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Mitsubishi Electric EHST20C-VM6HB Service Manual
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Mitsubishi Electric EHST20C-VM6HB Service Manual

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CYLINDER UNIT

SERVICE MANUAL

R410A
[Model name]
EHST20C-VM6HB
EHST20C-YM9HB
EHST20C-VM6B
EHST20C-YM9B
EHST20C-VM6EB
EHST20C-YM9EB
EHST20C-VM6SB
EHPT20X-VM2HB
EHPT20X-VM6HB
EHPT20X-YM9HB
EHPT20X-VM6B
EHPT20X-YM9B
CYLINDER UNIT
[Service Ref.]
EHST20C-VM6HB.UK
EHST20C-YM9HB.UK
EHST20C-VM6B.UK
EHST20C-YM9B.UK
EHST20C-VM6EB.UK
EHST20C-YM9EB.UK
EHST20C-VM6SB.UK
EHPT20X-VM2HB.UK
EHPT20X-VM6HB.UK
EHPT20X-YM9HB.UK
EHPT20X-VM6B.UK
EHPT20X-YM9B.UK
MAIN CONTROLLER
Note:
• This manual describes only
service data of cylinder unit.
• RoHS compliant products have
<G> mark on the spec name
plate.
CONTENTS
1. REFERENCE MANUAL ................................... 2
2. SAFETY PRECAUTION ................................... 3
3. SPECIFICATIONS ............................................ 6
4. PART NAMES AND FUNCTIONS .................. 7
5. OUTLINES AND DIMENSIONS ..................... 10
6. WIRING DIAGRAM ......................................... 11
7. FIELD WIRING ............................................... 24
8. WATER SYSTEM DIAGRAM ......................... 28
9. CONTROLS ................................................... 33
10. TROUBLESHOOTING ................................... 53
11. DISASSEMBLY PROCEDURE ...................... 69
13. SERVICE AND MAINTENANCE ................... 86
PARTS CATALOG (OCB531)
September 2012
No. OCH531

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Summary of Contents for Mitsubishi Electric EHST20C-VM6HB

  • Page 1: Service Manual

    CYLINDER UNIT September 2012 No. OCH531 SERVICE MANUAL R410A [Model name] [Service Ref.] Note: • This manual describes only EHST20C-VM6HB.UK EHST20C-VM6HB service data of cylinder unit. • RoHS compliant products have EHST20C-YM9HB.UK EHST20C-YM9HB <G> mark on the spec name EHST20C-VM6B.UK plate.

  • Page 2: Reference Manual

    REFERENCE MANUAL OUTDOOR UNIT'S SERVICE MANUAL Service Ref. Service Manual No. PUHZ-RP5/50/60/71VHA4 PUHZ-RP100/15/140VKA OCH451 PUHZ-RP100/15/140YKA PUHZ-HRP71/100VHA PUHZ-HRP71/100VHA PUHZ-HRP71/100VHAR1 PUHZ-HRP100VHAR OCH45 PUHZ-HRP100/15YHA PUHZ-HRP100/15YHA PUHZ-HRP100/15YHAR1 PUHZ-W50/85VHA(-BS) PUHZ-W50/85VHAR1(-BS) OCH49 PUHZ-W50VHAR(-BS) PUHZ-W85VHA.UK OCH465 PUHZ-W85VHA-BS.UK PUHZ-HW11/140YHA(-BS) PUHZ-HW11/140YHA(-BS) PUHZ-HW11/140YHAR1(-BS) PUHZ-HW11/140YHAR(-BS) PUHZ-HW140VHA(-BS) OCH49 PUHZ-HW140VHA(-BS) PUHZ-HW140VHAR1(-BS) PUHZ-HW140VHAR-BS PUHZ-HW140VHAR(-BS) PUHZ-SW40/45VHA(-BS) OCH55 PUHZ-SW75/100/10VHA(-BS)

  • Page 3: Safety Precaution

    Do not position furniture or electrical appliances below the outdoor unit or cylinder unit. The discharge pipework from the emergency devices of the cylinder unit should be installed according to local law. Only use accessories and replacement parts authorised by Mitsubishi Electric ask a qualified technician to fit the parts. Electrical All electrical work should be performed by a qualified technician according to local regulations and the instructions given in this manual.
  • Page 4 WARNING (SPLIT MODELS ONLY) Do not discharge refrigerant into the atmosphere if refrigerant leaks during installation, ventilate the room. Use appropriate tools for high pressure refrigerant. When pumping down refrigerant , stop the compressor before disconnecting the refrigerant pipes. During installation securely fasten the refrigerant pipes before starting the compressor. Check that refrigerant gas does not leak after the completion of installation.
  • Page 5 [1] Cautions for service (1) Perform service after recovering the refrigerant left in unit completely. (2) Do not release refrigerant in the air. (3) After completing service, charge the cycle with specified amount of refrigerant. (4) When performing service, install a filter drier simultaneously. Be sure to use a filter drier for new refrigerant.

  • Page 6: Specifications

    SPECIFICATIONS OCH531...

  • Page 7: Part Names And Functions

    PART NAMES AND FUNCTIONS <EHST20C-*M*HB/*M*B> (Split model system) Number Component Automatic air vent Pressure relief valve Expansion vessel Main controller Control and electrical box Immersion heater (Only for EHST0C-*M*HB) DHW tank 3-way valve Water circulation pump Manual air vent Booster heater Drain cock (Booster heater) Strainer valve Flow switch...
  • Page 8 <EHST20C-VM6SB> (Solar split model system) Number Component Automatic air vent Pressure relief valve Expansion vessel Main controller Control and electrical box DHW tank 3-way valve Water circulation pump Manual air vent Booster heater Drain cock (Booster heater) Strainer valve Flow switch Drain cock (Primary circuit) Drain cock (DHW tank) Plate heat exchanger...
  • Page 9 <EHPT20X-*M*HB/*M*B (except EHPT20X-VM2HB)> (Packaged model system) Number Component Automatic air vent Pressure relief valve Expansion vessel Main controller Control and electrical box Immersion heater (Only for EHPT0X-*M*HB) DHW tank 3-way valve Water circulation pump Manual air vent Booster heater Drain cock (Booster heater) Strainer valve Flow switch Drain cock (Primary circuit)

  • Page 10: Outlines And Dimensions

    OUTLINES AND DIMENSIONS <Unit: mm> 5-1. Technical Drawings Air vent Pressure relief valve G1/2 Main controller Temperature and pressure relief valve and its access plate (EHPT0X-VMHB)only) Terminal block Front panel <Front> <Right side> <Left side> Letter Pipe description Connection size/type DHW outlet connection  mm/Compression Cold water inlet connection...

  • Page 11: Wiring Diagram

    WIRING DIAGRAM EHST20C-VM6HB WIRING DIAGRAM 6-1. EHST20C-VM6HB Cylinder unit powered Cylinder unit powered by independent source. via outdoor unit Power supply Power supply To outdoor To outdoor to Immersion heater to Booster heater Power supply unit unit ~/N 230V 50Hz...
  • Page 12 EHST20C-YM9HB WIRING DIAGRAM 6-2. EHST20C-YM9HB Cylinder unit powered Cylinder unit powered by independent source. via outdoor unit Power supply Power supply To outdoor To outdoor to Booster heater Power supply to Immersion heater unit unit ~/N 230V 50Hz ~/N 230V 50Hz 3~ 400V 50Hz ECB2 ECB1...
  • Page 13 EHST20C-VM6B WIRING DIAGRAM 6-3. EHST20C-VM6B Cylinder unit powered Cylinder unit powered by independent source. via outdoor unit Power supply Power supply To outdoor To outdoor to Booster heater Power supply to Immersion heater unit unit ~/N 230V 50Hz ~/N 230V 50Hz ~/N 230V 50Hz ECB2 ECB1...
  • Page 14 EHST20C-YM9B WIRING DIAGRAM 6-4. EHST20C-YM9B Cylinder unit powered Cylinder unit powered by independent source. via outdoor unit Power supply Power supply To outdoor To outdoor to Booster heater Power supply to Immersion heater unit unit ~/N 230V 50Hz ~/N 230V 50Hz 3~ 400V 50Hz ECB1 ECB2...
  • Page 15 EHST20C-VM6EB WIRING DIAGRAM 6-5. EHST20C-VM6EB Cylinder unit powered Cylinder unit powered by independent source. via outdoor unit Power supply Power supply To outdoor Power supply To outdoor to Immersion heater to Booster heater unit ~/N 230V 50Hz unit ~/N 230V 50Hz ~/N 230V 50Hz ECB2 ECB1...
  • Page 16 EHST20C-YM9EB WIRING DIAGRAM 6-6. EHST20C-YM9EB Cylinder unit powered Cylinder unit powered via outdoor unit by independent source. Power supply Power supply To outdoor To outdoor to Booster heater Power supply to Immersion heater unit unit ~/N 230V 50Hz 3~ 400V 50Hz ~/N 230V 50Hz ECB2 ECB1...
  • Page 17 EHST20C-VM6SB WIRING DIAGRAM 6-7. EHST20C-VM6SB Cylinder unit powered Cylinder unit powered by independent source. via outdoor unit Power supply Power supply To outdoor To outdoor to Booster heater Power supply to Immersion heater unit unit ~/N 230V 50Hz ~/N 230V 50Hz ~/N 230V 50Hz ECB2 ECB1...
  • Page 18 Cylinder unit powered 6-8. EHPT20X-VM2HB Cylinder unit powered via outdoor unit by independent source. Power supply Power supply To outdoor To outdoor to Booster heater Power supply to Immersion heater unit unit ~/N 230V 50Hz ~/N 230V 50Hz ~/N 230V 50Hz ECB2 ECB1 CN01...
  • Page 19 EHPT20X-VM6HB WIRING DIAGRAM 6-9. EHPT20X-VM6HB Cylinder unit powered Cylinder unit powered by independent source. via outdoor unit Power supply Power supply To outdoor To outdoor to Booster heater Power supply to Immersion heater unit unit ~/N 230V 50Hz ~/N 230V 50Hz ~/N 230V 50Hz ECB2 ECB1...
  • Page 20 EHPT20X-YM9HB WIRING DIAGRAM 6-10. EHPT20X-YM9HB Cylinder unit powered Cylinder unit powered by independent source. via outdoor unit Power supply Power supply To outdoor To outdoor to Booster heater Power supply to Immersion heater unit unit ~/N 230V 50Hz ~/N 230V 50Hz 3~ 400V 50Hz ECB1 ECB2...
  • Page 21 EHPT20X-VM6B WIRING DIAGRAM 6-11. EHPT20X-VM6B Cylinder unit powered Cylinder unit powered by independent source. via outdoor unit Power supply Power supply To outdoor To outdoor to Booster heater Power supply to Immersion heater unit unit ~/N 230V 50Hz ~/N 230V 50Hz ~/N 230V 50Hz ECB1 ECB2...
  • Page 22 EHPT20X-YM9B WIRING DIAGRAM 6-12. EHPT20X-YM9B Cylinder unit powered Cylinder unit powered by independent source. via outdoor unit Power supply Power supply To outdoor To outdoor to Booster heater Power supply to Immersion heater unit unit ~/N 230V 50Hz 3~ 400V 50Hz ~/N 230V 50Hz ECB2 ECB1...

  • Page 23: Dip Switch Setting

    6-13. Dip switch setting Located on the FTC4 printed circuit board are 4 sets of small white switches known as Dip switches. The Dip switch number is printed on the circuit board next to the relevant switches. The word ON is printed on the circuit board and on the Dip switch block itself.

  • Page 24: Field Wiring

    FIELD WIRING Breaker abbreviation Meaning Earth leakage circuit breaker for booster heater ECB1 Earth leakage circuit breaker for immersion heater ECB Terminal block 1 Option 1: Cylinder unit powered via outdoor unit Cylinder unit <1 phase> Outdoor unit To control Power Wiring board...
  • Page 25 <3 phase> Cylinder unit Outdoor unit To control board Power supply Wiring Earth circuit leakage 400V breaker 50Hz circuit breaker Isolating switch ECB1 booster Wiring Power heater circuit supply (Primary circuit) breaker 400V Isolating 50Hz switch ECB2 Immersion Power Wiring heater supply circuit...
  • Page 26 Option 2: Cylinder unit powered by independent source. If the cylinder unit and outdoor unit have separate power supplies, the following Initial settings Black (Power supplied by requirements MUST be carried out: CN01 outdoor unit) Cylinder unit • Change the connector connections in the control and electrical box of control board the cylinder unit (see Figure 7-3) •...
  • Page 27 <3 phase> Cylinder unit Wiring Power circuit To control supply breaker Earth board leakage Isolating 0V circuit 50Hz switch breaker Outdoor unit Power Wiring supply circuit Earth breaker leakage 400V 50Hz circuit Isolating breaker switch ECB1 Wiring Power circuit booster supply breaker heater...

  • Page 28: Water System Diagram

    WATER SYSTEM DIAGRAM Refrigerant pipe Water pipe Plate heat exchanger <EHST0C-*M*HB/ *M*B> (Split model system) Flexible hose Booster heater 1, Drain cock (booster heater) Pump valve Cold water Water circulation pump 1 3-way valve Manual air vent Drain Manometer 10. Pressure relief valve ( bar) 11.
  • Page 29 * EN60335/Type 3000W single phase 230V 50Hz, length 460 mm 000 W, 0 V and outlet pipework. No valve should be fitted ** Use only Mitsubishi Electric service parts as a direct replacement. between the expansion valve (item 35) and the DHW tank capacity 00 L cylinder unit (safety matter).
  • Page 30 Water pipe <EHPT20X-*M*HB/*M*B (except EHPT20X-VM2HB)> Plate heat exchanger (Packaged model system) Booster heater 1, Drain cock for booster heater) Pump valve Water circulation pump 1 Cold water 3-way valve Manual air vent Drain Manometer 10. Pressure relief valve ( bar) 11.
  • Page 31 Local system 1-zone temperature control Zone1 Zone1 2-zone temperature control Zone1 Zone 1-zone temperature control with boiler 2-zone temperature control with boiler Zone1 Zone1 Zone 1. Zone1 heat emitters (e.g. radiator, fan coil unit) (field supply) . Mixing tank (field supply) .
  • Page 32 Filling the cylinder unit (Primary circuit) Filling 1. Check all connections including factory fitted ones are tight. 2. Insulate pipework between cylinder unit and outdoor unit. 3. Thoroughly clean and flush, system of all debris. (see section 4.2 for instruction.) 4.

  • Page 33: Controls

    CONTROLS 9-1. Main Controller <Main controller parts> Letter Name Function Screen in which all information is displayed Screen Access to system settings for initial set up and Menu modifications. Back Return to previous menu. Confirm Used to select or save. (Enter key) Power/Holiday If system is switched off pressing once will turn system on.
  • Page 34 <Main Controller Menu Tree> Unrestricted access Initial Installer only Main screen Information Option Forced DHW ON/OFF ON/Prohibited/Timer Heating ON/Prohibited/Timer Holiday Active/Non active Set time Main menu Normal/Eco Edit DHW max. temp. DHW max. temp. drop DHW max. operation time DHW mode restriction Legionella Active/Non active Edit...
  • Page 35 <Main Controller Menu Tree> Initial Unrestricted access Main screen Installer only Main menu Service (Password protected) Manual operation Function settings Thermistor adjustment Auxiliary settings Economy settings for pump ON/OFF Delay Electric heater (Heating) ON/OFF Delay ON/OFF Electric heater (DHW) Delay Mixing valve control Running Interval...

  • Page 36: Service Menu

    9-2. Service Menu The service menu provides functions for use by installer or service engineer. It is NOT intended the home owner alters settings within this menu. It is for this reason password protection is required to prevent unauthorised access to the service settings.
  • Page 37 Function settings Function Setting allows the setting of auto recovery after power failure only. 1. From the service menu use F1 and F2 to highlight Function Setting. 2. Press CONFIRM. 3. Ensure the Ref address and unit number are displayed to the right. 4.
  • Page 38 <Electric heater (Heating)> From the Auxiliary settings menu highlight Electric heater (Heating). Press CONFIRM. The Electric heater (Heating) screen is displayed. Press F1 button to switch the function ON/OFF. Use F3 and F4 buttons to adjust the time period of heat pump only operation before the booster heater will assist in space heating.
  • Page 39 Heat source setting The default heat source setting is heat pump and all electric heaters present in the system to be operational. This is referred to as Standard operation on the menu. From the service menu use F1 and F2 buttons to scroll through list until Heat Source Setting is highlighted.
  • Page 40 <Cold weather function> For extremely low outdoor ambient temperature conditions when the heat pump’s capacity is restricted the heating or DHW is provided only by the electric booster heater (and immersion if present). This function is intended for use during extreme cold periods only.
  • Page 41 <Floor dry up function> The Floor dry up function automatically changes the target hot water temperature in stages to gradually dry concrete when this particular type of underfloor heating system is installed. 1. Turn off the system using the main controller. 2.
  • Page 42 Running information This function shows current temperature and other data of main component parts of both the indoor and outdoor units. 1. From the Service menu highlight Running information. 2. Press CONFIRM. 3. Press F3 and F4 buttons to set the Ref. address. 4.
  • Page 43 Password protection Password protection is available to prevent unauthorised access to the service menu by untrained persons. From the service menu use F1 and F2 buttons to scroll through list until is highlighted. Press CONFIRM. When password input screen is displayed use buttons F1 and F2 to move left and right between the four digits, F3 to lower the selected digit by 1, and F4 to increase the selected digit by 1.
  • Page 44 SD card The use of an SD memory card simplifies the main controller settings in the field. *Ecodan service tool (for use with PC tool) is necessary for the setting. <SD Main RC> From the SD card setting use F1 and F2 buttons to scroll through list until Main RC”...
  • Page 45 <Table 9--1> Request Request content Range Unit code Displays error history. ("– –" is displays if no history is present.) Error history 1 (latest) Code Displays error history. ("– –" is displays if no history is present.) Error history  (second to last) —...
  • Page 46 Indoor unit switch setting display (Request code: 162 to 165) 0: OFF 1: ON 0: OFF 1: ON SW1, SW, SW, SW4 SW1, SW, SW, SW4 Display Display 00 00 00 40 00 01 00 41 00 0 00 4 00 0 00 4 00 04...
  • Page 47 Indoor unit switch setting display (Request code: 162 to 165) 0: OFF 1: ON 0: OFF 1: ON SW1, SW, SW, SW4 SW1, SW, SW, SW4 Display Display 00 80 00 C0 00 81 00 C1 00 8 00 C 00 8 00 C 00 84...
  • Page 48 Output signal display (Request code: 175/553) Please refer to Table 2 on relevant wiring diagram whilst using the following. 0: OFF 1: ON 0: OFF 1: ON Display Display xx 00 xx 40 xx 01 xx 41 xx 02 xx 42 xx 43 xx 03 xx 04...
  • Page 49 Output signal display (Request code: 175/553) Please refer to Table 2 on relevant wiring diagram whilst using the following. 0: OFF 1: ON 0: OFF 1: ON Display Display xx C0 xx 80 xx C1 xx 81 xx C2 xx 82 xx C3 xx 83 xx C4...
  • Page 50 Output signal display (Request code: 175/553) Mixing valve state Please refer to Table 2 on relevant wiring diagram whilst using the following. Mixing valve state 0: OFF 1: ON Stop Display Stop Open 00 xx Close 01 xx 02 xx 03 xx 04 xx 05 xx...
  • Page 51 Input signal display (Request code: 176/554) Please refer to Table 1 on relevant wiring diagram whilst using the following. 0: OFF (open) 1: ON (short) 0: OFF (open) 1: ON (short) Display Display 00 00 00 40 00 01 00 41 00 0 00 4 00 0...
  • Page 52 <Emergency operation (Heater)> In Emergency operation mode the outdoor heat pump unit will not operate. Heat- ing for DHW and space heating is provided by the booster heater and the tank immersion heater (if installed). Space heating flow temp is restricted 40°C if an immersion heater is not present on the DHW tank then the booster heater will also indirectly heat the DHW.

  • Page 53: Troubleshooting

    TROUBLESHOOTING 10-1. Troubleshooting <Summary of self diagnosis based on Error Codes and Service Procedures> Present and past Error codes are logged and displayed on the main controller or control board of the outdoor unit. Please refer to the table below and subsequent explanations to diagnose and remedy typical problems that may occur in the field. Unit Condition Error Code Action...
  • Page 54 10-4. Self diagnosis and action Check if Dip SW is set correctly. (Refer to Chapter 6-1.) Error code Title and display conditions Possible Cause Diagnosis and action Insufficient system head Circulation water temperature overheat Refer to table in section 10-6. to determine protection if system pump meets requirements.
  • Page 55 Error code Title and display conditions Possible Cause Diagnosis and action Connector/terminal wire has become P1/P/L5/LD Indoor unit temperature thermistor failure Visually check the terminals and connec- * The thermistors subject to failure can be detached or loose wiring. tions and reattachas appropriate. checked in “Request code: 567”...
  • Page 56 Error code Title and display conditions Possible Cause Diagnosis and action Heating operation error THW1 has become detached from its Visually inspect location and reattach as * “” is displayed in “Request code: 567” in “Run- holder. necessary. ning information”. Booster heater fault Electrically test to determine fault.
  • Page 57 Error code Title and display conditions Possible Cause Diagnosis and action Low primary circuit (Zone2 side) flow rate Insufficient system head If more head required either add an pump of the same size or replace existing pump. detected by flow switch Reduced flow in primary water circuit Check circulation pump (See 10-6.
  • Page 58 Error code Title and display conditions Possible Cause Diagnosis and action 1. Contact failure with transmission cable 1. Check connection cable for damage or E0/E4 Main controller communication failure loose connections at the FTC4 and main (Reception error) Error code E0 is displayed if main controller does controller terminals.
  • Page 59 Error code Title and display conditions Possible Cause Diagnosis and action 1. Connection fault with wireless receiver- 1. Check the connections to the wireless re- Indoor unit/wireless receiver communication FTC4 connection ceiver and FTC4 have not become loose failure Error code J0 is displayed when the FTC4 can and that the connecting cable is not dam- not receive data from the wireless receiver for 1 aged.
  • Page 60 10-5. Troubleshooting by inferior phenomena Fault symptom Possible cause Explanation - Solution 1. There is no power supply to main 1. Check LED2 on FTC4. (See 6. WIRING DIAGRAM.) Main controller display is blank. controller. (i) When LED is lit. Check for damage or contact failure of the main controller wiring.
  • Page 61 Contact your Mitsubishi Electric dealer. 7. Immersion heater cut-out tripped. 7. Check immersion heater thermostat and press reset button, located on im- mersion heater boss, if safe.
  • Page 62 Contact your Mitsubishi Electric dealer. 5. Immersion heater cut-out has been triggered. 5. Check immersion heater thermostat and press reset button located on im- mersion heater boss, if safe.
  • Page 63 Fault symptom Possible cause Explanation - Solution In 2-zone tempera- When Zone1 and Zone2 are both in heating Normal action no action necessary. mode, the hot water temperature in Zone2 ture control, only does not exceed that in Zone1. Zone does not Faulty wiring of motorized mixing valve Refer to installation manual, "5.3 Wiring for 2-zone temperature control".
  • Page 64 Fault symptom Possible cause Explanation - Solution Water discharges from If continual – field supplied pressure Check function of pressure reducing valve and replace if necessary. expansion relief valve reducing valve not working. - part of Inlet Control If continual – expansion relief valve may be Turn the handle on the expansion relief valve to check for foreign objects Group damaged.
  • Page 65 10-6. Checking component parts' function Part Name Check Points Water circulation pump <Water circulation pump characteristics> <EHST0 series> 80.0 Speed 5 (Default setting) 70.0 Speed 4 Speed  BROWN 60.0 Speed  PWM input signal Signal cable Speed 1 BLUE 50.0 Signal ref.
  • Page 66 Part Name Check Points Measure the resistance between the terminals with a tester. Booster heater Thermostat (90 °C) and thermal cut out (11 °C) Terminal Normal Abnormal 90 °C 121 °C 110(±35)mΩ Manual reset Thermal 9-10 Open or Short cut-out water thermostat kW heater (0V, 1 phase)
  • Page 67 Part Name Check Points 3-way valve (1) Check the movement of the red indicator. The red indicator normally points <DHW> <Heating> to A in DHW mode and to B in Heating mode as shown to the left. (2) If each indicator position is correct but the 3-way valve does not work prop- Motor erly, the motor may not fit onto the valve securely, so remove the motor by pressing the release button, and reinstall it.
  • Page 68 10-7. Test point diagram FTC4 (Controller board) 6.3A/250V 6.3A/250V OUT10 (TBO.1 1-2) Signal output (Boiler) (non-voltage contact) CN01 Power supply CNP1/OUT1 (TBO.1 3-4) (230V AC) Water circulation pump1 (230V AC) OUT2 (TBO.1 5-6) Water circulation pump2 (Field supply) (230V AC) CN3C OUT3 (TBO.1 7-8) Transmission...

  • Page 69: Disassembly Procedure

    ● Allow parts to cool. ● Do not expose the electric parts to water. ● When replacing or servicing water circuit parts, drain system first. EHST20C-VM6HB, EHST20C-YM9HB, EHST20C-VM6B, EHST20C-YM9B, EHST20C-VM6EB, EHST20C-YM9EB, EHST20C-VM6SB, EHPT20X-VM2HB, EHPT20X-VM6HB, EHPT20X-YM9HB, EHPT20X-VM6B, EHPT20X-YM9B Check individual illustrations and positions of the parts by referring to the parts catalog included in this manual.
  • Page 70 PHOTOS DISASSEMBLY PROCEDURE Control box cover 3. How to remove the electrical parts Photo 3-1 fixing screws (Steps (1) through (3) are applied to all the following parts.) <Control box cover> (Photo 3-1) (1) Remove the front panel. (Refer to Procedure 1). (2) Remove the 4 screws holding the control box cover.
  • Page 71 (Photo CN2F connector 4-) Band (for pipe cover) w The photos shown are of the EHST20C-VM6HB Note: model. Disconnect the field wiring as necessary. Photo 4-2 Photo 4-3...
  • Page 72 DISASSEMBLY PROCEDURE PHOTOS 5. How to remove water pump/ pump valve Photo 5-1 <Water pump> Nut (G1") (1) Remove the front panel. (Refer to Procedure 1.) Gasket(G1") (2) Remove the control box cover. (Refer to Procedure 3.) () Disconnect the CNP1 and CNPWM connector on the Pump valve controller board and release the lead wire from the 2 handle (upper)
  • Page 73 DISASSEMBLY PROCEDURE PHOTOS 6. How to remove the 3-WAY VALVE / 3-WAY VALVE MOTOR Photo 6-1 (1) Remove the front panel. (Refer to Procedure 1.) (2) Remove the control box. (Refer to Procedure 4.) (3) Remove the 3-way valve motor from the 3-way valve while pressing the button on the front of the motor that is with motor cap (viewed from the front of the cylinder unit).
  • Page 74 DISASSEMBLY PROCEDURE PHOTOS 7. How to remove the flow switch Photo 7-1 (1) Remove the front panel. (Refer to Procedure 1.) (2) Remove the control box cover. (Refer to Procedure 3.) Lead wire Flow switch (3) Disconnect the CN2F connector on the controller board. (Photo 4-1) (4) Release the lead wire from the 5 bands and 2 cable straps.
  • Page 75 DISASSEMBLY PROCEDURE PHOTOS Earth leakage circuit Control box 8. How to remove the booster heater Photo 8-1 breakers (ECB1, ECB) (1) Remove the front panel. (Refer to Procedure 1.) (2) Remove the control box cover. (Refer to Procedure 3.) Controller () Disconnect the CNBHT connector on the controller board board, and the 4 booster heater lead wires wired to the...
  • Page 76 DISASSEMBLY PROCEDURE PHOTOS 9. How to remove the thermostat/immersion heater Photo 9-1 <Thermostat> (1) Remove the front panel. (Refer to Procedure 1.) (2) Peel off the water-proof tapes on the plastic head of the thermostat in order to reveal the thermostat terminals, and disconnect the lead wires from the terminals.
  • Page 77 DISASSEMBLY PROCEDURE PHOTOS 10. How to remove the plate heat exchanger Photo 10-1 Bands Pump frame (1) Remove the front panel. (Refer to Procedure 1.) (2) Pump down the refrigerant circuit and close the stop valve at the outdoor unit side. (Refer to 1. SUPPLEMENTARY INFORMATION.) (3) Remove the control box.
  • Page 78 DISASSEMBLY PROCEDURE PHOTOS 10. How to remove the plate heat exchanger Photo 10-4 (10) Displace the plate heat exchanger together with the refrigerant pipes, the water pipe and the flexible hose to the front of the cylinder unit while feeding the top ends of the 2 refrigerant pipes though the openings in the top panel and remove the heat exchanger unit from the cylinder unit.
  • Page 79 DISASSEMBLY PROCEDURE PHOTOS 12. How to remove the pressure relief valve / manometer / air Photo 12-1 vent (automatic) (1) Remove the front panel. (Refer to Procedure 1.) (2) Swing the control box to the front. (Refer to Procedure 4.) <Manometer>...
  • Page 80 DISASSEMBLY PROCEDURE PHOTOS 13. How to remove the expansion vessel Photo 13-1 Expansion vessel Flare joint Flare nut (1) Remove the front panel. (Refer to Procedure 1.) (2) Swing the control box to the front. (Refer to Procedure 4.) (3) Remove the flare nut using two spanners: one to hold the flare joint and the other to turn the flare nut.
  • Page 81 DISASSEMBLY PROCEDURE PHOTOS Photo 16-1 Drain cock 16. How to remove the drain cock (primary circuit) (booster heater side) (1) Remove the front panel. (Refer to Procedure 1.) Booster heater side () Remove the drain cock from the booster heater by turning the drain cock.
  • Page 82 PHOTOS DISASSEMBLY PROCEDURE 19. Remove the liquid refrigerant temp. thermistor (TH2) Photo 19-1 Thermistor <THW1> / flow water temp. & return water temp. thermistor (THW1,THW2) / tank water temp. thermistor (THW5) (1) Remove the front panel. (Refer to Procedure 1.) (2) Remove the control box cover.
  • Page 83 PHOTOS DISASSEMBLY PROCEDURE 20. How to remove the side panels Photo 20 Side panel (Right) (1) Remove the front panel. (Refer to Procedure 1.) Screws (2) Remove the side panel by removing 12 screw fixing the (Top panel) side panels (6 screws each on the right and left panels). Side panel (Left) Note: Photo 20 shows the right side panel only.
  • Page 84 Notes on replacing the parts Replacement of the parts listed below requires the following procedure. After the parts are removed, eliminate loctite on threads by applying loctite remover, apply new loctite, and then install and tighten the parts to the specified tightening torques below.

  • Page 85: Supplementary Information

    SUPPLEMENTARY INFORMATION Refrigerant collecting (pumpdown) for split model systems only Refer to “Refrigerant collection” in the outdoor unit installation manual or service manual. Back-up operation of boiler Heating operation is backed up by boiler. For more details, refer to the installation manual of PAC-TH011HT-E. <Installation &...

  • Page 86: Service And Maintenance

    SERVICE AND MAINTENANCE Engineers Forms Should settings be changed from default, please enter and record new setting in ‘Field Setting’ column. This will ease resetting in the future should the system use change or the circuit board need to be replaced. Commissioning/Field settings record sheet Default set- Field...
  • Page 87 (From the previous page.) Engineers Forms Commissioning/Field settings record sheet (continued from the previous page) Default Field Main controller screen Parameters Notes setting setting Heat source setting Service menu Standard/Heater/Boiler/Hybrid * Standard Freeze stat function Outdoor ambient temp. ( - 0°C) Operation set- 5°C tings...
  • Page 88 Annual Maintenance Log Book Engineer name Contractor name Site name Site number Cylinder unit maintenance record sheet Warranty number Model number Serial number Frequency Mechanical Notes Turn OFF water supply, drain DHW tank, remove mesh from strainer clean and replace in strainer. *1 Keep water supply OFF, open hot water taps and check the primary-side expansion vessel charge pressure.
  • Page 89 OCH531...
  • Page 90 HEAD OFFICE : TOKYO BLDG., 2-7-3, MARUNOUCHI, CHIYODA-KU, TOKYO 100-8310, JAPAN Copyright 2012 MITSUBISHI ELECTRIC CORPORATION New publication, effective Sep. 2012 Distributed in Sep. 01 No. OCH51 Specifications are subject to change without notice. Made in Japan...

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