Radiant heat vs contact heat – what is the difference for product selection?

Short answer: Radiant heat transfers through infrared radiation without touching the hot surface. Contact heat transfers through direct conduction when the sleeve/tube touches the hot component. The required construction depends on exposure type, clearance, airflow, and temperature.

Radiant heat (no direct contact)

• Common near turbo housings, exhaust manifolds, downpipes, and hot pipes
• Improves significantly when you reduce heat at the source using exhaust insulation solutions
• Best practice: maintain clearance where possible, and protect hoses with fire sleeve or suitable thermal sleeving

Contact heat (touching hot parts)

• Occurs when routing is tight and the hose/sleeve contacts hot metal
• Requires more conservative selection and mechanical protection at rubbing points
• May require combined protection: source insulation + sleeve + fastening/routing improvements

Practical selection tip: If there is any chance of contact under vibration, treat it as contact heat (more severe) and add abrasion control where the sleeve may rub against brackets or clamps.

Send your routing photos for selection confirmation