• Caleffi - iSolar Plus Contoller - 257260A PV2

    - 2 Relays - Power Input 24 volts DC

    Product ID • 257260APV200

  • $219.75
  • Quantity:
  • Free Ground Shipping


Caleffi iSolar Plus 257260A PV2 is a multi-functional temperature differential controller with add-on system functions. The Caleffi iSolar PLUS 257260A PV2 can be used for a wide variety of solar water heating applications. Preset factory defaults are defined for control of a standard solar water heating system with a second relay (some models) to divert any surplus heat. The auxiliary relay can be used to maintain the tank temperature, protect the system from overheating, or use another source to heat the storage tank.

This controller features a large Liquid Crystal Dispaly (LCD) user interface with three function keys. The easy-to-use icons assist to operate and customize a solar heating system.  The Calleffi iSolar Plus with 1 pump speed control triac and includes 2 temperature sensors and data connection and runs on 24 volts.

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Manuals & Docs

Technical Specs

Caleffi Solar Controller iSolar2 - 257260A PV2 Techs and Specs

  • Selectable programs
  • Power supply
    24 Volts
  • Sensors
    4 included
  • Inputs
    4 PT1000 temp sensors
  • Max tank temp range
    35 to 205 Degrees F
  • Max collector temp range
    210 to 375 Degrees
  • kWh (BTU) calculation flow input
    0 to 5 GPM
  • Max. Solar collector arrays
  • Max. Solar Storage tanks
  • Drainback pump peed control
  • Collector freeze protection
  • Evacuated tube collector function
  • Min collector temperature
  • Collector cooling functions
  • Tank (nighttime) cooling
  • Emergency shutdown functions
  • Operating hours counter
  • Energy metering measurement
  • Vbus data commincation

Caleffi Solar Controller iSolar2 - 257260A PV2 Features

  • Delta T Controller - When the switch-on difference is reached, the pump is activated until the differential temperature drops below
  • Maximum tank temperature - When the adjusted maximum tank temperature is exceeded, the pump switches off
  • Collector emergency shutdown - If adjusted collector temperature is exceeded, the solar pump is switched off
  • System cooling - If the temperature rises to the maximum collector temperature the solar pump remains on until the temperature drops
  • Minimum collector temperature - a minimum set temperature which must be exceeded before the solar pump is switched-on
  • Antifreeze function - If the adjusted temperature drops, the solar pump is switched on to protect the fluid from freezing
  • Tank Cooling Function - In the evening, the solar pump continues running until the storage tank is cooled down
  • Tube Collector Function - The controller measures an increase of heat rise in the collector and adjusts operation for maximum efficiency
  • Heat Generation Measrurement KWh (BTu)- The heat generated is measured by the flow and the temperature of feed and return sensors
  • Operating hours counter - Operating hours counter stores the solar operating hours of the respective relay
  • Manual operating mode - For control and servicing, the operating mode of the controller can be switched manually

Info & Links

Solar Heating and Solar Domestic Hot Water with Flat Panels Example

Solar Heating / Solar Domestic Water with Evacuated Tubes and Boiler Example

Solar Domestic Hot Water, Solar Heating and Solar Pool Heating with Flat Panels

Solar Domestic Water with a Water Heater as a Backup Heat Source Example

Solar Panels for Domestic Water and Space Heating with a Boiler as the Backup Heat Source Example

Solar Panels for Domestic Water and Space Heating Pre-Heating into a Gas Combination Boiler Example

Solar Space Heating with a Backup Gas/Electric Boiler Installation Diagram

Hot Water Output examples for 3 locations

Solar Hot Water System Install - Waitsfield Vermont

Solar Hot Water System Install - Maine

Solar Hot Water System Install - Upstate New York

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