TLDR

• Fraunhofer tested industrial heat pumps that produce steam and hot water up to 160°C using the natural refrigerant R-600 (n-butane).
• These systems need custom-designed components, smart controls, and strict safety measures due to the flammable refrigerant and industrial operating conditions.
• The technology offers a cleaner alternative to fossil-fuel boilers, especially for industries with steady heat demand and access to low-carbon electricity.

Fraunhofer ISE has successfully tested industrial heat pumps that produce steam and pressurized hot water at temperatures up to 160°C (320°F). These systems use n-butane, also known as R-600, a natural refrigerant that is flammable and requires special safety measures. Unlike standard HVAC equipment, these heat pumps need custom-designed compressors, hydraulic setups, and smart controls to handle changing industrial demands. The tests show this technology can replace some fossil-fuel boilers in factories and district heating, but installations must be carefully planned to meet safety and performance standards.

Safety and code checklist for R‑600 projects

R-600, also called n-butane, is a natural refrigerant but it is flammable. Designs using R-600 must carefully control the amount of refrigerant, called the charge limit, to reduce fire risk. Proper ventilation is essential to clear any leaks quickly. Leak detection systems should be installed to spot refrigerant escapes early. It’s also important to eliminate ignition sources, such as sparks or open flames, near the equipment.



Where required, hazardous-area rules apply. These are safety standards that prevent fires by controlling electrical and mechanical equipment in places where flammable gases may be present. Projects must also meet local codes for pressure equipment and boilers. These codes cover safe operation under high temperatures and pressures.



Early communication with local code officials, known as the authority having jurisdiction (AHJ), is key. Bringing them into the process helps with hazard analysis and ensures proper training plans are in place. This cooperation smooths approval and keeps installations safe and compliant.

Where high‑temp heat pumps win first

High-temperature heat pumps fit best in industries like food, paper, and textiles. These sectors often need process heat between 100°C and 160°C (212°F to 320°F) and run their systems for many hours each year. District-heating networks also benefit from this temperature range. Ideal sites have strong electric capacity or access to low-carbon power sources. Utilities that offer demand response programs pay users to shift electricity use, improving project economics. Regions with strict rules on boilers, carbon pricing, or incentives for fuel switching make these heat pumps more cost-effective. These factors combine to create the first real markets where high-temp heat pumps can replace fossil-fuel boilers, cutting emissions while meeting industrial heat needs reliably.

How these units reach 160°C—and design impacts

Fraunhofer’s heat pumps achieve temperatures up to 160°C by using specially designed compressors, heat exchangers, and control systems. These components are built to handle the changing demands of industrial processes, not just steady residential heating loads. Proper hydraulic integration is also crucial. This means setting up pressurized-water loops to safely circulate hot water, steam separators to remove excess moisture, and condensate return systems to recycle water back into the process. Separate tests showed that an n-butane (R-600) system can deliver up to 120°C at 125 kW, working in both wet-steam and dry-steam modes. These steam modes refer to how much moisture is in the steam—wet steam contains water droplets, while dry steam is mostly vapor. Together, these design features ensure the heat pumps can reliably replace some industrial boilers while maintaining safety and efficiency.

Action plan for contractors and facility teams

Start by building skills in high-temperature equipment. This includes learning how to handle advanced controls, hydraulic design, commissioning (which means testing and tuning), and safety measures specific to R-600, the flammable refrigerant used in these systems. Next, run a thorough site audit. Check the temperature lift, which is the difference between the heat source and the heat output. Understand the load profile—how heat demand changes throughout the day or season—and confirm the available electric capacity to support the system. Finally, pilot the heat pump on one production line or heating loop first. Track key performance indicators like COP, which stands for coefficient of performance and measures efficiency, uptime, and maintenance needs. Use this real-world data to adjust and scale the system safely and effectively over time.

Key Takeaways

• Fraunhofer’s industrial heat pumps can produce process steam and pressurized hot water up to 160°C (320°F), offering a clean alternative to fossil-fuel boilers in factories and district heating systems.
• These high-temperature heat pumps use n-butane (R-600), a natural but flammable refrigerant, requiring strict safety measures like ventilation, leak detection, and adherence to local codes.
• Successful installation demands custom-designed components, hydraulic integration, and smart controls tailored to changing industrial loads—this is not a simple upgrade of residential heat pumps.
• Contractors and facility managers should develop expertise in high-temp equipment, hydraulic design, controls, and flammable refrigerant safety, starting with site audits and pilot projects to optimize performance and reliability.

Frequently Asked Questions

What makes Fraunhofer's industrial heat pumps different from conventional HVAC equipment?

Fraunhofer’s heat pumps produce high-temperature steam up to 160°C (320°F), which is much hotter than typical HVAC systems. They require custom-designed compressors, heat exchangers, and controls tailored to industrial needs, not just simple upgrades of existing equipment.

Why is the refrigerant R-600 (n-butane) used, and what safety measures are needed?

R-600 is a natural refrigerant with low environmental impact but is flammable. Systems using it must follow strict safety rules like charge limits, ventilation, leak detection, and ignition prevention. Early coordination with local code officials is essential to meet all safety and legal standards.

Which industries or applications benefit most from these high-temperature heat pumps?

Industries like food processing, paper production, textiles, and district heating systems that need steam or hot water between 100°C and 160°C benefit most. Sites with good electric capacity and regions with carbon reduction goals find these heat pumps especially valuable.

What should contractors and facility managers consider before installing these heat pumps?

Contractors need skills in high-temperature equipment, hydraulic design, controls, commissioning, and flammable refrigerant safety. Facility managers should audit site conditions like temperature needs, load profiles, and electric capacity. Starting with a pilot project helps track efficiency and service needs before scaling up.

Related Topics: Fraunhofer heat pumps, 160°C process steam, high-temp heat pumps, boiler replacement, R-600 safety, HVAC heat pumps, custom hydraulics, smart HVAC controls, industrial heat pumps, energy efficient heating, process steam technology, HVAC safety standards