Skip to main content
Home page Home page
Main navigation
  • Products
  • Products
    Products:
    • Air and Dirt Separators and Air Vents
      Air and Dirt Separators and Air Vents:
      • 577 XF Xtra Filtration Magnetic Dirt Separators
        577 XF Xtra Filtration Magnetic Dirt Separators:
        • 577 XF
      • Air Vents
        Air Vents:
        • Accessories
        • DISCALAIR® Automatic (up to 4.5 SCFM)
        • HYGROCAL™ Radiator Air Vent
        • MAXCAL™ Automatic (up to 9.0 SCFM)
        • MINICAL® Automatic (up to 1.75 SCFM)
        • Manual
        • ROBOCAL™ Automatic (up to 1.75 SCFM)
        • VALCAL™ Automatic (up to 2.5 SCFM)
      • DIRTMAG® Magnetic Dirt Separators
        DIRTMAG® Magnetic Dirt Separators:
        • Accessories
        • DIRTMAG® (ANSI Flange)
        • DIRTMAG® (Composite)
        • DIRTMAG® Pro (Brass)
      • DISCALDIRTMAG™ Air and Magnetic Dirt Separators
        DISCALDIRTMAG™ Air and Magnetic Dirt Separators:
        • Accessories
        • DISCALDIRTMAG™ (ANSI Flange)
        • DISCALDIRTMAG™ (Brass)
        • DISCALDIRTMAG™ (Union)
      • DISCALDIRT® Air and Dirt Separators
        DISCALDIRT® Air and Dirt Separators:
        • Accessories
        • DISCALDIRT® (ANSI Flange)
        • DISCALDIRT® (Brass)
      • DISCAL® Air Separators
        DISCAL® Air Separators:
        • Accessories
        • DISCAL® (ANSI Flange)
        • DISCAL® (Brass)
    • Backflow Prevention and Safety Devices
      Backflow Prevention and Safety Devices:
      • Backflow Preventers
        Backflow Preventers:
        • Dual Check (DuC)
        • Dual Check with atmospheric vent (DuC-AV)
        • Reduced Pressure Principle (RP)
      • Safety Devices
        Safety Devices:
        • Vacuum Relief Valves (VRV)
    • Balancing Valves
      Balancing Valves:
      • Dynamic
        Dynamic:
        • Accessories
        • FlowCal+™ (compact)
        • FlowCal+™ (y-body)
        • FlowCal™ (compact)
        • FlowCal™ (hydronics)
        • FlowCal™ (y-body)
      • Static
        Static:
        • Accessories
        • Flo-Set™
        • QuickSetter+™
        • QuickSetter™ (hydronics)
      • Thermal
        Thermal:
        • Accessories
        • ThermoSetter™ Compact
        • ThermoSetter™ Large body
        • ThermoSetter™
    • Distribution Manifolds and Mixing Stations
      Distribution Manifolds and Mixing Stations:
      • Assemblies
        Assemblies:
        • Accessories
        • TwistFlow™
      • Temperature Mixing Units
        Temperature Mixing Units:
        • Accessories
        • HydroMixer™
      • Thermostatic Manifold Mixing Stations
        Thermostatic Manifold Mixing Stations:
        • Accessories
        • Low Temperature
    • Filling Units and Boiler Trim Kits
      Filling Units and Boiler Trim Kits:
      • Automatic Filling Units
        Automatic Filling Units:
        • Accessories
        • AutoFill™ Combo
        • AutoFill™
        • Boiler Trim Kits
      • Water Treatment
        Water Treatment:
        • Accessories
        • Filling Units
        • HYDROFLUSH™ (fill and flush cart)
    • Fittings
      Fittings:
      • AutoFill™
        AutoFill™:
        • Tail pieces, union nuts, washers
      • Backflow Preventers
        Backflow Preventers:
        • Tail pieces, union nuts, washers
      • PresCal™
        PresCal™:
        • Tail pieces, union nuts, washers
      • Separators
        Separators:
        • Tail pieces, union nuts, washers
      • Small Valves
        Small Valves:
        • 1" union Fittings
        • Tail pieces, union nuts, washers
      • Threaded
        Threaded:
        • Union nuts, nipples adapters, bushings
    • Hydraulic Separators
      Hydraulic Separators:
      • 4-in-1 SEP4™
        4-in-1 SEP4™:
        • Accessories
        • SEP4™ (ANSI Flange)
        • SEP4™ (Union)
      • Hydro Separators
        Hydro Separators:
        • Accessories
        • Hydro Separator (ANSI Flange)
        • Hydro Separators (Union)
        • HydroCal™ (ANSI Flange)
    • Mixing Valves
      Mixing Valves:
      • Digital
        Digital:
        • Accessories
        • LEGIOMIX® Station
        • LEGIOMIX®
      • Thermostatic (point of distribution)
        Thermostatic (point of distribution):
        • Accessories
        • AngleMix+™
        • AngleMix™ DL
        • AngleMix™
        • MixCal+™ (high flow)
        • MixCal™
        • TankMixer™ (Thermostatic Mixing Valve Kits)
      • Thermostatic (point of use)
        Thermostatic (point of use):
        • Accessories
        • SinkMixer™
        • TubMixer™ (high flow)
        • TubMixer™ (high flow) w/ gauge
    • Pressure Reducing Valves
      Pressure Reducing Valves:
      • Diaphragm Type
        Diaphragm Type:
        • Accessories
        • PresCal™
        • Prescal™ Compact
      • Piston Type
        Piston Type:
        • PresCal™ HP
      • Two Stage PRV Kit
        Two Stage PRV Kit:
        • KIT536
    • Renewable Components and Energy Meters
      Renewable Components and Energy Meters:
      • Biomass
        Biomass:
        • Accessories
        • ThermoBloc™ (recirc and distribution units)
        • ThermoProtec™ (mixing valves)
      • Energy Meters
        Energy Meters:
        • Accessories
        • CONTECA™
      • Solar
        Solar:
        • Accessories
        • Air Vents
        • DISCAL® (air separators)
        • Mixing Valves
        • Pump Stations
        • Safety Relief Valves
    • Specialty Components and Kits
      Specialty Components and Kits:
      • Air Vents (plumbing)
        Air Vents (plumbing):
        • PLUMBVENT™
      • Anti-freeze Valves
        Anti-freeze Valves:
        • iStop®
      • Check Valves
        Check Valves:
        • Accessories
        • Check Valves (serviceable)
        • Low Lead Brass Check Valves
      • Differential Pressure Bypass
        Differential Pressure Bypass:
        • Differential Pressure Bypass Valves
      • Isolation Ball Valves
        Isolation Ball Valves:
        • Accessories
        • Isolation Valves
      • Kits
        Kits:
        • Tankless Water Heater Kits
      • Universal Flow Switch
        Universal Flow Switch:
        • Uni-Switch™
      • Y-strainers
        Y-strainers:
        • Accessories
        • NPT Y-strainer
        • Union Y-strainer (plumbing and hydronics)
        • Y-strainers (hydronics)
    • Thermostatic Radiator Valves
      Thermostatic Radiator Valves:
      • Connection Valves
        Connection Valves:
        • Accessories
        • Angled Version
        • Straight Version
      • Radiator Valve Bodies
        Radiator Valve Bodies:
        • Accessories
        • Valve Bodies (angled)
        • Valve Bodies (straight)
      • Thermostatic control heads
        Thermostatic control heads:
        • Accessories
        • Control Heads (Built-in Sensor)
        • Control Heads (Remote Sensor)
    • Zone Valves, Controls and Coil Kits
      Zone Valves, Controls and Coil Kits:
      • Motorized Ball Zone Valves
        Motorized Ball Zone Valves:
        • 2-way (high-flow, straight)
        • 2-way (straight)
        • 3-way (by-pass)
        • 3-way (diverting)
      • Motorized Zone Valves
        Motorized Zone Valves:
        • 2-way Bodies (straight flow)
        • 3-way Bodies (diverting flow)
        • Accessories
        • Actuators (normally closed)
        • Actuators (normally opened)
        • Z-one™ 2-way
      • Pressure Independent Control Valves (PICV)
        Pressure Independent Control Valves (PICV):
        • Accessories
        • FLOWMATIC® Express Coil Kit
        • FLOWMATIC®
      • Thermo-electric Zone Valves
        Thermo-electric Zone Valves:
        • Accessories
        • TwisTop™
      • Z-one™ Zone Controls
        Z-one™ Zone Controls:
        • Accessories
        • Pump Zone Controls
        • Valve Zone Controls
  • Education
    Education:
    • idronics™
    • Coffee with Caleffi™
    • Ask Caleffi Podcast
  • Company
    Company:
    • Corporate
    • The Group
    • History
    • Certifications
    • Mission
    • Portfolio
    • The Caleffi Green
  • Blog
Secondary navigation
  • News & Events
  • Contacts
    • EMEA
      • Albania - Albanian
      • Belgium - French
      • Belgium - Dutch
      • Croatia - Croatian
      • Czech Republic - Czech
      • France - French
      • Germany - German
      • Greece - Greek
      • Hungary - Hungarian
      • Italy - Italian
      • Macedonia - Macedonian
      • Netherlands - Dutch
      • Poland - Polish
      • Portugal - Portuguese
      • Romania - Romanian
      • Russia - Russian
      • Serbia - Serbian
      • Slovakia - Slovak
      • Slovenia - Slovenian
      • Spain - Spanish
      • Switzerland - French
      • Switzerland - German
      • Turkey - Turkish
      • Ukraine - Ukrainian
    • The Americas
      • Brazil - Portuguese
      • North America - English
      • South America - Spanish
    • Asia Pacific
      • China - Chinese
    Visit our International site
Anti-freeze Valves
Home /
Products /
Specialty Components and Kits /
Anti-freeze Valves /
... /
iStop®
See all products of

iStop®

175609

iStop®, Anti-freeze valve for air-to-water hydronic heat pump applications

Main navigation
  • Products
  • Education
  • Company
  • Blog
Secondary navigation
  • News & Events
  • Contacts
Footer menu
  • Cookies
  • Privacy
Caleffi S.p.a.
P.I. IT04104030962 - © 1961 - 2025 Caleffi S.p.a. | All rights reserved