High-Voltage PTC Heaters for Electric Bus Rooftop HVAC

As electric buses and commercial EVs evolve, efficient thermal management becomes essential to ensure passenger comfort, extend battery life, and protect driving range.

In winter, cabin heating is one of the largest energy consumers because there is no engine waste heat. Every kilowatt of heating comes directly from the traction battery.

• Slow warm-up and uneven temperature inside the cabin during cold starts.
• Range reduction when traditional electric heaters draw high continuous power.
• High-voltage safety, inrush current, and reliability concerns for rooftop-mounted systems.

KLC’s high-voltage PTC rooftop HVAC heaters are engineered to solve these challenges and support next-generation electric bus platforms.

KLC Corporation specializes in PTC heaters and high-voltage PTC heaters for electric vehicles, with solutions from 12V up to 999V and UL/CSA approvals for 12V–600V systems.

For electric bus rooftop HVAC, our high-voltage PTC heaters deliver fast heating, self-regulating temperature control, high safety, and long service life.

• Wide voltage range suitable for 400–800 VDC electric bus systems.
• Modular power configuration to meet 3–20 kW class rooftop HVAC requirements.
• IP-rated and automotive-grade designs for harsh rooftop environments.

Learn more about our high-voltage portfolio on the High Voltage PTC Heaters category page.

By integrating KLC high-voltage PTC heaters into rooftop HVAC units, bus OEMs and HVAC integrators can achieve both comfort and efficiency.

• Fast and uniform cabin warm-up – High power density and optimized fin design support rapid air heating and comfort across the passenger area.
• Self-regulating and energy-efficient – PTC ceramics automatically adjust power as temperature rises, avoiding overheating and reducing unnecessary energy consumption.
• High-voltage safety and reliability – Designed for 350–800 VDC bus systems with self-limiting temperature and optional safety fuses for extra protection.
• Modular design for different bus sizes – Multiple PTC modules can be combined inside a single rooftop HVAC module to suit city buses, intercity buses, or coaches.
• Automotive-grade quality – IATF 16949, ISO 9001, and UL/CSA approvals help meet global EV standards and customer requirements.

KLC high-voltage PTC heaters are used in many electric vehicle heating scenarios:

• Electric bus rooftop HVAC – primary cabin heating for passengers and driver.
• Defrost and demist – integrated air heaters for windshield and side-window defogging.
• Cabin and battery combined systems – air-side heating plus coolant-based battery thermal management.
• Electric trucks and special EVs – HVAC heating for cabins and equipment compartments.

For a complete overview of EV heating solutions, visit PTC Heaters for Electric Vehicles: Your Complete Guide.

Each electric bus project is different, but many share similar technical requirements. KLC supports engineers with design, simulation, and validation.

Electrical and Thermal Design

• High-voltage DC input: typically 400–800 VDC (up to 999 V for certain STW-type models).
• Power range: from hundreds of watts per module up to several kilowatts per rooftop HVAC system.
• Optimized fin pitch and airflow channels for low pressure drop and efficient heat transfer.

Mechanical and Environmental Performance

• Strong endurance against vibration, humidity, and dust on bus rooftops.
• Customizable dimensions to match rooftop HVAC housings and duct layouts.
• Optional IP-rated designs for outdoor or harsh environments.

Safety, Control, and Testing

• Self-regulating PTC elements with optional built-in thermal fuses.
• Compatible with staged power control, PWM, or other vehicle HVAC control strategies.
• Validated by airflow & heat analysis, lifecycle testing, vibration, and humidity tests.

For detailed model data, please refer to our PTC Air Heaters – High Voltage STW Type and other PTC Air Heaters.

KLC engineering supports customers from early concept to SOP, helping to match PTC heater performance with real duty cycles and climate conditions.

• Thermal design support: 3D modeling, CFD simulations, and prototype evaluation.
• Custom interfaces: mounting frames, wiring, connectors, and safety components.
• Documentation and samples: 3D STEP files, datasheets, and test reports for design validation.

If you need to combine rooftop HVAC heating with battery or coolant heaters, see also our PTC Heaters for Constant Battery Discharge.

Whether you are designing a new electric bus platform or upgrading an existing HVAC system, KLC high-voltage PTC heaters can help you achieve reliable, safe, and energy-efficient heating.

Contact our team today for technical consultation, 3D simulation support, or sample requests for your EV and electric bus projects.

Contact KLC EV Heating Team