Karnot iSTOR P89 High-Temp Thermal Battery
High-temperature thermal storage for industrial processes and commercial heating
The Karnot iSTOR P89 delivers industrial-grade high-temperature thermal storage using advanced Plentigrade P89 Phase Change Material. With charging temperatures up to 120°C and a discharge temperature of 83.5°C, it is purpose-built for demanding process heat, district heating, and high-temperature commercial applications where conventional thermal stores fall short.
Key Features & Advantages
Engineered for high-temperature industrial applications — the iSTOR P89 delivers powerful thermal storage with exceptional heat output in a compact, robust package.
Industrial-Grade Heat
Charges up to 120°C and discharges at 83.5°C, delivering the high-temperature output required for industrial processes and demanding commercial heating applications.
Dense Energy Storage
Packs 67 kWh of thermal storage into a compact footprint using advanced Plentigrade P89 Phase Change Material for maximum energy density.
Versatile Dual Circuits
Features two independent hydronic circuits (High Power and Low Power) that can be configured to suit any application and load requirement.
Robust & Reliable
Built to withstand demanding environments with a maximum working pressure of 16 bar, ensuring long-term reliability in industrial settings.
Technical Specifications
Comprehensive specifications for system design and installation planning.
Performance & Capacity
| Nominal Storage Capacity | 67 kWh228 kBTU |
| Standby Stored Energy Loss Rate | 5.83 kWh / 24h19.9 kBTU / 24h |
| Design Discharge Outlet Temperature | 83.5°C182.3°F |
| Charging Source Temperature | 95°C to 120°C203°F to 248°F |
Operational & Physical
| Max Flow Rate (High Power Circuit) | 50 L/min13.2 gal/min |
| Max Flow Rate (Low Power Circuit) | 40 L/min10.6 gal/min |
| Maximum Working Pressure | 1.6 MPa (16 bar) |
| Dimensions (W × D × H) | 1200 × 1000 × 1470 mm47″ × 39″ × 58″ |
| Weight | 1,553 kg3,424 lbs |
Additional Advantages
Beyond core performance, the iSTOR P89 delivers system-wide benefits that transform how you manage high-temperature thermal energy.
System Benefits
- Charges from multiple energy and heat sources
- Decouples heat sources from heating demands
- Offers demand side management and shifts heating loads to cheaper off-peak tariffs
- Modular and scalable — thermal batteries can be connected in series or in parallel to increase heat storage capacity
Lower Costs
A Karnot iSTOR P89 thermal battery is clean and fast to install. There's no need to increase the size of expansion vessels nor the volume of water treatment chemicals. Running costs are also low because mandatory annual maintenance and inspections are not required.
Note: As an innovative company committed to continuous improvement, our products are subject to change without prior notice. Always refer to the latest version of this document.
Ready to Optimise Your High-Temperature Thermal Storage?
Contact our technical team for system design assistance and detailed project specifications.
Contact SalesFrequently Asked Questions
Quick answers to the questions most commonly raised by engineers evaluating the high-temperature iSTOR P89 PCM thermal battery for industrial process heat and high-temperature hot water applications.
What is the Karnot iSTOR P89?
The iSTOR P89 is a high-temperature phase change material (PCM) thermal battery with 67 kWh nominal storage capacity. It stores industrial-grade heat: charged at 95–120°C and discharging at 83.5°C through two independent hydronic circuits. Footprint is 1200×1000×1470 mm and weight is 1,553 kg.
How is the iSTOR P89 different from the iSTOR P58?
Same physical footprint and dual-circuit architecture, but the P89 uses a higher-temperature PCM. The P58 charges at 65–80°C and discharges at 54°C — suited to domestic hot water and low-temperature space heating. The P89 charges at 95–120°C and discharges at 83.5°C — suited to industrial process heat, sterilisation, CIP cleaning, commercial laundries, and dairy processing.
Which Karnot heat pump can charge the iSTOR P89?
The P89's 95–120°C charging window matches transcritical CO2 heat pumps (iCOOL / iHEAT CO2) which routinely deliver hot water above 90°C. R290 propane systems max out around 75°C and are not suited to charging the P89.
Why use a PCM thermal battery instead of a lithium battery for industrial heat?
For industrial sites whose load is process heat or hot water (food processing, dairy, hospital sterilisation, commercial laundry), storing energy as heat directly is typically 5–10× cheaper per kWh than storing it as lithium electricity and then converting it back. There are no rare earths, no fire risk, no chemistry that degrades, and no thermal runaway concerns.
Is the iSTOR P89 suitable for tropical Philippine plant rooms?
Yes. The PCM medium is non-flammable, unaffected by high ambient temperatures, and the system is rated to 1.6 MPa (16 bar) working pressure. The standby loss of 5.83 kWh per 24 hours is well-controlled even at Philippine ambient. The P89 is suited to commercial and industrial plant rooms across Luzon and Visayas.
Can multiple iSTOR P89 units be connected together?
Yes. The iSTOR P89 is modular and scalable. Multiple units can be connected in series or in parallel to increase total heat storage capacity. The system can be sized to the customer load profile and expanded later as demand grows, without replacing existing equipment.
What maintenance does the iSTOR P89 require?
The iSTOR P89 has no mandatory annual maintenance or inspection requirement. There is no expansion vessel sizing to increase, no water treatment chemistry to manage, and no pressurised gas charge to monitor. Running costs are minimal compared to traditional pressurised hot water vessels.