ISO 15042:2017

Overview

ISO 15042:2017 - Multiple split-system air conditioners and air-to-air heat pumps - provides standardized procedures for testing and rating capacity and efficiency of air-cooled multi‑split systems. The standard covers basic, modular and modular heat‑recovery multi‑split systems (multi‑split air conditioners and multi‑split heat pumps) with non‑ducted and/or ducted indoor units, including indoor units supplied without fans. It specifies standard test conditions, methods and reporting so manufacturers, test laboratories and regulators can produce comparable performance data for product rating and certification.

Key topics and technical requirements

• Scope and applicability

  • Applies to residential, commercial and industrial split‑system air conditioners and air‑to‑air heat pumps that are factory‑made, electrically driven and mechanically compressed.
  • Covers single- and multiple‑circuit systems with limited control steps, and variable‑speed compressor systems with three or more capacity steps.
  • Testing and rating are based on matched assemblies (combinations of outdoor and multiple indoor units).
  • Exclusions: water‑cooled/source equipment, mobile single‑duct units with condenser exhaust duct, absorption cycle equipment, individual components, and certain ducted/ single-controller systems (see ISO 5151/ISO 13253). Ducted units < 8 kW and < 25 Pa are excluded.

• Test coverage

  • Cooling tests: capacity, maximum/minimum performance, freeze‑up drip, condensate control and enclosure sweat.
  • Heating tests: heating capacity, maximum/minimum heating, defrost operation and automatic defrost performance.
  • Heat recovery tests: heat recovery capacity ratings for systems that transfer recovered heat between indoor units.
  • Airflow settings, outdoor airflow, and indoor unit configurations are specified for repeatable measurements.

• Test methods and accuracy

  • Permitted methods include calorimeter and indoor air enthalpy test methods.
  • Requirements for data collection periods, preconditioning, uncertainties of measurement, test tolerances and result adjustments are provided.
  • The standard does not determine seasonal efficiency or seasonal part‑load performance.

Practical applications - who uses ISO 15042:2017

• Manufacturers: product development, performance declarations and compliance testing.
• Independent test laboratories: standardized test procedures and reporting for certification.
• Regulators and energy labeling programs: baseline performance data for regulations and labels.
• HVAC specifiers, consultants and procurement teams: comparing multi‑split system capacities, efficiencies and heat‑recovery capabilities.
• Certification bodies: evaluating matched assemblies for safety and efficiency claims.

Related standards

• ISO 5151 - testing/rating of ducted air conditioners and heat pumps (referenced for certain single‑controller systems).
• ISO 13253 - testing of multiple split‑systems controlled by a single thermostat/controller.

Keywords: ISO 15042:2017, multiple split-system, multi-split air conditioners, air-to-air heat pumps, testing and rating, cooling capacity, heating capacity, heat recovery, calorimeter test, indoor air enthalpy.