......... 17 Push buttons .............6... -
Page 3: Overview And Technical Data
SCU 123 Overview and technical data • System-monitoring-display • 4 Pt1000 temperature sensors • 2 semiconductor relays for pump speed control • Energy metering • VBus ® • User-friendly operation Technical data Housing: plastic, PC-ABS and PMMA Inputs: for 4 Pt1000 temperature sensors... -
Page 4: System Description
(P2) primary loop pump secondary loop pump The SCU 123 controller is used in solar thermal systems is switched on. If the temperature difference falls below the using the Solar-Divicon-HX with an external heat exchanger switch-off difference, the pump is switched off. - Page 5 SCU 123 Adjustment channels Channel Factory setting Change to Description Page DT1O 12 °Ra Switch-on temperature - primary loop DT2O 12 °Ra Switch-on temperature - secondary loop 8 °Ra Switch-off temperature - secondary loop 140 °F Target temperature 2 min...
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Page 6: Operation And Function
SCU 123 Operation and function The controller is operated via three push buttons below the display. Push buttons Button 1 is used for scrolling forward through the indication menu or to increase the adjustment values. Button 2 is used for scrolling backward and reducing values. Button 3 is used for selecting channels and confirming adjustments. -
Page 7: Flashing Codes
SCU 123 Flashing codes System screen flashing codes • Pumps are flashing when the corresponding relay is switched • Sensor symbols are flashing if the corresponding sensor display channel is selected • Sensors are flashing quickly in the case of a sensor fault •... -
Page 8: Commissioning
Î Enter the channel by pressing button 3 Î The symbol flashes. The three push buttons of the SCU 123 controller Î Adjust the value by pressing buttons 1 and 2 Î Save the adjustment by pressing button 3 again Î... - Page 9 SCU 123 8. Target temperature Î Adjust the target temperature Completing the commissioning menu After the last channel of the commissioning menu has been adjusted and confirmed, the controller asks for confirmation of the adjustments. Î To confirm the adjustments made in the commissioning...
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Page 10: Channel Overview
SCU 123 Channel overview Display channels Note: The displayed values and adjustment channels depend on the options and functions that have been selected. Only values and adjustment chan- nels available for the individual settings selected will appear in the menu. - Page 11 SCU 123 Operating hours counter The operating hours counter accumulates the operating hours of the respective relay (h P1, h P2). Full hours are h P1, h P2 : displayed. Operating hours counter The accumulated operating hours can be set back to zero.
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Page 12: Adjustment Channels
SCU 123 Adjustment channels ∆T -regulation The controller works as a standard differential controller. It calculates the temperature difference between the collec- DT1O / DT2O : tor sensor S1 and the upper DHW store sensor S3. If this Switch-on temperature diff. - Page 13 SCU 123 Maximum tank temperature Once the adjusted maximum temperature is exceeded, the solar pump is switched off and further loading of the S MX: tank is prevented to reduce scald risk or system damage. A Maximum tank temp. fixed hysteresis of 4 °Ra [2 K] is set for the maximum tank Adjustment range: temperature.
- Page 14 SCU 123 Heat exchanger temperature limitation The primary loop heat exchanger temperature limitation is set to 212°F [100°C] to protect the system against over- heating. Heat exchanger antifreeze function The antifreeze function of the heat exchanger activates R2 (100%) if the heat exchanger temperature falls below 40°F [5°C].
- Page 15 SCU 123 Energy metering If OHQM is activated, the heat quantity gained can be calcu- lated and displayed. Energy metering is possible if a flowme- OHQM: ter is used. To enable energy metering, proceed as follows: Energy metering Î Read the flow rate (gal/min) from the flowmeter at ma-...
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Page 16: Electrical Connection
SCU 123 Electrical connection The controller is mostly prewired in the factory. Sensors The station is connected to the power supply (100 ... 240 V~) S1 (collector temperature) and S3 (upper tank) must be with the already mounted connection cable. Works on cur- connected on site. -
Page 17: Data Communication / Bus
SCU 123 Data communication / Bus The controller is equipped with a VBus for data transfer ® with and energy supply to external modules. The connec- tion is carried out at the terminals marked “VBus” (either polarity). One or more VBus modules can be connected ®... -
Page 18: Troubleshooting
SCU 123 Troubleshooting fuse In the case of an error, a message is shown on the display of the controller: Warning symbols Operating control lamp VBus ® terminals sensor terminals ground load terminals terminals power supply terminals Operating control lamp off. -
Page 19: Various
SCU 123 Various: Pump is overheated, but no heat transfer from the Pump starts for a short moment, switches off, switches collector to the tank, flow and return have the same tem- on again, etc. perature; perhaps also air / gas bubbles in the lines. - Page 20 SCU 123 Tanks cool down at night Control the non-return Further pumps which are valve in warm water cir- connected to the solar culation - o.k. tank must also be che- cked. Collector circuit pump runs during the night? Check controller:...
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Page 21: Accessories
SCU 123 Accessories Smart Display SD3 The Smart Display is designed for simple connection to controllers with VBus . It is used for visualizing data issued ® by the controller: collector temperature, storage tempera- ture and energy yield of the solar thermal system. The use... - Page 22 As faults can never be excluded, please note: Your own calculations and plans, under con sider- approval of Viessmann Manufacturing Company Inc.. This ation of the current standards should only be basis for your especially applies for copies, translations, microfilms and the projects.
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