• Caleffi iSolar WMZ G1 kWh (Btu) Heat Meter - 257202A G1

    - with Data Connection to DL2 Datalogger

    Product ID • 257202A00000

    Non-Stock Item - Allow 4-9 Business Days to Ship

  • $260.75
  • Quantity:
  • Free Ground Shipping


The iSola WMZ-G1 is an energy heat meter for thermal solar systems and conventional heating systems. The WMZ-G1 calculates energy by integrating flow rate and temperature from a Vortex Flow Sensor (VFS) Grundfos Direct Sensor and temperature difference in the flow and return piping using a Relative Pressure Sensor (RPS) Grundfos Direct Sensor. The calculated heat energy value is displayed in kWh (kilowatt hours) and stored. A memory feature guarantees that the adjusted system parameters and the calculated heat energy quantity are maintained in the case of power loss. A red/green operating control lamp continuously indicates four operating states: normal operation, measured value outside pre-selected alarm limits, defective sensor, or no supply voltage. An integrated dry contact output alarm relay can be connected to an additional signaling device or to a building management system.

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Manuals & Docs

Technical Specs

Caleffi Solar Controller iSolar4- 257202A G1 Specs

  • Housing plastic
  • Display
    4 lines LCD
  • Inputs
    2 Grundfos Direct Sensors
  • Output
    1 relay
  • Switching relay capacities
    2 (1) A 24V
  • Interface
    VBus data connection
  • Power supply
    24V AC or DC
  • Flow measuring range
    NA15015 0.25 - 3 gpm (1-12 lpm)
  • NA15016 0.50
    10 gpm (2-40 lpm)
  • Flow accuracy
  • Flow response time
    < 1 sec.
  • Relative Pressure Sensor (RPS)
  • Pressure measuring range
    0 - 150 psi (0-10 bar)
  • Pressure accuracy
    2% FS
  • Pressure response time
    < 1 sec.
  • Max. fluid temperature
    250° F
  • Temperature accuracy range
    32 - 210°F
  • Temperature accuracy
  • Temperature response time
    < 1sec.
  • Suitable fluids
    water, glycol solution
  • Max percentage of glycol
  • Bodu Material
  • Seals
  • Sensor housing
    composites (PPS, PA66)
  • Connection
    1" male union thread

Info & Links

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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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