ISO 18566-2:2017

Overview

ISO 18566-2:2017 specifies test methods and procedures to determine the heating and cooling capacity of ceiling mounted hydronic radiant panels. The standard applies to free-hanging (suspended) panels with an air gap (not embedded), intended for dry cooling only, fed with water below 120 °C, and having widths between 0.3 m and 1.5 m. It also defines the additional manufacturer data required to ensure correct product application in buildings.

Keywords: ISO 18566-2:2017, ceiling mounted radiant panels, hydronic radiant heating and cooling, heating and cooling capacity, test methods.

Key topics and technical requirements

• Scope and definitions: Covers ceiling-mounted, non‑embedded radiant panels with an air gap; terms and symbols follow ISO 18566-1.
• Test booth requirements: A sealed chamber with six chillable surrounding surfaces, matt paint emissivity ≥ 0.9, limited surface heat flow (< 0.40 W/m²) and controlled internal surface temperatures.
• Reference and measurement points:
  • Reference room temperature measured by a globe thermometer at 0.75 m above floor (150 mm blackened sphere, emissivity 0.9).
  • Air temperature sensors arranged on two vertical axes at three heights.
• Test conditions:
  • Heating and cooling cases defined separately (cooling uses electrical cooling load simulators on the floor).
  • Reference steady-state temperature for cooling tests: 32 °C ± 0.5 K for at least 30 minutes.
  • Surface temperature asymmetry and inlet/outlet temperature differences constrained (e.g., ≤ 0.5 K in certain checks).
• Measurement and calculations:
  • Thermal output Φ calculated from measured water mass/flow and enthalpy differences (reference water pressure 120 kPa).
  • Mass flow measured by calibrated flowmeter or gravimetric method.
• Verification, repeatability and reproducibility:
  • Laboratories must demonstrate repeatability (example tolerance: five consecutive tests within ±20 W) and reproducibility using master panels.

Practical applications and users

• Manufacturers: To generate standardized performance data and product sheets for radiant ceiling panels.
• Test laboratories and certification bodies: For accredited laboratory testing, verification and reporting of panel thermal output.
• HVAC designers and building engineers: To size systems, compare products, and verify that installed panels meet design expectations.
• Specifiers and installers: To ensure correct selection, installation and commissioning per manufacturer data informed by ISO 18566-2 test results.

Keywords: radiant panel testing, HVAC design, product certification, thermal output measurement.

Related standards

• ISO 18566-1 (definitions, symbols, technical specifications)
• ISO 18566-3 (design considerations for ceiling mounted panels)
• ISO 18566-4 (control of ceiling mounted radiant panels)
• ISO 11855 (embedded radiant systems - separate scope)
• References to EN 14240, EN 14037 and ANSI/ASHRAE Standard 138 are noted as foundational sources.