5.Control system - Meibes

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5. Control system 1) Based on the physical fact that the existing heat energy in the heat transfer unit has to be controlled by the control system, short-term temperature fluctuations at the start of a hot water tapping cannot be ruled out completely. Favourable control behaviour is achieved with the water temperature – cold function, which results in very short or no reheating time! 2) The plate heat exchanger is kept hot by the heat exchange media from the buffer. The heat exchange media can take on temperatures of more than 60°C. Please note that such temperatures can result in calcium oxide precipitation! 5.3.4 Manual operation menu ■ The output 1, output 2, output 3 and outputs „overall test” can be switched on and off manually, in order to check the functioning of the pumps. ■ Characteristic curve calibration Here the regulation of the characteristic curve is determined during the initial operation. (See 6.3.2) ■ Circulation adjustment In this menu item the circulation adjustment is carried out.(See 6.3.3) 5.3.5 Basic setting menu This menu contains important technical information and parameters for controlling, which may be modified by a specialist tradesman. In order to modify values, the submenu “release” in the basic setting menu has to be activated. (See 8) ■ Informationen Here information regarding the software and system version is given. ■ Controller ON/OFF 3) Amongst other things, this menu item contains the safety shutdown for a domestic hot water temperature of 60°C. Should this temperature be exceeded at T1, pump P1 switches off until the temperature drops to below 60°C. This value should be increased when the hot water – set value is increased. However, a blending valve should additionally be mounted on the domestic hot water outlet of the freshwater station. The other control parameters should not be adjusted! ■ Pulse generator 2) These values are used to adapt the flow rate generator at the control system. ■ Characteristic curve 2) In this menu item the pre-determined operating points of the control system can be read. In this menu item the pre-determined operating points of the control system can be read. Likewise the default value for flow max. of the characteristic curve calibration can be modified. Should, for example, the 25l/mm for the characteristic curve at flow max. not be reached, the default value for flow max. can be lowered to 15l/mm. (See 6.3.2) ■ Heat transfer unit After run 2) Outside the circulation time and after a drawing off of hot water, it is possible to keep the circulation pump running afterwards. The stainless steel plate heat exchanger is cooled down and its decalcification is counteracted. The function of the after-run, from an energy point of view, is only meaningful and possible outside the circulation time! ■ Circulation ON/OFF If this function has been activated, up to three time slots can be set in the „programming” menu. In the time slot, controlling is always based on the circulation temperature. If the time slot has ended, or drawing off takes place or the circulation temperature has been reached, the circulation switches off. It is attached to the circulation rest time. No circulation can be activated in the circulation rest time. To avoid the heat transfer media in the buffer from being mixed, the heat transfer media temperature is checked at the heat transfer media- flow- sensor T2 or with the option at T5 at the start of the circulation process, to ensure that the heat transfer media temperature is greater than the circulation set temperature +2K. This happens at T2 with the following procedure: The heat transfer pump P1 runs for 5 minutes at minimal capacity. Should the circulation set temperature plus 2K not be attained after expiry of the 5 minute run time, the heat transfer pump P1 is switched off – and restarts the process again after a waiting period of one hour. Following this, the flashing message „error message flow temperature” will be seen on the display in the information menu. Flow increase 5 K In some cases (high temperature drops in circulation capacity), the circulation return temperature is not reached. The set value of the circulation temperature (flow increase 5K) can be increased up to 20 K. The input is limited to the hot water set temperature value. Should the hot water set temperature be reduced, the flow increase value for circulation is also reduced! Example: Circulation set = 35°C, hot water set = 50°C, flow Increase = 15 K possible Circulation set = 40°C, hot water set = 50°C, flow Increase = 10 K possible Circulation set = 40°C, hot water set = 45°C, flow Increase = 5 K possible 9
5. Control system If a buffer sensor T5 is available as an option for the activation of the reheating function and its temperature is less than the circulation temperature + 2K, the circulation is then discontinued. As a result of the reheating function it is to be assumed that after reheating and for a conceivable period of time thereafter sufficient temperature is available in the buffer. Outside the active time slot, the circulation is always in the “pulse generated” mode, i.e. always when a drawing off of approx. 1 s has been carried out, the circulation pump is switched on for the programmed time in “circulation-running time” and the circulation is then also blocked from being reactivated for the preset “circulation-rest time” period. Circulation running time = 300 s From 0 – 600 s adjustable running time of the circulation pump. Circulation rest time = 5 min From 0 – 120 min adjustable blocking time for reactivating the circulation. Circulation hot water set value = 40°C From 10°C to 50°C adjustable temperature for circulation in the time slot. Sensor TF3 = select sensor T3 or T6 (optional) In the factory setting T3 is used for measuring the circulation temperature. However, an independent sensor T6 (optional) can also be used directly in the circulation pipes for this purpose. Option T5: With an additional sensor T5 (optional), which is installed in the buffer, two further functions can be activated. ■ Activation T5 If the activation T5 = on is selected, it is possible to only put the control system into operation after a specified buffer temperature has been attained. Factory setting = off Switch-on temperature = 35°C temperature (adjustment range 35°C to 55°C) Hysteresis = 3 K (adjustment range 3 K to 10 K) ■ Reheating ON/OFF Optionally the additional „reheating” function can be activated. When there is a deviation lower than an adjustable set value for the buffer, this function is an external heat source which is activated to reheat the buffer until it reaches the set level. The requirement for this is that the heat source is actually able to supply the desired temperature level. For this purpose the contact S1 on the controller circuit board is used. This contact can be charged with 4 A 230 V AC. The set value for the storage temperature can be defined as an absolute value (fixed value e.g.: 65°C) or as a relative value. 10 Should the relative value be used, the set value for the buffer temperature is calculated from the programmed hot water – set temperature + the entered value for the „splay”. e.g.: hot water set temperature 50°C + splay 20 K = 70°C buffer temperature. Should the programmed or calculated set value deviate lower by 3 K, the external heat source is kept activated until the set value is reached again. The temperature values needed for this can be set in the programming menu, under the submenu “reheating”. (See 5.3.3) ■ Pre-mixer ON/OFF As a rule, this selection is not active in this control system! ■ Disinfection The “disinfection” function can be activated in the basic setting menu, but only if there is a circulation pipe available. The circulation return temperature is controlled, which is measured at the cold water sensor. This temperature must be attained for the preset disinfection time period. Short-term lower temperature deviations are corrected. In total, the actual time that the set temperature was attained, is counted. Should the flow temperature for the control system not be achieved, a corresponding error message is sent to the information menu after 30 minutes. During the disinfection of the hot water and circulation pipes, very high temperatures are achieved. There is therefore a danger of scalding! Qualified personnel should take the necessary precautions for the protection of persons and property! ■ Factory setting ON/OFF Should the controller be set back to the original factory positions as on delivery, this menu item is to be activated. ■ Release In order to „unlock“ the controller for different settings, the following should be done: Release by pressing the right key twice and “OFF” will flash. Press UP and DOWN and right key simultaneously for approx. 2s and release changes to „ON“. To subsequently leave the setting, press the left key. The same operating sequence is used to block access to the controller. Alternatively, this takes place automatically after 60 minutes. 2) This is executable within one minute after mains connection or by using the key combination. Access is automatically blocked after 60 minutes. 3) Only possible to activate „release” by using the key combination in the menu. Access is automatically blocked after 60 minutes.
Page 1 and 2: Technical information for installat
Page 3 and 4: 1. Safety instructions ■ The inst
Page 5 and 6: 3. Equipment and functional descrip
Page 7 and 8: 5. Control system 5.1 Display descr
Page 9: 5. Control system 5.3.1 Explanation
Page 13 and 14: 6. Initial operation and system cal
Page 15 and 16: 7. System examples 7.1 Freshwater s
Page 17 and 18: 7. System examples 7.6 Freshwater s
Page 19 and 20: 9. Trouble-shooting The following i
Page 21 and 22: 11. Diagrams Pressure loss [bar] 20

5.Control system - Meibes

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