Technical guidance released for R290 refrigerant defrost heater temperature limits

Shengzhou Jinwei Electric Heating Appliance has released guidance regarding surface temperature limits for defrost heaters in refrigeration units utilizing R290 (propane) refrigerant. The company identifies a maximum surface temperature threshold of 370 °C, derived from the 470 °C auto-ignition temperature of propane minus a mandatory 100 K margin required by European system safety standards.

The company emphasizes that no unique "R290-certified" heater standard exists. Instead, compliance is governed by broader safety frameworks, including EN 378-2 and the EN IEC 60335-2 series. Designers are responsible for ensuring that defrost heater sheaths do not exceed these limits in scenarios where leaked refrigerant might come into contact with the component.

Shengzhou Jinwei notes that while a heater operating at 200 °C or 300 °C is not inherently non-compliant, system safety depends on structural geometry and refrigerant charge volume. The company urges engineers to prioritize documented sheath temperatures under stated operating conditions over generic catalogue specifications to ensure adherence to safety regulations regarding flammable refrigerants.