Series description


Glandless circulation pump with threaded connection


Domestic hot water circulation systems in industry and building services.

This circulator is suitable for drinking water only.

Type key

Example:Wilo-Star-Z 20/1Wilo-Star-Z 15 TT
StarStandard pump
ZCirculation pump
20/Nominal connection diameter
1Nominal delivery head [m]
TTwith built-in time switch and temperature control (only Z 15 TT)
EMAC motor (1~)
DMThree phase motor (3~)
-33 speed stages

Special features/product advantages

  • AC pumps with electrical quick connection
  • All plastic parts that come into contact with the fluid fulfil KTW recommendations
  • Thermal insulation as standard for Star-Z 15 TT.
  • Star-Z 15 TT with integrated timer and thermostat, LC display with symbolic language, Green Button Technology and automatic detection of the thermal disinfection of the domestic hot water tank, as well as ball shut-off valve on suction side and non-return valve on pressure side.

Technical data

  • Constant speed or, for Star‐Z...-3, three selectable speed stages
  • Fluid temperature:
    • Drinking water up to 3.21 mmol/l (18 °dH): max. +65°C, in short-time duty (2 h) up to +70°C
  • Mains connection 1~230 V, 50 Hz or, for Star‐Z 25/2 DM, 3~400 V, 50 Hz
  • Protection class IP 44 (IP 42 for Star-Z 15 TT)
  • Nominal diameter Rp ½, Rp 1
  • Max. operating pressure 10 bar


Operating modes

  • Speed stage switching (Star‐Z -3 only)

Manual functions

  • Setting of the speed stages (1 speed stage, 3 speed stages with Star-Z...-3 pumps)

Automatic functions

  • Time switching function for programming of 3 switch-on or switch-off times (Z 15 TT only)
  • Temperature control for maintaining a constant return temperature in the domestic hot water circulation system (Z 15 TT only)
  • Thermal disinfection routine (detection and support of thermal disinfection of the domestic hot water tank) (only Z 15 TT)
  • Blocking protection (Z 15 TT only)

Signal and display functions

  • LCD screen for display of pump data and fault codes (Z 15 TT only)


  • Wrench attachment point on the pump body (Star‐Z 25 only)
  • Cable inlet possible from both sides (Star‐Z 20/..., Star‐Z 25/... only)
  • quick connection with spring clips
  • Blocking-current proof motor
  • Integrated non-return valve on the pressure side (only Star-Z 15 TT)
  • Integrated ball shut-off valve on suction side (only Star-Z 15 TT)
  • Including time switch (only Z 15 TT)


  • Pump housing:
    • Brass: Star-Z 15
    • Bronze: Star‐Z 20, ‐Z 25
  • Impeller: Plastic
  • Shaft:
    • Stainless steel: Star-Z 15
    • Oxide ceramic: Star‐Z 20, ‐Z 25
  • Bearing: Carbon, synthetic resin impregnated

Scope of delivery

  • Pump
  • Gaskets for threaded connection
  • Installation and operating instructions
  • Thermal insulation (Star-Z 15 TT only)


  • Screwed connections
  • Adapter fittings
  • Thermal insulation shells for Star-Z 20, 25
  • Special brass inserted parts for screw-end pumps:
    Male thread/inner soldering connection
  • Wilo‐S1R‐h switchgear plug-in module for Star‐Z 20/1, Z 25/2 EM (single-phase version)
  • Wilo‐SK 601N switchgear in connection with Wilo‐SK 602N (as contactor) for Star‐Z 25/2 DM (three-phase version)
  • Wilo‐SK 601N switchgear for timed On/Off switching for Star‐Z 20, 25

Duty chart

Pump curves


General overview

Edition 2017
Page format A4
Number of pages 72

PDF (46 MB)


Wilo digital timer (Star-Z 20/...-Z 25)

Article Number 4148573
Edition 1005
Version number 01
Page format A6
Number of pages 13

PDF (1 MB)


Wilo-plug-in module S1R-h (Star-Z 20/...-Z 25)

Article Number 4148574
Edition 1005
Version number 01
Page format A6
Number of pages 11

PDF (756 kB)


Wilo-Star-Z 15 TT

Article Number 4106235, 4202386
Edition 1508
Version number 01
Page format A5
Number of pages 17

PDF (1 MB)


Wilo-Star-Z 20/1, 25/2, 25/2 DM, 25/6, ZD 25/6

Article Number 4131022
Edition 1010
Version number 02
Page format A6
Number of pages 14

PDF (2 MB)



PDF: Wilo-Star-Z


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