HIUs

Training

Module 6 – Replace Spares

The objective for training in Part 6 is and how to replace varius components used in the Inta HIU

Replacing Components

FRont Line Spares

Front Line Spares DescriptionPart Code
Grundfos UPM3 Pump - Head and Block inc automatic airventHI29337005
Honeywell VC series DIVERTER ACTUATORHI29314005
Honeywell DIVERTER CARTRIDGE M35X1,5 HI29313005
Frese PICV Stepper ACTUATORHI29330005
Frese compact OEM cartridgeHI29329005
Pressure switch 0.7barHI29308005
Shock arrester (mechanical assembly, prevents water hammer)HI29325003
Heating Plate Heat Exchanger x 18HI28559005
DHWS Plate Heat Exchanger x 42 HI2FL12041510
Filling groupHI2FL12041510
Flow meter switchHI29338005
Pressure gaugeHI29339005
Zilmet Expansion Vessel HI29340005

Replace Pump

  • To remove the pump, first disconnect the power cable
    using a small flat face screwdriver to release the clip.
  • Using a suitably sized spanner, loosen the two nuts holding the pump in place.
  • The pump may then be removed.

IMPORTANT, always isolate electricty and turn off isolation valve and drain before working on the HIU

Replace Diverter Actuator

  • To remove the diverter actuator, first remove the
    power cable using the clip on the side as shown
  • To loosen the diverter actuator from the brass block, push in the metal clip shown
  • The diverter will then twist and pull away from the brass block revealing the diverter cartridge

IMPORTANT, always isolate electricty and turn off isolation valve and drain before working on the HIU

Replace Diverter Cartridge

*Special tool required to remove the diverter actuator cartridge

IMPORTANT, always isolate electricty and turn off isolation valve and drain before working on the HIU

Replace PICV Acuator

  • Isolate the power supply to the HIU
  • Remove the actuator head by
    unscrewing the brass nut (pictured)
  • Once the PICV Actuator is removed the cable will need to be disconnected, remove the front cover to the HIU PID using the 5 screws as shown
  • Locate the PICV Actuator connection plug (Top Right) and release this from the PCB

IMPORTANT, always isolate electricty and turn off isolation valve and drain before working on the HIU

Replace PICV Frese Cartridge

  1. To remove the PICV actuator cartridge, first remove the
    actuator head by unscrewing the brass nut.
  1. Use a suitably sized spanner to loosen the cartridge from the brass block
  1. Once this has been loosened the cartridge can be pulled from the brass body.
  1. Reverse the process for installation.

IMPORTANT, always isolate electricty and turn off isolation valve and drain before working on the HIU

Replace Pressure Switch

  • Locate the pressure switch (Bottom of the HIU next to the SRV)
  • Remove the retaining clip on the right-hand side as shown
  • Once the retaining clip is removed the pressure switch can be pulled away from the brass body as shown below
  • Once the clip has been removed, the pressure switch pulls away from the brass block
  • The pressure switch may also be unplugged from the cable by pulling the socket away from the component

IMPORTANT, always isolate electricty and turn off isolation valve and drain before working on the HIU

Replace Shock Arrester

  • Remove the screws from the bottom of the controller PID bracket to allow access to the shock arrester.
  • The PID can be pulled across to the left-hand side
  • Once there is access, use a suitably sized spanner to loosen both nuts holding the shock arrester in place.
  • The shock arrester can now be removed
  • Reverse the process for re-installation.

IMPORTANT, always isolate electricty and turn off isolation valve and drain before working on the HIU

Replace DHWS Plate Heat Exchanger

  • Pull back insulation to access x2 bolts securing the PHE bracket as shown
  • Once the bracket is removed the DHW PHE can be removed

NOTE: The PHE will still have water inside, turn upside down ASAP to avoid water damage to PCB

IMPORTANT, always isolate electricty and turn off isolation valve and drain before working on the HIU

Replace Heating Plate Heat Exchanger

  • Pull back insulation to access x2 bolts securing the PHE
    bracket as shown. (an allen Key is required to loosen these
    bolts)
  • Lift the bracket and remove the DHW PHE, once the bolts
    are removed, this is lifted away from the HIU

NOTE: The PHE will still have water inside, turn upside down ASAP

  • To access the Heating PHE, note the securing bolts pictured which are hidden until DHW PHE is removed.
  • There is one bolt either side on both brass blocks.
  • Once these are both removed, it is possible to slide the Heating PHE out from the left-hand side of the HIU
  • Reverse this process for re installation

IMPORTANT, always isolate electricty and turn off isolation valve and drain before working on the HIU

Replace Filling Group

  • To remove the filling group, ensure the cold main and secondary heating are both drained down and isolated.
  • Once isolated loosen both nuts as shown, the filling group may then by removed from the HIU.

IMPORTANT, always isolate electricty and turn off isolation valve and drain before working on the HIU

Replace Flow Meter Switch

  • Remove the screws from the bottom of the controller PID bracket to allow access to the flow sensor.
  • The PID can be pulled across to the left-hand side.
  • Disconnect the power supply to the flow sensor
  • Disconnect the power supply to the flow sensor
  • Once there is access, use a suitably sized spanner to loosen both nuts holding the flow sensor in place.
  • The flow sensor can now be removed.
  • Revers the process for re-installation.

IMPORTANT, always isolate electricty and turn off isolation valve and drain before working on the HIU

Replace Pressure Gauge

  • To remove the pressure gauge, first remove the retaining clip holding in the pressure gauge piping.
  • Once the pipe is removed from the brass block press in the two clips either side of the pressure gauge face as shown.
  • Once the gauge is no longer held into the HIU, the gauge and the pipe can be
    pulled through the gauge bracket

IMPORTANT, always isolate electricty and turn off isolation valve and drain before working on the HIU

Replace Zilmet Expansion Vessel

  • Isolate and drain down the primary flow and return (within the HIU).
  • Drain down the secondary flow and return (within the HIU).
  • Loosen the two nuts pictured and the expansion vessel connection which is located at the top of the HIU.
  • Remove the screws holding the expansion vessel support bracket in position (x4, this is located directly above the PHE’s fixed to the back of the unit).
  • Once the bracket is loose/reoved pull forward the primary flow and return pipes (these are on swivels).
  • Now this is all complete the vessel can be pulled out from the side as shown.
  • Reverse this process for re-installation.

IMPORTANT, always isolate electricty and turn off isolation valve and drain before working on the HIU

End of Module 6

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