1. Overview

Air-to-water heat pump systems are widely used in residential, renovation, and light commercial HVAC applications as a low-carbon alternative to traditional boiler systems.

In European and international retrofit markets, heat pump selection is typically based on system efficiency, heating performance at different ambient conditions, leaving water temperature capability, installation flexibility, and compatibility with existing heating distribution systems.

This document compares two 12–15 kW class R290 air-to-water heat pump systems:

EXINDA 12kW R290 Heat Pump 
Bosch Compress 8800i AW 

Both systems are designed for residential heating and domestic hot water applications and are commonly used in retrofit and new-build HVAC projects across cold and moderate climate regions.

2. System Working Principle

Both EXINDA and Bosch heat pump operate on the same air-to-water thermodynamic principle:

• Heat extraction from outdoor air via refrigerant cycle

• Compression to increase thermal energy

• Heat transfer to hydronic water circuit

• Distribution to radiators, underfloor heating, or buffer tanks

System performance in real applications is influenced by:

• Outdoor ambient temperature

• Heating system water temperature requirements

• Hydraulic system design

• Defrost strategy under low ambient conditions

Both systems are designed for hydronic heating compatibility in residential HVAC infrastructure.

3. Heating Capacity & Operating Range 

In residential heat pump applications, system performance is typically evaluated under EN14511 test conditions such as A7/W35 and A-7/W55.

EXINDA 12kW Heat Pump

• Nominal heating capacity: 12 kW

• Variable performance depending on ambient conditions

• Heating output at standard conditions ranges approximately around 5–12 kW depending on water temperature and load conditions

• DC inverter compressor with continuous modulation control

Bosch Compress 8800i AW

• Heating capacity range: 10.7 kW – 14.6 kW (model dependent)

• Modulation range: approximately 4.0 – 12.5 kW (A-2/W35 condition)

• Multi-model platform (11 / 13 / 15 kW series)

Summary

Both systems are suitable for residential heating loads.
Bosch provides a multi-capacity platform, while EXINDA operates as a single 12 kW inverter-based system designed for continuous modulation.

4. Seasonal Efficiency

Heat pump efficiency varies depending on seasonal conditions and heating system temperature levels.

EXINDA

• COP range: approximately 4.0 – 5.08 under EN14511 conditions

• Higher efficiency observed under mild ambient conditions depending on load variation

Bosch

• SCOP (35°C): up to 5.0 – 5.4 depending on model

• SCOP (55°C): approximately 4.0 – 4.13

• Energy efficiency class: A+++ (at 35°C and 55°C)

Summary

Both systems meet high-efficiency European standards.
Bosch provides clearly defined SCOP performance across multiple configurations, while EXINDA delivers competitive efficiency within its operating envelope.

5. Low Ambient Temperature Performance

Heat pump operation in cold climates is determined by compressor control strategy, defrost logic, and refrigerant system stability.

EXINDA

• Operating ambient range: -25°C to 43°C

• Designed for stable heating operation in extreme low-temperature environments

• Intelligent defrost and anti-freeze protection system

Bosch

• Designed for cold climate operation (exact limit depends on system configuration)

• Optimized for European winter retrofit conditions

• Stable operation under low ambient conditions with R290 refrigerant system

Summary

Both systems are designed for winter operation.
EXINDA is engineered for extended operation down to -25°C ambient temperature, making it suitable for colder climate regions and high-latitude applications.

6. Leaving Water Temperature 

Leaving water temperature is a key parameter in retrofit applications, especially when existing radiators are retained.

EXINDA

• Heating water outlet temperature: 35°C – 60°C

Bosch

• Maximum leaving water temperature: up to 75°C

Summary

Bosch provides higher maximum water temperature capability, which supports direct replacement of boiler-based radiator systems.
EXINDA is optimized for low-to-medium temperature hydronic systems including underfloor heating and modern radiator configurations.

7. Refrigerant Technology & Environmental Impact

Both systems use next-generation natural refrigerant technology.

EXINDA

• Refrigerant: R290 (Propane)

• GWP: 3

• Refrigerant charge: 0.8 kg

Bosch

• Refrigerant: R290 (Propane)

• GWP: approximately 0.02 

Summary

Both systems use R290 natural refrigerant, supporting low-carbon heating strategies and compliance with future environmental regulations.

8. Noise Performance

Noise level is influenced by compressor load, fan speed, and installation environment.

EXINDA

• Sound pressure: 61 / 57 / 38 dB(A) (day / rated / low mode)

Bosch

• Sound level range: approximately 45–65 dB(A) depending on operating mode and model

Summary

Both systems are designed for residential outdoor installation.
Actual noise performance depends strongly on installation conditions and load operation.

9. Installation & System Integration

EXINDA

• Compact outdoor unit design

• Standard hydronic connection (G1”)

• Suitable for flexible residential installation layouts

Bosch

• Plug & Play installation system with puffertower concept

• Strong retrofit-oriented installation design

• Integrated digital service ecosystem

Summary

Bosch focuses on system integration and retrofit installation efficiency.
EXINDA focuses on installation flexibility and system adaptability across project types.

10. Control System & Engineering Application

EXINDA

• DC inverter control system

• Intelligent defrost and anti-freeze protection

• Cascade operation capability (multi-unit systems)

Bosch

• Integrated WiFi gateway (K 40 RF)

• Remote monitoring via HomeCom Pro platform

• Digital service and maintenance ecosystem

Summary

Bosch provides a more integrated digital service platform.
EXINDA emphasizes scalable system engineering for multi-unit HVAC applications.

11. Engineering Summary

From an engineering perspective, both EXINDA and Bosch heat pump systems are suitable for residential and retrofit hydronic heating applications.

EXINDA 12kW Heat Pump

• Stable operation down to -25°C ambient temperature

• R290 natural refrigerant system

• Continuous inverter modulation

• Suitable for cold climate and variable load conditions

Bosch Compress 8800i AW

• High leaving water temperature capability up to 75°C

• Multi-capacity platform (11–15 kW range)

• Strong retrofit compatibility with existing radiator systems

• Integrated digital service ecosystem

The optimal selection depends on:

• Climate conditions

• Heating system type (radiator / underfloor heating)

• Required leaving water temperature

• Retrofit vs new build application

• System integration and service ecosystem requirements

12. FAQ

Q1: Are both heat pumps suitable for residential heating?

Yes. Both systems are designed for residential and light commercial hydronic heating applications.

Q2: What is the main technical difference?

The main differences are low ambient operating capability, leaving water temperature, and system integration approach.

Q3: Which system performs better in cold climates?

EXINDA is designed for stable operation down to -25°C ambient temperature, making it suitable for harsher winter regions.

Q4: Are both systems using R290 refrigerant?

Yes. Both systems use R290 natural refrigerant with low environmental impact.

Engineering Contact

EXINDA HVAC Systems
Email: info@exindagroup.com